Core Topics in General and Emergency Surgery

Colonic emergencies

David E. Beck

Introduction

Emergency conditions of the large bowel are common and changes in their evaluation and management have continued. Rather than rushing the patient to the operating room after a token resuscitation, current standards suggest that an initial appropriate period of resuscitation along with physiological and radiological evaluation should be undertaken. Many patients with colonic conditions can be managed non-operatively with bowel rest, antibiotics and blood components. Comorbid disease such as cardiac, pulmonary and metabolic conditions are optimised and critically ill patients are monitored in an intensive care setting. If adequate facilities and personnel are not readily available, transfer to a tertiary care facility should be considered if the patient can be readily stabilised.

The operative mortality for emergency colon resections is two to three times that associated with elective resection. As a result, surgeons have investigated ways of stabilising patients in order to convert emergency into more planned, elective procedures. Deciding if and when to operate can be difficult, and active observation and consultation with colleagues is often helpful in the decision-making process. Active participation of the attending/consultant surgeon in both the assessment and operative procedure is essential in this group of very challenging patients.

When emergency surgery is necessary, there has been a clear trend towards single rather than staged procedures for large-bowel disorders. When feasible, this approach reduces the length of hospital stay and avoids the risks of multiple operations. However, in some unfit or acutely septic patients, a staged approach may still be preferable.

Preparation For Operation

Patients should be adequately informed of their likely diagnosis and management options. Alternatives and risks as well as the potential need for a stoma should be explained carefully. Patients requiring emergency large-bowel surgery should be marked for potential stoma sites and if possible participation of a stoma therapist arranged.

The risk of postoperative deep vein thrombosis and pulmonary embolus is substantial in this group of patients, and prophylactic measures are essential. Options include intermittent pneumatic calf compression and subcutaneous low-molecular-weight heparin. Prophylactic antibiotic therapy is standard, with broad-spectrum single-dose therapy as effective as multiple-dose regimens. The duration of prophylactic antibiotics should be less than 24 hours. If significant infection or contamination is found intraoperatively, empirical therapeutic antibiotics may be indicated.

Disease Process

Colonic emergencies can be divided into ischaemia, obstruction, perforation and bleeding. These categories will be discussed in turn, with attention to their pathophysiology, evaluation and management.

Colonic ischaemia

Although the colon has a generous overlapping blood supply, any interruption in blood flow produces ischaemia. Anatomical locations that have the potential to be vulnerable to ischaemic disease include: Griffith's point at the splenic flexure (junction of the superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA)); Sudeck's critical point at the mid-sigmoid colon (junction of the IMA and hypogastric vasculature); and the caecum (distal distribution of the SMA).

Aetiological Factors And Pathophysiology

As outlined in Box 10.1, colonic ischaemia can result from a number of conditions.

 

Box 10.1   Classification of ischaemic colitis

I Interruption of flow in large vessels

A Following ligation during aortic surgery

B Injury secondary to angiographic, blunt or penetrating trauma

C Spontaneous thrombosis of large vessels

II Intrinsic small-vessel disease

III Low-flow state in the critically ill

IV Spontaneous ischaemic colitis without demonstrable vessel occlusion

A Self-limiting without sequelae

B With subsequent stricture formation

V Miscellaneous

A Secondary to luminal obstruction

B Young adults

C Renal allograft recipients

Interruption of flow in large vessels following aortic surgery varies from 1–2% for elective cases to as high as 60% during emergency aneurysm repair.1 Sudden occlusion of the IMA can also occur as a result of angiographic trauma with subintimal dissection or as a result of either blunt or penetrating abdominal trauma. Atheromatous narrowing or occlusion of the IMA is not unusual. However, in most cases this occurs gradually, and the collateral circulation from the SMA can compensate for the decrease in flow through collateral circulation via the marginal artery. If the IMA becomes acutely thrombosed or occluded with an embolus and the collateral circulation is inadequate, the clinical picture will be similar to that found after IMA ligation during aortic surgery.

Any of the connective tissue diseases that produce inflammation in the small-intestinal arteries (intrinsic small-vessel disease) can also result in colonic ischaemia.2 Another variant of ischaemic colitis occurs in patients who are severely ill with conditions that cause hypotension, decreased cardiac output or peripheral vasoconstriction, with a decreased flow to the end organ (low-flow states). This group of patients appears to have a higher incidence of full-thickness necrosis and right-sided involvement than do those with spontaneous ischaemic colitis who were previously well. The mortality associated with colonic infarction in these patients who are severely ill from another disease process is extremely high. In one report of 17 such patients the mortality rate was 57%.3 One must therefore have a very high index of suspicion for full-thickness necrosis in this group of patients and be ready to intervene early.

Spontaneous ischaemic colitis may occur without any demonstrable vessel occlusion on angiography.4 The pathological changes seen in the colon are identical to those caused by vessel occlusion and resulting decreased in blood flow to the colon. The spectrum of disease varies from mild submucosal oedema to frank full-thickness necrosis. Most cases are the milder self-limiting variety that are typically seen in middle-aged or elderly patients, often following episodes of dehydration. In younger patients, who are mostly women, there has been an association between ischaemic colitis and the use of oral contraceptive drugs.5

Diagnosis

Colonic ischaemia usually presents in one of two ways. The milder cases are manifest by diffuse and/or bloody diarrhoea. Patients with frank colonic infarction frequently develop acidosis, glucose intolerance, renal failure, obvious sepsis, and abdominal distension or tenderness. The diagnosis of postoperative ischaemia can be made with flexible sigmoidoscopy performed at the bedside. If the symptoms are not explained by flexible sigmoidoscopy, a colonoscopy may occasionally be required to rule out more proximal disease. The endoscopic appearance of colonic ischaemia may range from submucosal oedema with haemorrhage and ulceration to the dusky blue mucosal colour of infarction. Frank gangrene mandates immediate surgery and resection; however, the colon with just mucosal oedema and haemorrhage may be watched closely.

The diagnosis can be made with endoscopy, barium enema or computed tomography (CT). Endoscopy can be performed in the office or at the bedside and the pathological state can be viewed directly (Fig. 10.1). CT is rapidly becoming more common and ischaemia presents as thickened bowel wall (Fig. 10.2).

FIGURE 10.1 Endoscopic view of colonic ischaemia.

FIGURE 10.2 CT scan of colonic ischaemia.

There are three possible outcomes of ischaemic colitis:

  1. Resolution of the process is the most common clinical course.
  2. Progression to full-thickness necrosis is unusual, especially if there is no evidence of gangrenous bowel at the first examination.
  3. The condition may evolve to an ulcerative stage, which may eventually result in stricture formation. During the ulcerative stage the endoscopic and radiographic findings may mimic Crohn's disease. Occasionally the early phases of this disease will go unnoticed or undiagnosed, and the patient will present with a stricture.

Ischaemic colitis may also be associated with a complete or partial bowel obstruction. In one reported series,6 10% of patients with colonic ischaemia had an associated carcinoma and another 10% had some other condition that potentially interfered with colonic motility. When ischaemic colitis occurs in association with tumour, the ischaemic area is usually proximal to the tumour and may or may not be associated with obstruction. The investigators in this study and others speculated that colonic blood flow could be decreased as a consequence of increased intraluminal pressure, hyperperistalsis with increased muscular spasm, and resultant diminution of blood flow in the colonic wall, or a decrease in aortic blood pressure and vena caval return with straining in obstructive lesions.7 Knowledge of this association is of obvious importance to avoid using ischaemic bowel for an anastomosis.

Treatment

If the diagnosis of ischaemic colitis is made early, non-operative treatment is warranted in the first instance. Mild cases can be managed on an outpatient basis with a clear liquid diet, close observation and possibly antibiotic therapy. More serious cases require hospitalisation, bowel rest, nasogastric suction (if there are any signs of ileus), and optimisation of blood flow to the mucosa (intravenous hydration and optimisation of cardiac output). If the patient is receiving digitalis, a serum level should be checked because toxic digitalis levels can have a marked vasoconstrictive effect on visceral circulation. Parenteral antibiotics (such as a second- or third-generation cephalosporin) are used by some surgeons because of the suggestion that colonic ischaemia may allow colonic bacterial transmigration, although there are no strong data to support or refute their use. Patients with ischaemia resulting from arteritides may respond to corticosteroid treatment.

Specific indications for surgery include peritonitis, perforation, sepsis and failure of non-operative therapy. At operation a wide resection of non-viable colon is performed. Primary anastomosis is usually unsafe because of the potential for postoperative progression of the ischaemia. A double-barrel stoma or end stoma and separate mucous fistula is safer and allows assessment of the bowel viability in the postoperative period. The mortality rate for ischaemic colitis among renal transplant patients is 70%.2 Diagnostic manoeuvres should therefore be initiated at the first suspicion of ischaemia in these high-risk patients, and surgery should be aggressive once the diagnosis is made (resection of any compromised bowel with an end stoma). Primary anastomosis after resection is ill advised in these patients.

Colonic obstruction

Colonic Volvulus

Volvulus can be defined as a twisting or torsion of bowel around its mesentery and occurs most commonly in the sigmoid colon (76%), but also in the caecum (22%) and the transverse colon (2%).8 One report suggested that 40–60% of patients have had previous episodes of obstruction.9 In the USA, volvulus represents a rare cause of intestinal obstruction, encompassing less than 5% of large-bowel obstructions. However, worldwide it may represent more than 50% of the cases in some countries.10

Sigmoid volvulus

The sigmoid colon rotates through 180–720° in either a clockwise or anticlockwise direction to produce the volvulus.11 A narrowed sigmoid mesocolon provides a pedicle for rotation. The condition is occasionally associated with Chagas' disease and Hirschsprung's disease, in which redundancy of the colon is a feature, in addition to non-specific motility disorders of the colon.12

A typical patient with a sigmoid volvulus presents with abdominal pain, constipation and feeling bloated. On examination there is marked distension, which is often asymmetrical. Severe pain and tenderness, associated with tachycardia and hypotension, may suggest colonic ischaemia. Patients who develop sigmoid volvulus in the industrialised world tend to be older, and one-third either have mental illness or are institutionalised.12

Findings on the plain abdominal radiograph are often characteristic. Massive distension of the sigmoid colon is visible; the bowel loses its haustration and extends in an inverted U from the pelvis to the right upper quadrant of the abdomen (Fig. 10.3). Fluid levels are seen in both limbs of the loop on the erect film, commonly at different levels (‘pair of scales’). In one-third of patients, the appearances are atypical and a water-soluble contrast enema should be carried out. This may demonstrate narrowing of the contrast column at the point of twisting, which has been described as resembling the beak of a bird of prey.

