Acute conditions of the small bowel and appendix
Acute disease of the small bowel, from which appendicitis is considered separately, contributes substantially to the workload of the general surgeon and often patients will present as emergencies. There are many causes of acute small-bowel disease and disease in any intra-abdominal organ or the peritoneum may involve the small bowel secondarily. The pattern of acute small-bowel disease varies with the age of the patient: some conditions are more common in young people, others in an older population. The incidence of acute surgical small-bowel pathology is difficult to estimate but is probably second to appendicitis as the site of disease requiring urgent surgical intervention. Acute small-bowel disease manifests itself in one of three main ways: (i) obstruction, (ii) peritonitis and (iii) haemorrhage. These categories are not mutually exclusive and more than one type of process may exist in each clinical episode. Treatment of small-bowel disease may be operative or conservative, and the timing of surgical intervention requires as much consideration as the causes and specific treatment of small-bowel disease.
Although there are many causes of small-bowel obstruction (Box 9.1), the commonest cause in the developed world is adhesions secondary to previous surgery (approximately 60% of episodes), followed by malignancy. By comparison, in the developing world the most common cause is hernia. A large retrospective study using Scottish National Health Service data estimated that 5.7% of all hospital admissions following abdominal and pelvic surgery over a 10-year period were directly related to adhesions.1 In order to avoid unnecessary surgery and to ensure the correct surgical approach is employed, an attempt should be made to diagnose the cause of the obstruction preoperatively where possible, or at least to eliminate conditions that might require special treatment. In practice, however, the cause of the obstruction is often diagnosed at operation. A retrospective study of 102 patients undergoing surgery for adhesive small-bowel obstruction carried out between 1987 and 1992, and followed up for 14 years, reported that a total of 273 further episodes of obstruction occurred, requiring 237 hospital admissions.2 Nearly half of these further episodes resulted in more surgery.
Box 9.1 Causes of small-bowel obstruction
Within the lumen
Parasites (e.g. Ascaris)
Within the wall
Carcinoma of caecum
Potassium chloride stricture
Vascultides (e.g. scleroderma)
Outside the wall
Chemical (e.g. starch, talc)
Pharmacological (e.g. practolol)
Congenital (e.g. diaphragmatic)
Acquired (e.g. inguinal, femoral, etc.)
Internal postoperative hernia (e.g. lateral space, mesenteric defect)
The small bowel responds to obstruction by the onset of vigorous peristalsis. This produces colicky pain, usually in the central abdomen, as the small bowel is of midgut embryological origin. As the obstruction develops, the proximal intestine dilates and fills with fluid, producing systemic hypovolaemia. Further fluid is lost through vomiting, which occurs early if the obstruction is proximal. As the process continues the risk of complications increases and if the blood supply is compromised, infarction and perforation will occur. If the blood supply remains intact and the bowel is readily decompressed by vomiting and subsequent nasogastric drainage, peristalsis will eventually stop, leaving grossly dilated, non-functioning bowel. In the former scenario the pain, initially colicky, will become continuous, whereas in the latter even the colicky pain may cease as peristalsis stops.
The typical clinical presentation of small-bowel obstruction is central abdominal colicky pain, vomiting (often bile stained), abdominal distension and a reduction or absence of flatus. Vomiting may be less of a feature and a greater degree of abdominal distension observed if the blockage is in the distal ileum – in which case the vomiting often becomes ‘faeculant’ as the stagnant small-bowel contents become degraded by bacterial colonisation. Bowel sounds increase and may be audible to the patient. Localised peritonitic pain and tenderness may develop and this suggests incipient strangulation. In some patients there may be an obvious causative feature such as an irreducible hernia. The presence of surgical scars is important, as is any history of previous intra-abdominal pathology.
Although small-bowel obstruction can occur without the development of abdominal pain, the absence of this symptom should be viewed with caution. This is particularly the case in postoperative patients, where small-bowel obstruction and intestinal ileus can be difficult to differentiate. The history and examination of the patient should be sufficiently detailed to allow a diagnosis of small-bowel obstruction and to determine possible causes. Complicated small-bowel obstruction, with ischaemia or perforation, should be readily detectable by marked abdominal tenderness. It is essential to assess the patient's general state, particularly the degree of dehydration and its effect on the patient, so that adequate resuscitation is undertaken prior to any planned surgical treatment.