FIGURE 10.3 Radiograph of the abdomen demonstrates the characteristic massive dilation of the sigmoid colon arising from the pelvis and extending to the right diaphragm. The arrow points to three lines representing the twisted walls of the sigmoid colon, which converge in the left lower quadrant.

Volvulus patients often present with significant fluid and electrolyte abnormalities, which require careful correction. Untwisting and decompression are the initial treatments of choice as long as the patient lacks clinical features suggestive of colonic strangulation. Untwisting has been described using several techniques, including rigid or flexible sigmoidoscopy, colonoscopy, blind passage of a rectal tube, and instillation of rectal contrast during a barium enema examination.1315 The endoscopic method of decompression has the advantage that decompression can be done under vision, increasing the accuracy of insertion through the twisted segment in the sigmoid colon. In addition, the mucosa of the whole sigmoid loop can be visualised directly and the identification of gangrenous mucosal patches is an indication for operative management.

If symptoms and signs suggest ischaemia of the colon, laparotomy should be undertaken after the patient has been adequately resuscitated. Likewise, the patient who has unsuccessful non-operative treatment and those who have clinical features suggestive of colonic ischaemia at colonoscopy should also undergo emergency laparotomy. Since it is likely that resection will be required, the patient should be placed in the lithotomy/Trendelenburg position on the operating table. If colonic distension makes it difficult to handle the colon, a needle inserted obliquely through a taenia coli attached to a suction apparatus aids decompression. If the colon is gangrenous, it should be resected with as little manipulation as possible; the most widely recommended procedure is a segmental colectomy with an end colostomy and closure of the rectal stump (Hartmann's operation). In a prospective randomised trial from West Africa, Bagarani et al. compared the operative treatment in 31 patients with or without gangrene.16 When gangrene was present, the mortality for Hartmann's procedure was 12.5% compared with 33.3% when resection and anastomosis were performed.

A small number of surgeons have described resection and primary anastomosis with good results. A study from India reported 197 patients with acute sigmoid volvulus treated by single-stage resection and anastomosis, 23 of whom had gangrene of the bowel.17 Only two patients had anastomotic leaks, both of which responded to non-operative management. The two mortalities occurred in elderly patients who presented with perforations. A study from Ghana reported 21 patients with acute sigmoid volvulus treated by single- stage resection and anastomosis, 15 of whom had gangrene of the bowel.18 Only one patient had a minor anastomotic leak, which responded to conservative management. However, it is important to stress that the majority of the patients in these studies were young and these results may not be applicable to the typical Western patient. In contrast, a series from the USA with 228 patients reported a mortality rate of 24% for emergency operations and 6% for elective operations. This study found mortality to correlate with emergency surgery and necrotic colon.14

Intraoperative colonic irrigation may facilitate primary anastomosis in patients with sigmoid volvulus who require emergency operation, since faecal loading proximal to the volvulus may increase the risk of anastomotic dehiscence. However, it is still important that only patients who are generally fit and without systemic sepsis and peritoneal contamination are selected for this procedure.

Because the risk of recurrent volvulus after decompression and de-rotation has been reported to be between 40% and 60%,9 elective surgery to prevent further volvulus should always be considered. The most widely accepted procedure is resection, which is now associated with an operative mortality of 2–3%. The operation may be performed as a laparoscopic-assisted procedure through a small incision under local anaesthesia if required.

A variety of fixation procedures have been described but have been associated with high recurrence rates.15

Ileosigmoid knotting

Ileosigmoid knotting is a variant of sigmoid volvulus in which the ileum twists around the base of the mesocolon (Fig. 10.4). It is also known as double volvulus. Three factors are responsible for ileosigmoid knotting: (i) a long small-bowel mesentery and freely mobile small bowel; (ii) a long sigmoid colon on a narrow pedicle; and (iii) ingestion of high-bulk diet in the presence of empty small bowel.19

FIGURE 10.4 Ileosigmoid knotting.

The condition is characterised by very acute onset of agonising generalised abdominal pain and repeated vomiting. Gangrene of the ileum and sigmoid colon is common. Generalised peritonitis, sepsis and dehydration are recognised complications, with hypovolaemic shock occurring early. The erect plain abdominal radiograph shows a dilated sigmoid colon and fluid levels in the small bowel.

Initial management consists of resuscitation and administration of antibiotics followed by surgical intervention. Resection and anastomosis of the terminal ileum and a Hartmann procedure is the most commonly performed operation. Recent reports suggest that primary colonic anastomosis can be undertaken safely when there is a short history and the colon is clean and well vascularised. The condition unfortunately carries a very high mortality rate, ranging from 15% to 73%.20

Transverse colon volvulus

Volvulus affecting the transverse colon is less common than sigmoid volvulus, accounting for only 2.6% of all cases of colonic volvulus in one series.21 Predisposing conditions include pregnancy, chronic constipation, distal colonic obstruction and previous gastric surgery. The plain abdominal radiograph usually shows gas-filled loops of large intestine with wide fluid levels. The condition is often mistaken for sigmoid volvulus and the diagnosis is rarely made preoperatively. After the operative diagnosis is confirmed and the transverse colon untwisted, evidence of distal obstruction should be sought. Operative choices include a transverse colectomy or an extended right hemicolectomy.

A primary anastomosis after resection is probably safe. However, in the presence of gangrenous bowel and significant peritoneal contamination, the safest approach may be to resect the affected colon and exteriorise both ends.

Caecal volvulus

Volvulus of the caecum is less common than volvulus of the sigmoid colon, representing 28% of all cases of colonic volvulus reported over a 10-year period in Edinburgh.22 It is likely that incomplete rotation of the midgut leaves the caecum and ascending colon inadequately fixed to the posterior abdominal wall with a substantial length of mesentery. Conditions that alter the normal anatomy may predispose to caecal volvulus. There is an increased risk of caecal volvulus in pregnancy, and some patients are found to have adhesions from previous surgery. There is also an association with distal colonic obstruction. Volvulus usually takes place in a clockwise direction around the ileocolic vessels and, although the term ‘caecal volvulus’ is used, the condition also involves the ascending colon and ileum. As it twists, the caecum comes to occupy a position above and to the left of its original position. A similar condition, which is seen very occasionally, is ‘caecal bascule’. In this condition, the caecum folds upwards on itself, producing a sharp kink in the ascending colon.

It is difficult to differentiate between caecal volvulus and other forms of proximal large-bowel obstruction on clinical grounds. Some patients will have a previous history of episodes of obstruction that subsequently settled with non-operative treatment. The main presenting symptoms are colicky abdominal pain and vomiting. A tympanitic abdominal swelling will usually be present in the mid-abdomen.

On the supine abdominal radiograph, a ‘comma’-shaped caecal shadow in the mid-abdomen or left upper quadrant with a concavity to the right iliac fossa is diagnostic (Fig. 10.5) and there may be small-bowel loops lying to the right side of the caecum. A single, long fluid level on the erect film is characteristic. If doubt persists, a contrast enema will show a beaked appearance in the ascending colon at the site of the volvulus (Fig. 10.6).

FIGURE 10.5 Abdominal radiograph demonstrates a massively dilated caecum folded over into the left upper quadrant with distended small bowel.

FIGURE 10.6 Water-soluble contrast enema demonstrates a beak-like termination at the point of obstruction in the ascending colon with a markedly dilated caecum seen high in the abdomen.

Management depends on the clinical picture. The patient who is unfit for surgical treatment can be considered for colonoscopy since occasional successes have been reported using this method.23 However, laparotomy is necessary in most patients. If the right colon is gangrenous at operation, the treatment of choice is a right hemicolectomy. A primary anastomosis should be possible in most cases even in the presence of contamination of the peritoneal cavity. It should be remembered that there is a markedly increased mortality in patients who have caecal gangrene. A report from the Mayo Clinic found a mortality rate of 12% in patients with caecal volvulus with a viable caecum, rising to 33% in the presence of colonic gangrene.24

There is more controversy about the procedure of choice in patients who have a viable caecum after reduction of the volvulus. On the one hand untwisting alone is associated with a high recurrence rate, but on the other hand resection, which avoids all risk of recurrence, carries a small risk of anastomotic leak. However, in one study of 22 patients there was no mortality and no anastomotic leaks. A 14% morbidity included one abdominal wall abscess, one intra-abdominal abscess and one medical complication.25 The other two procedures commonly performed for caecal volvulus are caecostomy and caecopexy. Reports on the use of caecostomy demonstrate a wide variation in terms of both recurrence (0–25%) and mortality (0–33%). Some authors express concern over the morbidity of caecostomy and the occasional serious complication of abdominal wall sepsis and fasciitis, in addition to the potential for a persistent fistula.

 

The treatment of caecal volvulus has been reviewed in a large study comprising 561 published cases.26 This review showed that caecopexy was associated with a mortality rate of 10% and a recurrence rate of 13%. If all circumstances are favourable, resection appears to be a justifiable procedure with minimal risk of recurrence, accepting that there may be a small number of patients who will have increased bowel frequency. In other circumstances, the minimum procedure compatible with survival becomes the goal.

Acute Colonic Pseudo-Obstruction

Acute colonic pseudo-obstruction (ACPO) is the term used to describe the syndrome in which patients present with symptoms and signs of large-bowel obstruction but in whom no mechanical cause can be demonstrated at contrast radiology. In more than 80% of patients with ACPO, an underlying precipitating condition exists, of which at least 50 have been described.27 The most common of these associated conditions are metabolic disorders, trauma and cardiorespiratory disease (Box 10.2). The term ‘Ogilvie's syndrome’ is loosely used in the literature as a synonym for ACPO, although it was actually used first to describe the pseudo-obstruction associated with retroperitoneal malignant infiltration. The mortality rate of ACPO is high, partly as a result of the underlying disorders but also related to failure to recognise the condition, leading to inappropriate operation. The true incidence is hard to ascertain since a number of unrecognised cases are likely to resolve spontaneously and diagnostic criteria are variable. However, it has been estimated that some 200 deaths per annum in the UK may result from ACPO.28

 

Box 10.2   Predisposing conditions in acute colonic pseudo-obstruction

Chest infection

Myocardial infarction

Cerebrovascular accident

Renal failure

Puerperium

Retroperitoneal malignancy (Ogilvie's syndrome)

Orthopaedic trauma

Myxoedema

Electrolyte disturbance

Aetiology

The state of colonic motility at any point in time is determined by a balance of the inhibitory influence of the sympathetic nervous supply and the stimulatory effect of the parasympathetic system. It has been suggested that ‘neuropraxia’ of the sacral parasympathetic nerves may be a factor in the aetiology of ACPO, leading to a failure of propulsion in the left colon. This would also explain the ‘cut-off’ between dilated and collapsed bowel, which is located on the left side of the large bowel in 82% of patients.29 Many of the conditions commonly associated with ACPO, such as sepsis, are likely to result from sympathetic overactivity.

Presentation

The clinical features of ACPO are almost identical to those of mechanical large-bowel obstruction, making differentiation on clinical grounds alone almost impossible. In a review of 400 patients it was noted that the clinical features of ACPO were abdominal pain (83%), constipation (51%), diarrhoea (41%), fever (37%) and abdominal distension (100%).29 On examination, the abdomen is generally very distended and tympanitic, but tenderness is often less than expected. The majority of patients will already have had operative procedures or have been hospitalised for some time because of some other disorder, and serum electrolytes are often abnormal.

Investigation (see also Chapter 5)

Plain radiographs of the abdomen in ACPO typically show gross distension of the large bowel with cut-off at the splenic flexure, rectosigmoid junction or, less commonly, the hepatic flexure (Fig. 10.7). Gas–fluid levels are less commonly seen on the plain radiograph in patients with ACPO compared with those presenting with mechanical obstruction.30 It has been suggested that a prone lateral view of the rectum may be useful in making the diagnosis since gaseous filling of the rectum will tend to exclude mechanical obstruction. The caecal diameter should be measured on sequential abdominal radiographs since it is believed that the risk of caecal rupture increases greatly with increasing caecal diameter.30

FIGURE 10.7 Plain abdominal radiograph of a patient with acute colonic pseudo-obstruction.

 

There is overwhelming support for the use of a contrast enema in all patients with suspected ACPO in order to establish the diagnosis, since the differentiation from mechanical obstruction can be extremely difficult. This is well illustrated in a study reported by Koruth et al., who performed a contrast enema on 91 patients with suspected large-bowel obstruction.31 Of the 79 patients who were thought clinically to have mechanical obstruction, the diagnosis was confirmed in 50. There was free flow of contrast to the caecum in the remaining 29 patients. Of these 29, 11 had non-obstructing colonic pathology such as diverticular disease and ulcerative colitis and 18 patients had pseudo-obstruction. Of the 12 patients who were thought to have pseudo-obstruction before the water-soluble contrast enema, two were shown to have carcinoma of the colon.

Management

The initial management of ACPO is non-operative and the underlying cause is treated if possible. Any medications that cause gut stasis should be discontinued, particularly analgesics. A nasogastric tube is routinely inserted to prevent swallowed air from entering the intestine and the use of enemas and flatus tubes is said to be of value in the treatment of early colonic pseudo-obstruction; in a number of patients even the water-soluble contrast enema used to establish the diagnosis may have a useful therapeutic effect. In most patients, the condition will resolve without intervention. One study found that it took an average of 6.5 days for complete resolution to take place in a group of 26 patients treated medically.30 Progress should be checked by serial examination of the abdomen and by abdominal radiographs.

It is only when the risk of perforation increases substantially that more active intervention becomes necessary. The risk of perforation is approximately 3% and it has been shown that there is a correlation between perforation and the duration of distension.32 The mean duration of distension was 6 days in the group of patients who went on to perforate compared with a mean duration of only 2 days in the group that did not progress to perforation.

 

In a randomised, double-blind, controlled trial of neostigmine only, 10 of 11 patients who were treated with intravenous neostigmine had prompt passage of flatus or stool, with reduced abdominal distension, compared with none of 10 patients who received placebo injection.33

These results were mirrored in a trial of 28 patients, with rapid resolution in 26. Time to pass flatus varied from 30 seconds to 10 minutes. In the two patients who failed to resolve, one was found to have a sigmoid cancer and the other died of multi-organ failure.34 There is a risk of bradycardia with cholinergic agonists, and it has been suggested that patients with cardiac instability should not be treated with neostigmine. Interestingly, there is anecdotal evidence that the concomitant administration of glycopyrrolate with neostigmine seems to offset the risk of bradycardia and may be considered in patients with cardiac instability.35 Epidural anaesthesia blocks sympathetic outflow, and improvement has been observed in a number of patients with ACPO who have had this form of treatment.36

The use of colonoscopy to decompress the colon in ACPO has become well established and it is successful in 73–90% of patients.37 The procedure can be difficult and tedious, requiring a skilled colonoscopist, and air insufflation must be kept to a minimum. Frequent small-volume irrigation is required to ensure good visibility in the colon and maintain the patency of the colonoscope suction channel. A further advantage of colonoscopy is that necrotic patches can be identified on the colonic mucosa, allowing pre-emptive surgical treatment before perforation supervenes. The risk of perforation of the colon during colonoscopy for this condition has been estimated at around 3%,38 and other complications are very unusual. It should be emphasised, however, that radiographs taken after successful clinical response often fail to show complete resolution of caecal distension, and one disadvantage of colonoscopic treatment is the tendency for the condition to recur. The overall rate of recurrence following initial colonoscopic decompression varies from 15% to 29%.39 There is some difference of opinion about the best method of management of recurrent ACPO, but the safety and efficacy of repeat colonic decompression has now been reported.27,37,39 A potential means of avoiding recurrence is intubation of the caecum with a long intestinal tube passed alongside the colonoscope.40

The indications for surgery include the following:

  1. Caecal distension – the extent of distension varies between authors, from 9 to 12 cm,41the threshold rising with increasing availability of medical therapy.
  2. Continuing caecal distension beyond 48–72 hours despite maximum medical therapy.
  3. Pain over the right iliac fossa, i.e. the caecum.
  4. Pneumoperitoneum.

There are doctors who recommend percutaneous caecostomies,42 where a tube is inserted into the caecum using radiological guidance for the purpose of decompression. A trephine caecostomy may be performed under local anaesthesia. To avoid contamination, the caecum can be sutured to the incised external or internal oblique muscles and only opened when the peritoneal cavity is sealed off. Only when perforation of the caecum is suspected should a full laparotomy be performed. If a perforation or necrosis of the caecum has already occurred, a full laparotomy is necessary and a right hemicolectomy is the treatment of choice. When resection of the right colon is required, it is probably safest to bring out an ileostomy and mucous fistula and reanastomose the two ends of bowel at a later date. Primary anastomosis may be feasible if contamination of the peritoneal cavity is not a feature and the remaining colon looks healthy.

Malignant Large-Bowel Obstruction

Approximately 85% of colonic emergencies are due to colon cancer and most of these occur in the elderly patient.43 However, only 8–29% of colorectal cancer patients present with intestinal obstruction.44 Approximately half of splenic flexure tumours present with obstruction, compared to 25% of those in the left colon, 6% of rectosigmoid lesions and 8–30% of right-sided carcinomas.45 Both obstruction and perforation occur together in approximately 1% of all colon cancers, but in patients who have an obstruction caused by cancer, 12–19% will have a perforation.44 The perforation may either be at the site of the tumour or in the caecum, caused by back pressure from the distal obstructing lesion.

The influence of obstruction on prognosis is controversial. Some studies suggest that the apparent adverse effect of obstruction on prognosis is a consequence of the stage of the disease rather than obstruction itself, as 27% have liver metastasis at the time of operation.46 Other reports, however, suggest that obstruction is an independent predictor of poor prognosis.47

Presentation

Symptoms associated with large-bowel obstruction frequently reflect the site of the tumour. In right-sided obstruction, particularly at the level of the ileocaecal valve, the onset of colicky central abdominal pain may be quite sudden and vomiting a relatively early feature. If the obstruction is at the rectosigmoid junction, there may be a history of a change in bowel habit and of rectal bleeding, with vomiting uncommon.

On examination, abdominal distension is the most notable feature. Peritoneal irritation suggests that perforation is either imminent or may have already occurred. Palpation of an irregular liver edge suggests that liver metastasis may be present and a palpable mass on rectal examination obviously suggests a carcinoma of the rectum.

Investigation

Plain abdominal radiography will usually provide the diagnosis of large-bowel obstruction. The pattern of gas distribution in both the small and large bowel will depend on the site of obstruction and also on whether the ileocaecal valve is competent. However, as already mentioned, differentiation from ACPO requires a contrast enema.

 

A water-soluble contrast enema (Fig. 10.8) should be carried out in all patients with suspected large-bowel obstruction without evidence of perforation.31

FIGURE 10.8 Water-soluble contrast enema demonstrating complete obstruction in the proximal sigmoid colon.