The aim of management is to adequately resuscitate patients, confirm the diagnosis and to identify possible bowel strangulation before gangrene and perforation occurs, so that early surgery can be arranged. There is less urgency in the recognition of non-strangulating obstruction, and a period of decompression and intravenous fluid resuscitation may allow resolution to occur without surgery. However, failure of the obstruction to resolve after 48–72 hours is usually an indication for surgical intervention.
The first step in management is fluid resuscitation and patients often require several litres of normal saline with potassium supplementation or Hartmann's solution in the first few hours after admission. Patients with a long history are likely to be severely dehydrated, with an alkalosis and associated hypokalaemia, the former due to loss of hydrogen ions in the vomit and the latter from renal compensation. Urinary catheterisation is essential to monitor response to resuscitation and measurement of central venous pressure can be helpful in the elderly, particularly those patients with coexisting morbidity. Adequate fluid replacement should be given before any surgical intervention is planned and can be given rapidly if required, even in the elderly, provided appropriate monitoring is used (see also Chapter 16).
Decompression of the stomach with a nasogastric tube will reduce vomiting in most patients, help to decompress the bowel and reduce the risk of airway contamination from aspiration. Fluid lost from the nasogastric tube should be replaced with additional intravenous crystalloids (normal saline or Hartmann's solution) and potassium supplements. Analgesia should be given early and in adequate doses, with opiates the most commonly used. This will not mask signs of peritonitis and there is no justification for withholding adequate analgesia while waiting for further clinical assessment3 (see also Chapter 5). However, the analgesia requirement should be reviewed regularly, especially in the early stages of management, as a persistent requirement for increasing amounts of opiate analgesia is a strong sign that underlying strangulation is a possibility and surgery indicated. Again, as in all emergency patients, antithromboembolic prophylaxis should be commenced early and continued until resolution (see Chapter 14).
The investigations undertaken in patients with small-bowel obstruction are aimed at:
Radiological investigations are discussed in detail in Chapter 5. Contrast-enhanced computed tomography (CT; Fig. 9.1) is increasingly used in the early assessment of patients with small-bowel obstruction, both to identify the underlying cause (particularly malignancy) and to identify features of possible strangulation. CT features of intraperitoneal free fluid, mesenteric oedema and lack of the ‘small-bowel faeces sign’, in combination with a history of vomiting, have been reported to be highly predictive of requiring operative intervention.4There is also evidence to support the role of oral contrast studies, with the passage of contrast to the colon at 4 hours being a good predictor that obstruction will resolve with non-operative treatment.5 The current view is that, although these tests may aid management, identifying patients with possible strangulation remains difficult, and the surgeon must base much of the decision-making on clinical assessment.
FIGURE 9.1 Multislice CT scan with intravenous contrast demonstrating small-bowel obstruction. With thanks to Dr Dilip Patel, Consultant Radiologist, Royal Infirmary, Edinburgh.
Intravenous fluids and nasogastric aspiration are the two components of the ‘drip and suck’ regimen, which is the first-line treatment for most patients with obstruction, particularly when the underlying cause is thought to be adhesions, as spontaneous resolution will occur in the majority. As mentioned earlier, this treatment plan should be abandoned at the first suggestion of underlying strangulation. Although non-operative management can be continued for several days in the absence of any suggestion of strangulation, surgical exploration is generally indicated if the obstruction fails to resolve after 48–72 hours. In some patients with known extensive adhesions from multiple previous explorations, it might be worth waiting longer and if so attention should be paid to nutritional support, sometimes necessitating insertion of a central line for parenteral feeding (see Chapter 17).
In the absence of clinical or CT signs (free fluid, mesenteric oedema, small-bowel faeces sign, devascularised bowel) of strangulation, or patients with partial obstruction, initial non-operative management is appropriate. These patients are good candidates for a trial of water-soluble contrast medium with both diagnostic and therapeutic purposes. The appearance of water-soluble contrast in the colon on X-ray within 24 hours from administration predicts resolution. In the absence of signs of strangulation or peritonitis non-operative treatment can be prolonged up to 72 hours (Bologna Guidelines for Diagnosis and Management of Adhesive Small Bowel Obstruction – 2010).6
The particular circumstances of any given patient determine the need for surgical intervention, but some of the commonest features in decision-making are listed in Box 9.2.
Box 9.2 Small-bowel obstruction: indications for surgery
Absolute indication (surgery as soon as patient resuscitated)
Relative indication (surgery within 24 hours)
Palpable mass lesion
Failure to improve (continuing pain, high nasogastric aspirates)
Trial of initial conservative treatment (with further investigations)
Diagnostic doubt (possible ileus)
Once a decision to operate has been made, patients should be fully resuscitated, treatment of comorbidity optimised and the stomach emptied with a nasogastric tube. The wide range of possible surgical procedures should be explained to the patient. Prophylactic antibiotics and antithromboembolic prophylaxis (if not already started) should be administered.
Generally, a midline incision is the most flexible when the diagnosis is unknown. If the patient has a previous midline incision, this should be excised and extended cranially or caudally so that the peritoneal cavity can be entered through a ‘virgin’ area. Loops of small bowel may be densely adherent to the back of the old scar and attempts to enter the peritoneal cavity through this area can result in an inadvertent enterotomy. This is clearly best avoided, particularly if the bowel wall is grossly distended, friable and diseased.
Having entered the abdominal cavity, the first step is to identify the point at which the dilated bowel proximal to the obstruction changes to collapsed distal bowel. It is important to demonstrate that such a change is present as this confirms the diagnosis of mechanical obstruction and identifies the obstructing point. The presence of uniformly dilated small bowel, or no definite point of change in diameter of the bowel, suggests that the clinical diagnosis of mechanical obstruction may be incorrect. Dilated bowel can be decompressed, usually by milking the contents proximally and aspirating via a large-bore nasogastric tube. If the small-bowel contents will not easily pass to the stomach or the bowel is so friable that retrograde decompression might produce a tear, then a suction catheter may be inserted through a small enterotomy. Where possible this should be carried out through non-diseased bowel. Decompression is particularly useful in distal obstruction when a large number of dilated loops can be difficult to handle and make subsequent abdominal closure difficult. The fluid within the bowel makes it heavy and if it is removed from the abdominal cavity, it should be handled with care so that the mesentery is not damaged. The large surface area of dilated loops results in considerable insensible fluid loss and if it is anticipated that the viscera will lie outside the abdominal cavity for a significant length of time, it should be placed in a waterproof ‘bowel’ bag or wrapped in moist swabs.
Having identified the point of obstruction, the cause is dealt with. If it is due to adhesions, they should be divided as completely as possible. Although it is not necessary or helpful to divide every last adhesion within the abdomen (as these will inevitably re-form), enough should be divided to confirm that there remains no possible site of obstruction between the duodenojejunal (DJ) flexure and the caecum. It is essential to recognise the patient in whom the clinical diagnosis of mechanical small-bowel obstruction is incorrect, as the presence of adhesions does not in itself confirm the diagnosis.
The small bowel should be resected if it is clearly ischaemic or there is disease or narrowing in the bowel at the point of obstruction, and an anastomosis may be carried out if both ends of the bowel are healthy. If the viability of a segment of bowel is unclear then it should be wrapped in warm moist swabs for several minutes and re-examined. Where viability remains in doubt it should be resected. Even after removing the obstruction, exteriorisation of the bowel may be indicated if there is generalised disease of the bowel and when an anastomotic dehiscence might be more likely. An ileostomy may be indicated in patients with Crohn's disease as part of their long-term management, and the possibility of such a step should be recognised, considered and discussed with the patient before undertaking the laparotomy. When the viability of large sections of bowel is unclear or the patient is unstable a reasonable option is to resect clearly ischaemic bowel and return the stapled ends to within the abdomen. A planned re-look laparotomy is then performed at 24–36 hours, when either an anastomosis or exteriorisation of bowel ends can be performed, depending on the patient's condition.