A water-soluble contrast enema will exclude other conditions such as volvulus or pseudo-obstruction and, in addition, may go some way to cleansing the colon distal to the obstructing lesion. Sigmoidoscopy or colonoscopy can be useful, particularly if the suspected obstructing lesion is in the distal colon. In addition, either technique can be used to exclude synchronous carcinoma or adenoma below the level of obstruction. CT with intravenous and water-soluble rectal contrast is increasingly used in the emergency setting and this has the added advantage of providing information on the spread of disease preoperatively (Fig. 10.9).

FIGURE 10.9 CT scan of a patient with a perforated caecum (perforation indicated by arrow). The scan also revealed an obstructing splenic flexure tumour and extensive liver metastases.

Management

The morbidity and mortality rate associated with emergency procedures for obstruction of the colon is at least twice that for elective surgery. This has encouraged surgeons to develop methods such as the use of expandable intraluminal stents. These can be used to palliate patients or to convert emergency operations into elective procedures. Several colonic stents are currently available and can be placed using radiological or endoscopic assistance. Various models can be deployed over guidewires or through an endoscope.

A review of 54 case series that included 1198 patients48 found that in 791 palliative patients, technical success was possible in 93% and clinical success (defined as decompression in less than 48 hours) in 91%. Stents also provided successful conversion to elective procedures in 92% of 407 patients. Intraluminal stenting was more successful in shorter, distal lesions and colonic primaries. Technical failure usually results from an inability to pass the guidewire or stent catheter across the lesion. Reported complications include perforation in 3.8%, stent migration in 12% and re-obstruction in 7%.

When surgery is undertaken, patients with right-sided obstruction should be positioned flat on the operating table. Those with left-sided large-bowel obstruction are placed in the lithotomy/Trendelenburg position to allow access to the anus during the procedure for purposes of irrigation of the rectal stump or anal insertion of a surgical stapling instrument. It also allows the surgical assistant the option of standing between the patient's legs. The abdomen is opened through a midline incision. If the bowel is tense, it should be decompressed: first, to improve visualisation of the rest of the abdomen and, second, to prevent spillage of faecal content. The large bowel can be decompressed by inserting a 16 G intravenous catheter or 18 F nasogastric tube obliquely through the colonic wall, following which suction is applied. This is often enough to make it possible to handle the large bowel without fear of rupture as the distension is mainly gas. After localisation of the primary tumour, synchronous tumours should be excluded. The presence of direct spread to adjacent structures should also be assessed, in addition to any peritoneal seedlings and the presence of liver secondaries. Based on these observations, a decision can be made as to whether the operation is potentially curative or palliative.

When there is a prospect of curative resection, standard techniques of radical cancer therapy should be employed, including wide excision of the lesion en bloc with the appropriate blood vessels and mesentery. If the lesion is adherent to other structures, an attempt should be made to resect the affected part en bloc. High cure rates are possible with locally advanced tumours if a radical resection is performed and clear resection margins obtained. The presence of liver or peritoneal metastases does not preclude resection of the primary carcinoma and gastrointestinal continuity should be restored if at all possible.

If there is a closed loop obstruction because of competence of the ileocaecal valve, the caecum and right colon may be very tense. Decompression can be achieved as a preliminary to resection by making a small enterotomy in the terminal ileum and passing a Foley catheter through the ileocaecal valve into the caecum. This technique is particularly useful in situations where there is splitting of the taenia on the caecum, indicating impending rupture. The range of operations available for treatment of right-sided tumours causing obstruction includes right hemicolectomy with primary anastomosis, right hemicolectomy with exteriorisation of both ends of the large bowel, and ileo-transverse colon bypass. There is general agreement that a right hemicolectomy with primary anastomosis is the treatment of choice in most patients; however, this procedure is by no means free of complications. One report noted an operative mortality rate of 17% in 195 patients who had emergency right hemicolectomy with primary anastomosis for obstructing colonic carcinoma.49 In addition, a leak rate of 10% was noted in 179 patients who had a right hemicolectomy and primary anastomosis for obstruction. This compares with a leak rate of 6% in 579 patients with right colon cancer who did not have an obstruction.49 Other studies have shown similar mortality rates, and many of the deaths resulted from anastomotic failure. This suggests that instead of subjecting all patients with obstruction to right hemicolectomy with primary anastomosis, it may be wiser to use a policy of selection, subjecting patients with good risk status to primary anastomosis and managing patients with risk factors for anastomotic failure by resection and exteriorisation of the bowel ends.

The anastomotic technique used will depend on the surgeon's preference. If the obstructed bowel is very thickened and oedematous, care should be taken with the use of stapling instruments since there is a tendency for the instruments to cut through oedematous bowel. On these occasions a sutured anastomosis is preferable. Only on the relatively rare occasion when locally advanced disease is unresectable should the patient be subjected to an ileo-transverse colon bypass procedure. There is almost no place for caecostomy in the current management of right-sided large-bowel obstruction; trephine ileostomy, which can usually be achieved under local anaesthesia, affords better palliation in very sick patients not fit for operation under general anaesthesia.

Most surgeons would advocate an extended right hemicolectomy for patients with transverse colon carcinoma, and decompression of the colon may be necessary to facilitate mobilisation. For the patient who has a large carcinoma obstructing the transverse colon, achieving clearance may be difficult because of involvement of the transverse mesocolon and adjacent organs. The splenic flexure is mobilised to assist with a primary anastomosis between ileum and upper descending colon. In the sick patient who already has a perforated caecum, resection and an ileostomy may be appropriate.

For obstructing left-sided colonic tumours, the two most frequent options are resection and either primary anastomosis, or colostomy and rectal closure (Hartmann's procedure). A three-stage procedure (diverting colostomy, resection and colostomy closure) is now rarely used, and only in critically ill patients. Two-stage procedures became popular during the 1970s and remain the procedure of choice for most surgeons, with an overall mortality around 10%.44 However, the main disadvantage of this approach, apart from the fact that a second operation is required for reconstruction, is that approximately 40% of patients will be left with a permanent stoma.

The second stage of the two-stage operation may be difficult because of adhesions, although it is facilitated if the rectal stump has been divided above the peritoneal reflection. The timing of the second stage is also important and most surgeons will wait 2–6 months. The second stage of the two-stage procedure is increasingly being performed using laparoscopic techniques. If successful the hospital stay is reduced, but conversion to open surgery may be necessary.

Primary resection and anastomosis is associated with a shorter hospital stay, reduced mortality and morbidity, and the avoidance of a stoma. It is increasingly becoming the operation of choice for colorectal surgeons, with the exact procedure depending on a number of factors. Subtotal colectomy followed by ileosigmoid or ileorectal anastomosis has been reported to have a low operative mortality of 3–11% and a hospital stay of around 15–20 days.50 Segmental colectomy (left hemicolectomy, sigmoid colectomy or anterior resection of the rectosigmoid) with on-table irrigation followed by primary anastomosis has a reported operative mortality rate around 10%, anastomotic leakage around 4% and hospital stay of approximately 20 days.51

A retrospective study of 243 patients who underwent emergency operation for obstructing colorectal cancers showed that primary resection and anastomosis for left-sided malignant obstruction either by segmental resection with on-table lavage or by subtotal colectomy was not more hazardous than primary anastomosis for right-sided obstruction.52 Single-stage resection with primary anastomosis was possible in 197 patients. Of the 101 patients with left-sided obstruction, segmental resection with on-table colonic lavage was performed in 75 patients and subtotal colectomy in 26. There were no differences in the mortality or leakage rates between patients with right-sided and left-sided lesions (mortality 7.3% vs. 8.9%; leakage 5.2% vs. 6.9%, respectively).

More recent papers have described segmental resection and primary anastomosis without any attempt to clean the bowel. One study reported only one leak and one postoperative death in 58 consecutive patients with left-sided malignant colonic obstruction who underwent bowel decompression without irrigation, followed by resection and primary colocolic anastomosis.53 The patients in this study had a mean age of 63 (range 54–89) years, the leak occurring in a 61-year-old with a sigmoid carcinoma and the death in an 80-year-old due to myocardial infarction. None of the carcinomas described were rectosigmoid or rectal. A further study of left-sided obstruction in which 40 of 60 patients had carcinoma compared one-stage resection with Hartmann's procedure.54 There was no significant difference in outcome or time taken to complete the operation, with the only death being in the Hartmann's group. Again, none of the tumours described was more distal than the sigmoid colon.

Circumstances usually dictate the operative choice. In the elderly, segmental resection may be preferable to a more extensive resection, both in terms of operative morbidity and postoperative problems of incontinence. Subtotal colectomy is clearly the procedure of choice when there are synchronous tumours in the colon. When subtotal colectomy with ileorectal anastomosis is selected as the operation of choice, the whole colon is mobilised and the rectum washed out as for elective surgery. After resection of the colon, an ileorectal or ileosigmoid anastomosis is performed using either a sutured or stapled technique. The first randomised trial comparing subtotal versus segmental resection was reported in 1995.55 This study involved 91 eligible patients recruited by 18 consultant surgeons in 12 centres; 47 were randomised to subtotal colectomy and 44 to on-table irrigation and segmental colectomy. There was no significant difference in operative mortality, hospital stay, anastomotic leakage or wound sepsis between the two groups. There was, however, a significantly higher permanent stoma rate in the subtotal colectomy group compared with the segmental colectomy group (7 vs. 1). The high permanent stoma rate in the subtotal colectomy group was partly accounted for by four patients who were randomised to subtotal colectomy but who underwent Hartmann's procedure because this was thought clinically more appropriate at the time of surgery by the operating surgeon. Two additional patients had the anastomosis taken down at a later date and a stoma formed. At follow-up 4 months after the operation, there was a significantly greater number of patients who had three or more bowel movements a day after subtotal colectomy than after segmental resection (14 of 35 vs. 4 of 35). One patient had 12 bowel movements per day after subtotal colectomy. Nearly one-third of patients randomised to subtotal colectomy had night-time bowel movements during the first few months after operation. In contrast, less than 10% of those who had segmental resection had this problem.