There has been considerable research aimed at reducing the development of further adhesions after surgery. There is some evidence that the intraperitoneal administration of icodextrin 4% solution (ADEPT®) at the end of surgery reduces intra-abdominal adhesion formation and the risk of re-obstruction. In a randomised trial the small-bowel obstruction recurrence rate was 2% (2/91) in the icodextrin groups versus 11% (10/90) in the control group after a mean follow-up period of 41.4 months (P < 0.05). However, no difference was found in the need for laparotomy.7
Abdominal closure should be carried out using a mass closure technique. There are some patients with gross obstruction or repeated procedures in whom, even after relief of obstruction, the oedematous bowel makes closure impossible. In these patients the use of a vacuum-assisted closure dressing or prosthetic mesh to allow temporary closure, with subsequent removal and formal closure a few days later, should be considered. If at subsequent surgery it is still not possible to approximate the fascial edges, alternative techniques can be used: the mesh can be left in situ and the wound edges mobilised and closed over the top; a component separation technique can be used to allow fascial closure; or vacuum-assisted closure dressings can be continued and the abdomen managed as a laparostomy. Further discussions on abdominal sepsis and dehiscence are covered in Chapter 18.
Patients can present with an acute abdomen during radiotherapy due to radiation enteritis or with acute-on-chronic attacks many years later. Patients in the former scenario can present considerable diagnostic difficulties as they are often neutropenic or suffering other side-effects of their treatment. The possibility of a primary pathology, such as acute appendicitis, arising during the course of radiotherapy must also be borne in mind but, where possible, surgical exploration is best avoided.
A more common acute presentation is with adhesions due to previous radiotherapy and these patients normally have obstructive symptoms. Again, a non-operative management policy is the best course as laparotomy is fraught with difficulty. The adhesions are often dense and, if the small bowel is inadvertently injured, there is a significant risk that it might not heal whether it is repaired or anastomosed.
Primary tumours of the small bowel are rare but can be the cause of acute small-bowel obstruction: surgical management at laparotomy will depend on the exact nature of the disease.
A more common problem is the patient with advanced intra-abdominal malignancy, with or without a past history of surgical treatment for malignancy, who presents with bowel obstruction. If the obstruction fails to settle or rapidly recurs, there is usually time to carry out appropriate investigations to determine the extent of the disease prior to surgery. CT is important in identifying a single area of obstruction, which might be amenable to surgery, as compared to extensive intra-abdominal disease without a single point of obstruction.
Ascites can be a confusing factor in such a patient and aspiration for cytology to confirm widespread malignancy can be helpful. Clearly in the presence of advanced and disseminated malignancy laparotomy should be avoided at all costs. However, if the obstructive symptoms are difficult to manage non-operatively and the patient is otherwise in reasonable condition, a laparotomy may be useful in the short term. When surgery is necessary, the exact procedure will depend on the operative findings. The choice usually lies between resection and bypass.
It is also important to recognise that not all patients have obstruction due to their malignant process. One study of patients who presented with obstruction following previous treatment of intra-abdominal malignancy reported that in around one-third of such patients the obstruction was due to a cause other than secondary malignancy.8 In a study from Japan of 85 patients who had previously undergone surgery for gastric cancer and who were subsequently re-admitted to hospital with intestinal obstruction, the cause was benign adhesions in 20%.9
The results of bypass entero-enterostomy for malignant adhesions are generally poor, with short periods of patient survival. For this reason there is growing expertise among palliative care physicians in the medical management of intestinal obstruction.10 The principles involve the use of fluid diet, steroids and octreotide. The results of such management are variable but it does offer the opportunity to spare a patient the morbidity of laparotomy in the terminal phase of their disease.
Abdominal wall hernia
Any hernia can present with intestinal obstruction (Figs 9.2 and 9.3) and if presentation is delayed, gangrene may have occurred and a bowel resection may be necessary. A Richter hernia involves part of the circumference of the bowel wall and the lumen is not obstructed. Infarction of the trapped bowel wall segment can still occur and there will be exquisite localised tenderness over a potential hernia site; the indication for surgical intervention is usually clinically apparent.
FIGURE 9.2 Supine abdominal radiograph demonstrating small-bowel obstruction in a patient with an irreducible femoral hernia.
FIGURE 9.3 Multislice CT image with intravenous contrast demonstrating small-bowel obstruction secondary to a left-sided Spigelian hernia.
Any patient with acute symptoms of a hernia that is irreducible should have urgent surgery, with repair carried out in the usual way. In the presence of obstruction necessitating bowel resection, it is probably best to avoid the use of a prosthetic mesh if possible. When there has been gross contamination of the surrounding area, the risk of complications is increased and a full treatment course of antibiotics should be given. In most cases, a direct approach to the hernia is appropriate. For a strangulated femoral hernia a ‘high’ McEvedy approach usually provides optimum access for both hernia repair and bowel resection if required. The incarcerated tissue may reduce under anaesthesia and it is unlikely, should this occur, that there will have been strangulation. However, the bowel loops must be inspected from within the hernia sac to ensure that a gangrenous loop of bowel or a strictured segment has not dropped back into the abdominal cavity (see also Chapter 4).