 

Segmental resection of the colon, with or without intraoperative irrigation, is the preferred treatment for left-sided malignant colonic obstruction.55,56

Although the SCOTIA study55 addressed the immediate and early results after these two procedures, it did not investigate the long-term implications of either procedure. It has been argued that there are advantages in performing a subtotal colectomy rather than segmental resection because synchronous tumours will be removed along with the obstructing lesion and, since the length of colon left is small, there should be less risk of developing a metachronous tumour. Clearly the operating surgeon needs to take all these factors into account when making the final decision on which procedure is most suitable for the individual patient.

Inflammation and infection

Acute Colonic Diverticulitis

Colonic diverticula are found with increasing age. It has been estimated that one-third of the population will have colonic diverticula by the age of 50 years and two-thirds after 80 years. Although the vast majority of individuals with colonic diverticula are asymptomatic, most patients who require surgical care do so because of an inflammatory complication. Acute diverticulitis can affect any part of the colon; in Western Europe and North America, the left side is more commonly affected, whereas in Japan and China right-sided diverticulitis is more commonly seen. Symptomatic complications of diverticulitis occur in 10–30% of patients, but the need for surgery in acute diverticulitis is becoming less common.

Presentation

Diverticulitis is thought to result from inspissation of stool in the neck of a diverticulum, with consequent inflammation and possible microperforation. This results in local bacterial proliferation, leading to inflammation in the surrounding colonic wall and mesentery (acute phlegmonous diverticulitis). A collection of pus may form either in the mesentery of the colon or adjacent to the colonic wall. As the collection of pus enlarges, it becomes walled off by loops of small bowel or the peritoneum of the pelvis. Occasionally, free perforation into the peritoneal cavity occurs with consequent purulent or faecal peritonitis. The Hinchey grading system for acute diverticulitis has become fairly widely accepted, allowing more meaningful comparison between outcome studies (Table 10.1).57

Table 10.1

Hinchey classification of peritoneal contamination in diverticulitis

Stage 1

Pericolic or mesenteric abscess

Stage 2

Walled-off pelvic abscess

Stage 3

Generalised purulent peritonitis

Stage 4

Generalised faecal peritonitis

From time to time other complications also arise. A fistula sometimes develops between bowel and another adjacent organ (ie. the bladder or vaginal cuff). Diverticular disease is responsible for around 10% of all cases of left-sided large-bowel obstruction and is frequently difficult to differentiate from malignant left-sided large-bowel obstruction on clinical grounds. Bleeding also occurs.

There has been controversy regarding the virulence of diverticular disease in younger patients and the possible increase in need for surgical intervention in this group. Recently, Biondo et al. looked at 327 patients treated for acute left colonic diverticulitis and compared those aged 50 or less with those older than 50.58 No difference was noted regarding severity or recurrence. Another study found that diverticulitis in the young does not follow a particularly aggressive course.59 In general, there is a trend towards conservative management of acute diverticulitis, with early investigation and confirmation of the diagnosis being a fundamental part of this approach. The mortality and morbidity rates can be high if emergency surgery is necessary.

Investigation

Acute right-sided diverticulitis, a rare condition in the Western world, can be confused with appendicitis as it occurs in a somewhat younger age group than left-sided disease. In the more common left-sided disease, the plain abdominal radiograph may show non-specific abnormalities such as pneumoperitoneum, intestinal obstruction or a soft-tissue mass.

 

CT is now the favoured modality for acute investigation of suspected acute colonic diverticultis.60

Features of acute diverticulitis include thickening of the bowel wall, increased soft-tissue density within the pericolic fat secondary to inflammation and a soft-tissue mass, which represents either a phlegmon or an abscess. Advantages of CT include the accurate assessment of the extent of pericolonic involvement and the diagnosis of abscess formation or perforation (Fig. 10.10). It is also useful for tracking the therapeutic percutaneous drainage of any abscess. When CT is compared with barium enema, CT is no more accurate in terms of diagnosis but undoubtedly provides better definition of the extent and severity of the inflammatory process, which is of prognostic value in the short and long term.61 Ultrasonography has also been used for localised diverticulitis. The main disadvantages of ultrasonography are that assessment of bowel thickening is a non-specific finding and assessment is very operator dependent.

FIGURE 10.10 Appearance of perforated sigmoid diverticular disease on CT. The upper arrow shows a small pocket of free air and the lower arrow one of the diverticula.

An alternative investigation is contrast enema. Despite the extensive literature on the use of contrast enema in acute diverticulitis, there is no consensus on either the best contrast agent or the optimal timing of the examination. There has been some interest with magnetic resonance imaging in the diagnosis of acute diverticulitis and prospective observational studies have been encouraging, but more formal evaluation is still required.62

Management

Right-sided disease may be encountered unexpectedly at surgery or be operated on for a complication diagnosed preoperatively. The treatment options are controversial, ranging from appendicectomy to hemicolectomy. A conservative approach with appendicectomy and antibiotics has resulted in a similar mortality, morbidity and recurrence as for resection of the diverticulum.63 A right hemicolectomy is the correct operation when it is not possible to rule out the presence of a carcinoma.

A typical patient with localised left-sided diverticulitis will complain of pain in the left iliac fossa and will be febrile. Examination reveals tenderness and sometimes a mass is palpable per abdomen or on rectal examination. In women, a vaginal examination should also be performed to exclude gynaecological pathology. If sigmoidoscopy is performed, it should be done gently with minimal insufflation of air.

In the absence of generalised peritonitis, a non-operative policy is adopted, with antibiotic therapy directed against Gram-negative and anaerobic bacteria. Most clinicians advocate bowel rest initially, and intravenous fluids and antibiotics. If the pain and fever settle within a few days, the patient can go home on oral antibiotics and a barium enema and sigmoidoscopy or colonoscopy can be performed as an outpatient several weeks later to exclude any malignancy.

If the patient continues with fever, pain or enlarging lower abdominal mass, a CT should be obtained. If there is an abscess, it can be drained percutaneously under radiological guidance. In the event of localised abdominal signs becoming more generalised, or if there is a failure of the infective process to settle despite adequate non-operative therapy, operation is indicated. In the small number of patients who require operation for localised diverticulitis, primary resection, with or without on-table irrigation and primary anastomosis, is becoming increasingly popular among specialist colorectal surgeons.

Pain from perforated sigmoid diverticulitis usually commences in the lower abdomen, mostly on the left side, and gradually spreads throughout the abdomen. In 25% of patients, however, signs and symptoms are predominantly right-sided63 and in some patients might mimic acute appendicitis. On examination, there are signs of generalised peritonitis including guarding and rebound tenderness. About one-quarter of all patients will have free gas under the diaphragm on plain radiography, and at operation purulent peritonitis is more common than faecal peritonitis.64 The majority of patients presenting in this way will clearly require operation following adequate resuscitation. Antibiotic therapy should be commenced early to cover both anaerobic organisms and Gram-negative bacteria. Some patients will improve so much with non-operative treatment that it may be appropriate to continue with this therapy for a longer period.

Operative Management: The patient is placed in the lithotomy/Trendelenburg position and explored with a midline incision. Pus and faecal material should be removed from the peritoneal cavity and specimens sent for microscopy and both aerobic and anaerobic culture. Intraoperative irrigation of the peritoneal cavity with 6–10 L of warm saline solution is of value, while the addition of topical antibiotics to the solution (e.g. cephradine 1 g in 1 L of 0.9% saline), although logical, remains unproven.

In addition to treating the peritonitis, surgical treatment must minimise continued contamination of the peritoneal cavity. A review of 57 reports65 on the treatment of acute diverticular disease demonstrated that the operative mortality rates from procedures that involve primary resection (10%) were less than half those from operations that did not include excision of the diseased colon (20%). A further reason for advocating primary resection is the difficulty experienced at the time of operation in deciding whether the lesion is a perforated carcinoma or an area of diverticulitis. At laparotomy, the appearance of both lesions may be similar when the colon is inflamed and oedematous. It has been estimated that as many as 25% of patients with a preoperative diagnosis of perforated diverticulitis may be found to have a perforated carcinoma. If there is reasonable suspicion of carcinoma, a radical resection of the lesion, together with the colonic mesentery, needs to be performed. Examination of the resected specimen at the earliest opportunity is recommended to aid further decision-making.

Failure to take the resection far enough distally beyond the sigmoid colon risks recurrence of diverticular disease. Therefore, Hartmann's resection with complete excision of the sigmoid and closure of the rectum, with formation of a left lower quadrant colostomy, has been the standard procedure advocated by most surgeons. If the operation is exceptionally difficult owing to the colon being very adherent to surrounding structures, making safe mobilisation impossible, it may be reasonable to create a proximal stoma, drain the area and transfer the patient to a tertiary referral centre for more definitive treatment.

There has been an increase in the use of primary anastomosis in selected patients who have operations for acute diverticulitis. The main reasons are: (i) that patients receive one operation rather than two; (ii) after a Hartmann operation many patients are left with a permanent stoma, either because of unwillingness or unfitness to have further surgery; and (iii) reversal operation after Hartmann's resection can be very difficult.

One study reported resection, intraoperative colonic lavage and primary anastomosis in 55 of 124 patients with complicated diverticular disease; 49 of the 55 had diverticulitis, 33 having localised and 16 generalised peritonitis.66 Faecal peritonitis was considered a contraindication to a one-stage procedure. Four patients died, one from an anastomotic leak. Major complications included two anastomotic leaks (one of which was successfully treated with parenteral nutrition), four re-operations (three for abdominal wound dehiscence and one for anastomotic leak) and four deaths (three of those who died were over 70 years old). The study concluded that one-stage resection is feasible in selected patients.

 

One-stage resection for acute complicated diverticultis without faecal peritonitis is feasible and should be considered, depending on patient fitness.66

A further study of primary anastomosis in emergency colorectal surgery showed no significant difference in the incidence of complications, even in patients with free peritonitis (21.9% perforation, 17.7% localised sepsis).67 The necessity for intraoperative colonic lavage has also been challenged. Despite an increasing trend to perform primary anastomosis in patients who have perforated diverticulitis, the number of patients who are suitable for such a procedure will be small.

Laparoscopic techniques continue to be used in an increasing number of diverticular cases with good results,68 with laparoscopic assessment and lavage also a possibility. A recent review found laparoscopic peritoneal lavage for perforated sigmoid diverticulitis to be a potentially effective and more conservative alternative to a Hartmann procedure.69 Randomised controlled trials are needed to better evaluate its role.

Neutropenic Enterocolitis

Neutropenic enterocolitis, also known as typhlitis, is a potentially life-threatening condition characterised by an inflammatory process that usually involves the caecum and ascending colon. It occurs most often as a complication of chemotherapy and can progress to necrosis and perforation. Although it can affect any part of the small and large intestine, the cause of its predisposition for the right colon is unclear.

Clinical features include nausea, vomiting, abdominal pain, distension and diarrhoea, which can be bloody. Right iliac fossa tenderness and pyrexia are quite common and in later stages peritonitis may be present. CT is the diagnostic modality of choice and may reveal right-sided colon wall thickening, mesenteric stranding, pneumatosis and ascites (Fig. 10.11).

FIGURE 10.11 CT scan showing large retroperitoneal collection (indicated by arrows) secondary to acute necrotising enterocolitis with a delayed perforation of the posterior wall of the caecum and ascending colon.

Management demands careful evaluation of the patient, with each case treated individually. An initial conservative approach includes fluid and electrolyte replacement, broad-spectrum antibiotics, correction of any attendant coagulopathy and complete bowel rest with parenteral nutrition. The use of recombinant granulocyte colony-stimulating factor to correct chemotherapy-induced neutropenia should be considered. Colonic perforation and generalised peritonitis are clear indications for surgery. The operative procedure of choice is a right hemicolectomy, with either exteriorisation of the bowel ends or a primary anastomosis, depending on the extent of sepsis and peritoneal soiling. In general, most patients can be managed non-operatively.

Toxic Colitis

Toxic colitis is a potentially fatal complication of inflammatory bowel disease, particularly if accompanied by megacolon. While several schemes exist to accurately identify toxic colitis, one reasonably simple system employs a definition that includes a disease flare-up accompanied by two of the following criteria: hypoalbuminaemia (< 3.0 g/dL), leucocytosis (> 10.5 × 109cells/L), tachycardia (> 100 beats/minute), temperature elevation (> 38.6 °C).70 Use of this relatively objective definition may aid in the diagnosis and care of these patients, whose severe condition can be under-appreciated because of high dosages of steroids, immunomodulators or biological agents.

The initial management is directed at reversing physiological deficits with intravenous hydration, correction of electrolyte imbalances, and blood product transfusions. Free perforation, increasing colonic dilatation, massive haemorrhage, peritonitis and septic shock are indications for emergency operation after the patient has been adequately resuscitated. In the absence of these features, medical therapy is initiated with high dosages of intravenous corticosteroids, immunomodulators and/or biological agents. Broad-spectrum antibiotics directed against intestinal flora are prescribed to minimise the risk of sepsis secondary to transmural inflammation or microperforation. Anticholinergics, antidiarrhoeals and narcotics are avoided as they may worsen already impaired colonic motility or conceal ominous symptoms. Hyperalimentation may be started and the patient is closely observed with serial examinations and abdominal roentgenograms. Any worsening of the clinical course over the ensuing 24–72 hours mandates urgent laparotomy. If the patient improves minimally after 5–7 days of conventional therapy, the medical therapy should be altered or surgery should be advised. Experience with ciclosporin or infliximab in this setting is anecdotal, and should be weighed against operative therapy while understanding that surgery in this setting often relegates the patient to an ileostomy.71

The principal operative options in patients with toxic colitis are subtotal colectomy with end ileostomy or loop ileostomy with decompressive blowhole colostomy. The most difficult aspect of a subtotal colectomy is managing the distal bowel stump. The distal limb may be closed with sutures or staples and then delivered to the anterior abdominal wall, where it can lie without tension in the subcutaneous fat of the lower midline wound. If the bowel end is placed above the fascia, dehiscence of the rectal closure during the postoperative period results in a mucous fistula. If the closed stump is left within the peritoneal cavity, staple line dehiscence will produce a pelvic abscess. If the bowel wall is too friable to hold sutures or staples, creation of a mucous fistula is preferred. If there is inadequate residual bowel length to create a mucous fistula, many surgeons will place a catheter through the anus (e.g. Mallencott or Foley) to decompress the rectum and reduce the chance of a stump blowout.

The patient typically improves over the ensuing few days and can be discharged within a week of the operation. An appropriate elective procedure can be considered several months after the patient recovers.

Proctocolectomy with end ileostomy is rarely performed in the severely ill patient with toxic colitis because of the excessive rates of morbidity and mortality.72 Proctectomy increases the difficulty of the procedure and risks pelvic bleeding as well as autonomic nerve damage. In rare instances of rectal perforation or profuse colorectal haemorrhage, proctocolectomy may be an option. The surgeon must be cautioned, however, that the macroscopic and microscopic differentiation of ulcerative colitis from Crohn's proctocolitis is especially difficult in severe colitis, and primary proctocolectomy would nullify the future option of a restorative procedure in a patient with ulcerative colitis.

The need for loop ileostomy combined with decompression blowhole colostomy has virtually disappeared with improved medical recognition and more sophisticated management of toxic colitis. The operation is still useful in extremely ill patients or those in whom colectomy would be especially hazardous (e.g. contained perforation, high-lying splenic flexure and pregnancy). Contraindications to the procedure include colorectal haemorrhage, free perforation and intra-abdominal abscess. The operation is considered only a temporising procedure, and a definitive operation is commonly performed approximately 6 months later.

Perforation

Stercoral Perforation

The word stercus means dung or faeces. Perforation of the bowel caused by pressure necrosis from a faecal mass is a rare entity, first reported by Berry at the Pathological Society of London in 1894. Fewer than 100 cases have been reported in the literature, although this may reflect the poor outcome (with mortality rates approaching 50%), an increasing reluctance to publish case reports and ill-defined diagnostic criteria. There appears to be an equal incidence in men and women and the median age for these patients is said to be 60 years.73

Reported predisposing factors have included chronic constipation, megacolon, scleroderma, hypercalcaemia, renal failure and renal transplantation. Medications associated with stercoral perforation include narcotics, postoperative analgesia, antacids, calcium channel blockers and antidepressants. Only 11% of cases are accurately diagnosed prior to operation,74with investigations frequently non-contributory. Perforations usually occur on the antimesenteric border, with the majority occurring in the sigmoid colon and rectosigmoid region. Multiple perforations are found in about one-fifth of patients, with the remaining patients usually having ulceration extending away from the perforation.

The suggested clinicopathological diagnostic criteria are:

  • A round or ovoid colonic perforation exceeding 1 cm in diameter.
  • Faecolomas present within the colon.
  • Microscopic evidence of pressure necrosis or ulcer and chronic inflammatory reaction around the perforation site.75This study, which constitutes one of the largest single-institution reports on stercoral perforation of the colon, defined strict clinical and pathological criteria for its diagnosis. Using these criteria stercoral perforation of the colon would appear to occur more frequently than previously reported in the literature.

Management of these patients is surgical, with the resection margins sufficiently wide to encompass all areas of perforation or impending perforations. The bowel is universally loaded with stool and the tendency towards constipation is not removed by a limited resection. The operation should involve resection of the affected segment and exteriorisation of the bowel for left-sided perforations, with resection and primary anastomosis being reserved for those patients with a right-sided perforation. The risk of recurrent perforation in the proximal colon presents a further problem for those with a left-sided perforation. Milking the stool in an antegrade direction into the resected segment and orthograde colonic irrigation may combine to avoid early re-perforation. However, the fear of recurrent perforation from persistent constipation has led some surgeons to suggest a subtotal colectomy.

Anastomotic Dehiscence

Breakdown of an anastomosis is one of the most significant complications after large-bowel surgery. The presentation can be insidious but more commonly the patient becomes acutely ill, particularly if there is generalised peritonitis. If the diagnosis is not made and appropriate treatment undertaken, death is likely to follow. There is no doubt that the presence of anastomotic leakage significantly increases mortality and one study noted a mortality rate of 22% in 191 patients who had leakage after large-bowel anastomosis compared with only 7.2% in 1275 patients without a leak.76 In the patients who survive this serious complication, morbidity and hospital stay are greatly increased.

Causes

A variety of general and local causative factors of anastomotic dehiscence have been described. General factors listed usually include poor nutritional state, anaemia, uraemia, diabetes, steroid administration and old age, while suggested local factors involved tension, ischaemia or infection of the anastomosis. The risk of anastomotic leakage in low colorectal anastomosis is several times higher than in either ileocolic or colocolic anastomosis. In one report a clinical leak rate for ileocolic and colocolic anastomosis was 0.4%, whereas the leak rate after low colorectal anastomosis was 4.7%.77 In a review of 477 large-bowel anastomoses, which included 215 colorectal anastomoses, there were eight colorectal and one ileocolic leaks. All nine patients required laparotomy, and seven were salvaged with no mortality. Three colorectal leaks (small posterior defects in stapled anastomoses) were closed with interrupted endoanal sutures and a proximal loop stoma fashioned in two patients who did not already have one. The other two leaks (defect in suture line attributable to a single suture cutting through) were managed by creating a controlled external fistula. None of these patients had further complications and all the stomas were subsequently closed. It is therefore possible to salvage anastomotic leaks with a good outcome in selected patients with appropriate operative treatment.

Another important factor in dehiscence is the oxygen tension at the bowel ends used for the anastomosis. In an elegant study reported in 1987, it was shown that if tissue oxygen tension in the ends of bowel to be anastomosed fell to less than 20 mmHg (2.66 kPa), there was a high likelihood of anastomotic breakdown.78 However, a significant factor in anastomotic failure is poor surgical technique, irrespective as to whether sutures or staples are used.

Presentation

In general, the clinical features of anastomotic dehiscence will depend on whether the leak is localised or more extensive, causing generalised peritonitis. At one end of the spectrum, when sepsis associated with the leak is localised, the patient may have minimal symptoms and only a few physical signs. There may be ‘flu-like’ symptoms of feeling vaguely unwell with shivering and nausea. If the anastomosis lies low in the pelvis, there may be some lower abdominal pain and tenderness and on rectal examination a defect can often be felt in the anastomosis. Tachycardia is a common general feature and is often associated with pyrexia. If a drain is still in situ, faecal material or pus may be seen.

At the other end of the spectrum the scenario is associated with a major leak, when faecal material or pus has leaked into the general peritoneal cavity. The effect on the patient is usually profound. Abdominal pain is difficult to control and tachycardia and tachypnoea are common. The temperature is raised and hypotension is often a feature. The patient is distressed and sweaty and on abdominal examination the abdomen is tender with abdominal guarding. Sometimes the features of even an extensive leak can be more insidious, with the patient not making progress as rapidly as expected and suffering abdominal pain that is vague rather than dramatic.

Delay in diagnosis of large-bowel anastomotic leakage is still a major problem and leads to increased morbidity and mortality. It is crucial that surgeons are vigilant about deterioration of any patient who has a large-bowel anastomosis and maintain a low threshold for ordering investigations to identify a leak. It should be remembered that the anastomosis may leak any time during the first 2–3 weeks after operation.

Investigations

Usually the white blood count is elevated, except in patients who have overwhelming sepsis, when it may be either normal or even low. However, the earliest derangement in the white blood count is an increase in the less mature polymorphic neutrophils (e.g. left shift). Erect chest radiograph or abdominal films will sometimes show gas under the diaphragm, but this sign is of debatable significance in the first few days after the original operation because of the presence of intra-abdominal air introduced at the time of operation. The absence of pneumoperitoneum should not discourage the clinician from pursuing investigations to check the integrity of the anastomosis.

Ultrasound examination can be helpful in the patient with a suspected collection of pus related to anastomotic leakage, but the value of this investigation is often impaired by the presence of dilated gas-filled loops of bowel, with dressings and drains on the abdomen further increasing technical difficulties. CT or contrast studies are the investigation of choice.

Water-soluble contrast enema is a simple investigation for assessing anastomotic leakage, particularly on the left side of the large bowel. Another option is a pelvic CT scan with rectal contrast. In addition to demonstrating whether a leak has occurred, assessment of the extent of leakage is of value in deciding the overall management. It is important to be aware of two caveats, however. Occasionally, when the contrast study shows no leak, a later investigation will show one. The corollary of this is also sometimes true. The enema or scan may show a leak that is of no clinical consequence (radiological leak). It is therefore important to look at the overall clinical picture and attempt to assess all the clinical and radiological evidence before coming to a final conclusion about the presence of a clinically significant leak.

Management

Although the literature on colonic anastomotic leak rates is extensive, there is a paucity of information on how to treat the leakage. It is best to consider the management of localised leakage separately from those who present with generalised peritonitis. Most patients with localised leakage can be treated non-operatively with bowel rest and antibiotic therapy. If there is a large collection of pus around the anastomosis, it is usual to drain this percutaneously under ultrasound or CT guidance. Patients with generalised peritonitis from a large-bowel anastomotic leak are usually dramatically ill and require resuscitation. Assuming that investigations have been performed and the diagnosis confirmed, the next step is to improve the patient's condition before surgical intervention.

Haemodynamic status needs to be assessed and treatment given to improve cardiac and respiratory function. Parenteral antibiotic administration is a priority and inotropic support may be necessary. Adequate pain control is important and these patients are best managed in a high-dependency unit or intensive therapy unit. Anaesthesia is alerted and only when the patient's condition is stabilised is operation undertaken.

The patient is usually placed in the lithotomy/Trendelenburg position. The previous midline incision is reopened and great care is taken not to damage adherent loops of small intestine. Bowel loops are dissected free and the area of anastomosis exposed. Faecal material and pus are removed from the peritoneal cavity and pelvis. Occlusion clamps are gently placed on bowel above and below the leaking anastomosis to limit further contamination. Extensive lavage of the peritoneal cavity is performed with saline or antibiotic solution.

The next steps depend on the size and location of the anastomotic defect. In the majority of cases, the anastomosis is taken apart and the proximal end of bowel is brought out as an end stoma and the distal end as a mucous fistula. If the distal stump is not long enough to be brought out on the abdominal wall, it should be closed carefully using a series of interrupted seromuscular sutures. Some surgeons will place a transanal drain to decompress the bowel. Surgeons must be aware that the more distal the leak, the lower the chances of bowel continuity being restored at a later date.

In selected patients (usually those with a small defect in a low colorectal anastomosis), the anastomosis may be salvaged. A defunctioning ileostomy can be constructed for diversion and the area of the leak can be drained. However, the faecal loading in the colon can lead to continued soiling unless it is removed with transanal irrigation. However, in a patient who has already had an anastomotic leak it is poor practice to risk a further leak and the patient's safety should be the prime objective.

Bowel Damage At Colonoscopy

The perforation rate at colonoscopy is now generally agreed to be about 1 in 500, varying with the level of intervention employed.

There are three proposed mechanisms for colonoscopic perforation:

  1. mechanical perforation directly from the colonoscope or biopsy forceps;
  2. barotrauma from overzealous air insufflation;
  3. perforations occurring as a result of therapeutic procedures (use of energy sources).

Measurement of forces exerted during colonoscopy has only been reported in one paper from the Royal London Hospital,79 where an electronic device was used in a research setting. The caecum and right colon are most susceptible to barotrauma, although diverticula can also be directly inflated. The use of carbon dioxide for insufflation may decrease perforation rates and increase levels of patient comfort. Therapeutic interventions such as polyp removal with a hot biopsy or snare and balloon dilatation of strictures are, not surprisingly, associated with a higher risk of perforation.

The most common site of perforation is the sigmoid colon. Signs and symptoms of a perforation are not always obvious at the time of colonsocopy. In retrospective studies, the diagnosis of a perforation is delayed in about 50% of patients.80 If the endoscopist is worried after an examination has been completed, an erect chest radiograph should be ordered as a screening test and the patient observed until symptoms have settled. In cases where there is a high index of suspicion, a water-soluble enema or CT scan with contrast can be used to confirm the diagnosis.

Non-operative treatment with close observation, intravenous fluids and antibiotics may be possible in selected patients.81 The authors' approach is presented in Fig. 10.12. A large defect or symptoms of peritoneal contamination will usually require operative treatment. If the injury is operated upon early, a direct repair of the defect or small resection and a primary anastomosis is possible. It may also be possible to effect the repair laparoscopically. With delayed diagnosis or clinical deterioration during observation, patients will usually require a temporary defunctioning stoma.

FIGURE 10.12 Algorithm for the management of colonoscopic perforation.

Colonic bleeding

Although upper gastrointestinal and small-bowel bleeding has been covered in Chapters 5 and 7, there remains the problem of patients who bleed from the colon. In approximately 20% of cases, the colon and rectum are the source of acute gastrointestinal haemorrhage. The most common aetiologies of this haemorrhage include diverticulosis, angiodysplasia, ischaemic colitis, inflammatory bowel disease, neoplasms, aorto-enteric fistulas and anorectal diseases such as haemorrhoids.82 The general principles of management of many of these conditions have already been discussed, but each patient needs to be managed individually. Where possible, management of colonic bleeding is non-operative and usually stops spontaneously, permitting investigation to proceed at a leisurely pace. In some patients, however, the bleeding either does not spontaneously stop or is profuse and urgent investigation, followed occasionally by emergency surgery, is required. In these patients, the source of bleeding is often difficult to identify.

Diagnosis And Non-Surgical Management

Diagnostic tests utilised will vary according to institutional availability, patient characteristics, and the providers' experience and expertise. These investigations are used to localise the site of haemorrhage, cause it to stop or confirm its cessation. Options include radionuclide imaging, colonoscopy, CT angiography and selective angiography.

Radionuclide imaging

Radionuclide imaging with [99mTc]pertechnetate-tagged red cells detects the slowest bleeding rates (0.1–0.5 mL/min) but cannot reliably localise the site of haemorrhage.83

The timing of the radionucleotide blush is important. An immediately positive blush (within the first 2 minutes of scanning) is highly predictive of a positive angiogram (60%) and the need for surgery (24%), while a negative scan is highly predictive of a negative angiogram (93%) and the need for surgery falls to 7%.84 A negative nuclear scan provides objective evidence that the patient is not actively bleeding and may be evaluated by colonoscopy.

Colonoscopy

Many authors believe that colonoscopy has the highest efficacy and should be the first study in patients with major bleeding that appears self-limited.85 Whether colonoscopy should be undertaken as an ‘emergency’ depends on the patient's stability. In patients with hypotension and ongoing haemorrhage, it is difficult to safely cleanse the bowel with lavage solutions, and the continued bleeding limits intraluminal visualisation and the ability to utilise therapeutic options. In general, these patients require prompt attention with angiography or surgery.

In stable patients with self-limited haemorrhage, colonoscopy is the preferred diagnostic study. The need for bowel preparation is controversial. Colonoscopy without preparation can be described as ‘emergent’ while administering a mechanical preparation and then performing colonoscopy within 24 hours of presentation is best termed ‘urgent’ colonoscopy. The rapid time preferred for mechanical cleansing usually mandates a lavage method.

Proponents of ‘emergency colonoscopy’ have demonstrated high caecal intubation rates (95%) and a diagnostic accuracy of 72–86%.86 However, many of the reported series described atypical aetiologies for ‘massive haemorrhage’, including ischaemic colitis, inflammatory bowel disease and cancer. The usual rate of bleeding in these conditions is more amenable to urgent colonoscopy (within 24 hours) than to emergent colonoscopy. Higher bleeding rates are more common with diverticular or angiodysplastic sources.

The benefit of colonoscopy depends on its ability to provide a definitive localisation of ongoing active bleeding and the potential for therapy. Many landmarks for colonoscopy may be obscured during haemorrhage. Even when pathology is identified, establishing the presence of stigmata of recent haemorrhage is more difficult than in the upper gastrointestinal tract. In addition, colonoscopy is associated with complications such as perforation. Inconclusive findings owing to technically unsatisfactory results are frequent and failure to achieve a firm diagnosis may reflect stricter diagnostic criteria rather than inferior diagnostic skill.

Because of the inability to appreciate all intraluminal landmarks and accurately locate the segment that is bleeding, once the enodoscopist highlights a source of bleeding, the region of the intestine is best marked with a tattoo of India ink. If the haemorrhage continues and the patient fails medical management, a tattoo greatly assists the surgeon in localising the site of bleeding. The endoscopist has many therapeutic options to control the bleeding, including thermal agents (heater probes and bipolar coagulation), monopolar or bipolar diathermy, topical or intramucosal epinephrine injection and endoscopically applied clips.

Angiography

Angiography aids as a diagnostic and therapeutic option in the treatment of intestinal haemorrhage. Acute, major haemorrhage with ongoing bleeding requires emergency angiography, while patients with an early blush during nuclear scintigraphy may benefit from therapeutic angiography. Angiograms may also define a potential source for haemorrhage in occult and recurrent gastrointestinal haemorrhage. In order to appreciate an angiographic blush of contrast, the study requires a bleeding rate of at least 1–1.5 mL/min. Appropriate patient selection increases yields and avoids excessive use of angiograms. Superselective catheterisation of branch arteries and multiple injections of contrast may be required to examine the entire territory. It is important to take late films in the venous phase as they may demonstrate abnormalities that may not be seen in the arterial phase. Major complications of diagnostic arteriography include arterial thrombosis, embolisation and renal failure caused by the contrast material.

The angiographic blush may suggest a specific aetiology, but this finding lacks the accuracy of colonoscopy. Highly accurate localisation also provides for focused therapy. The haemorrhagic site may receive highly selective, intra-arterial vasopressin infusion. This medication produces potent arterial contraction that may reduce or halt the haemorrhage. Infusion rates of vasopressin begin at concentrations of 0.2 U/min and may progress to 0.4 U/min. The systemic effects and cardiac impact of vasopressin may limit maximising the dosage. Vasopressin infusion controls bleeding in as many as 91% of patients, but unfortunately bleeding may recur in up to 50% of patients once the vasopressin is reduced. However, this has been reported as allowing surgery to be performed electively in 57% of patients.87

Angiographic technology also allows for arterial embolisation to control haemorrhage. Arterial embolisation of larger vessels produces intestinal ischaemia or infarction in approximately 20% of patients. Much safer superselective mesenteric angiography using microcatheters allows embolisation of the intestinal vasa recta or vessels as small as 1 mm.

 

The high re-bleeding rate with vasopressin has led to the suggestion that other, more definitive therapeutic manoeuvres should be undertaken during angiography such as superselective embolisation, which is effective in controlling colonic haemorrhage and is associated with a low rate of post-embolisation colonic ischaemia. In a study of 27 patients, all were initially controlled with arterial embolisation although six re-bled, five of whom needed surgical intervention.88

Successful embolisation therapy provides immediate arrest of the bleeding. Embolisation agents include gelfoam pledgets, coils and polyvinyl alcohol particles. Success has been better in diverticular bleeds, which are usually fed by one vessel, than with angiodysplasias, which often have multiple feeding vessels.

CT angiography

Advanced CT angiography using thinly sliced, fast image acquisition combined with three-dimensional software packages has revolutionised the imaging of the vascular tree.89 Vessels smaller than ‘named’ vessels can be visualised, and use of CT angiography has been reported in chronic conditions such as mesenteric ischaemia and inflammatory bowel disease. Case reports and animal modelling suggest feasibility for gastrointestinal haemorrhage. The sensitivity and specificity of CT angiography in patients with gastrointestinal haemorrhage are unknown and require further research.

Surgical Management

Patients require surgical intervention if they continue to bleed profusely and medical, endoscopic and angiographic interventions have failed. Most sources of bleeding spontaneously resolve or are controlled with the therapeutic interventions described previously. Surgical therapy for intestinal bleeding is required infrequently and associated with significant mortality. Patients that are haemodynamically unresponsive to the initial resuscitation obviously require emergency surgery. In other patients the site of haemorrhage may be localised, yet the available therapeutic interventions fail to control the bleeding. Patient mortality increases with transfusion requirements. It has been reported that there is a reduced mortality (7%) for patients requiring less than 10 units of blood, while the mortality increases to 27% for patients receiving in excess of 10 units.90 Therefore, patients with ongoing haemorrhage who require more than 6–7units of blood during the resuscitation should undergo surgical intervention.

Surgeons should tailor their operative approach based on the preoperative diagnostic evaluations. Surgery starts with a thorough examination of the entire intestine through a large midline open laparotomy incision. The first objective is location of intraluminal blood with the hope of segmentally isolating a possible source of bleeding.

If no source appears obvious after the exploration phase, the surgeon may consider intestinal enteroscopy. The enteroscope or colonoscope exposes the luminal surface and transilluminates the intestinal wall. Transillumination may identify vascular anomalies, small ulcers or tumours. Endoscopic access to the intestine may require a transoral, transgastric, transcolonic or transanal approach, or a combination of these. Intraoperative endoscopy is, however, a technically difficult endeavour. A team approach with two surgeons or the availability of an experienced endoscopist is important in order to identify the elusive lesions causing the haemorrhage.

Once the haemorrhage site is identified, an appropriate segmental resection can be performed. If no source of bleeding is confirmed, but appears to arise from the colon, the surgeon should perform a subtotal or total colectomy. Stable patients will tolerate a primary ileosigmoid or ileorectal anastomosis, while unstable patients are best served with an end ileostomy with closure of the rectal stump or a sigmoid mucous fistula.

Critical issues with operative management include delaying surgery until the haemorrhage reaches a critical point beyond 10 units of blood, with an associated mortality rate between 10% and 35%, and recurrence bleeding rates of 10% due to imprecise localisation of the bleeding.91 Recurrence rates are higher (e.g. 20%) if a limited right or left colectomy is performed without precise localisation of the haemorrhage.92 A total colectomy offers the same mortality but with a lower chance of recurrent or persistent bleeding. Therefore, a total colectomy is the preferred option if preoperative localisation is not possible, or a definite site of bleeding cannot be found at laparotomy.

 

Key points

  • There has been a recent swing towards greater emphasis on preoperative investigations, especially CT, and daytime operating by specialist consultant surgeons for most urgent surgery. In cases of colonic emergencies where there is faecal contamination of the peritoneal cavity, emergency surgery may still be life-saving.

Ischaemia

  • Mild cases are treated with bowel rest and optimisation of cardiovascular status. Severe cases usually require resection.

Colonic obstruction

  • Volvulus.Emergency decompression using a proctoscope, a long soft tube such as a chest drain, or a colonoscope should, in most cases, be followed by elective definitive surgery.
  • Acute colonic pseudo-obstruction.Some patients can be managed conservatively, employing regular review and frequent plain abdominal radiographs to check caecal diameter. As caecal diameter increases, decompression is required. Many patients will respond to a trial of neostigmine. If this treatment is not successful, the colon can be decompressed with the colonoscope. Failure may necessitate caecostomy or resection. If perforation or necrosis is suspected, a full laparotomy is necessary.
  • Malignant disease.Right hemicolectomy with primary anastomosis is the treatment of choice for most patients with right-sided or transverse colonic obstruction. A subtotal colectomy may be the preferred option for patients who have a lesion at the splenic flexure. Most other patients who have an obstructing carcinoma in the left colon will be best treated by segmental colectomy with primary anastomosis where possible. Patients who are thought to be particularly at risk from lengthy emergency operations are best served by either segmental resection or colostomy.

Inflammation and/or infection

  • Diverticulits.CT is now the investigation of choice for those patients presenting as emergencies. Abscesses can then be drained percutaneously and perforations requiring surgery diagnosed early. One-stage surgery is ideal; however, in left-sided disease this is not appropriate for the unstable patient or in those with gross faecal contamination.
  • Typhlitis.There should be a high index of suspicion for this condition in the neutropenic patient. The majority respond to conservative measures including antibiotics and complete bowel rest, but perforation should be actively excluded along the course of the disease, preferably with CT.

Perforation

  • Stercoral perforation.This rare condition may be difficult to diagnose preoperatively. Awareness of the possibility of postoperative re-perforation, especially where limited resections have been performed, may be the key to a successful outcome.
  • Anastomotic leak.Postoperative assessment of the abdomen is complex, with many signs being attributable to the surgery itself. In equivocal cases, further investigations should be instigated where there is uncertainty. Active observation should be employed by senior surgical staff. In some instances, transfer to a specialist colorectal unit needs to be considered after initial resuscitation and assessment.
  • Colonoscopic damage.Signs and symptoms of perforation are not always obvious at the time of colonoscopy. A high index of suspicion, especially following interventional procedures, may allow conservative management or primary repair if surgery is performed early.

Haemorrhage

  • The majority of colonic bleeding settles spontaneously, allowing subsequent investigation to take place ‘electively’. However, ongoing bleeding should be investigated by CT angiography and then selective angiography, with or without embolisation. Surgery may be required and unless an obvious cause has been identified, subtotal colectomy with stoma formation is probably the safest procedure.

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