A final consideration is the patient who has an asymptomatic hernia who develops acute intestinal obstruction and who then demonstrates signs of an apparently irreducible swelling in the site of the hernia. The intestinal obstruction raises intra-abdominal pressure and this will, in turn, produce the irreducible hernia. The unwary may find the hernia difficult to reduce and, in their efforts to do so, can elicit tenderness. It is worth obtaining a plain abdominal radiograph in all patients with an irreducible hernia and apparent bowel obstruction. The absence of dilated small-bowel loops, or the presence of a dilated colon, should suggest the possibility that the apparently ‘incarcerated’ hernia is a secondary effect of some other intra-abdominal pathology. If in doubt, a CT scan may help reach the correct diagnosis preoperatively and allow planning of surgery. In such cases consideration will need to be given for a formal laparotomy rather than a local approach over the hernia.
Enterolith obstruction is rare: the commonest types are gallstone ileus and bezoars.
Gallstone ileus typically occurs in the elderly female and is due to the development of a cholecystoduodenal fistula after an episode of acute cholecystitis with ongoing chronic inflammation. The gallstone may be visible on a plain abdominal radiograph and gas can often be seen within the biliary tree. At surgery the stone should be removed via a proximal enterotomy and the intestine proximal to the obstruction carefully palpated to exclude the presence of a second stone. In these circumstances the gallbladder should be left alone, as cholecystectomy can be difficult and is usually unnecessary.
Bezoars may arise in psychiatric patients, the normal population after over-indulging in particular types of food (e.g. oranges and peanuts), and those who have ingested a foreign body. Rarely, they can occur with material that is collected within a jejunal diverticulum.
In children, acute presentation is usually to the paediatric department and the main differential diagnosis is gastrointestinal (GI) infection. This is discussed in more detail in Chapter 12. Intussusception in adults is usually caused by tumours of the bowel, often metastatic deposits, which should be treated on their merits once detected at laparotomy.
Connective tissue disorders
There are several systemic connective tissue disorders that can affect the GI tract and result in a loss of peristaltic power. These patients generally present with chronic symptoms and the presence of the underlying disorder is established. Occasionally, symptoms suggesting acute GI obstruction are present and the differentiation between full mechanical obstruction and ileus can be difficult. Expectant management of these patients should be pursued whenever possible. The obstructed episode may progress to perforation of the bowel and if peritonitis is present, the perforated bowel should be resected and consideration given to bringing the proximal bowel out as an ileostomy, depending on the site and state of disease. In addition, postoperative ileus is common and the differentiation of a further episode of mechanical obstruction or continuing ileus presents a diagnostic challenge.
Intestinal obstruction in the early postoperative period
GI ileus can occur after any abdominal operation. The surgeon may also be asked to see patients who have undergone gynaecological, orthopaedic or cardiac procedures who have apparent bowel obstruction. Each case must be judged on its merits but the differentiation between true mechanical obstruction and paralytic ileus can be difficult. In patients who genuinely have a mechanical obstruction, appropriate surgical intervention is frequently delayed as a result of this diagnostic dilemma. In these patients, the use of water-soluble contrast small-bowel studies and contrast-enhanced CT is often helpful and should be considered early.11
Following the development of laparoscopic surgery, there have been reports regarding the use of laparoscopic surgery in the treatment of small-bowel obstruction.12,13 Open surgery is the preferred method for surgical treatment of strangulating small-bowel obstruction as well as after failed non-operative management. However, in selected patients and with appropriate surgical skills, a laparoscopic approach can be attempted using an open access technique. Laparoscopic adhesiolysis may be suitable during a first episode of small-bowel obstruction, particularly when there has been limited previous surgery and/or a single band is anticipated, such as might occur in a patient who has previously had an appendicectomy but no other major abdominal surgery (Fig. 9.4). A low threshold for open conversion should be maintained.6,12
FIGURE 9.4 Laparoscopic view of a band adhesion. With thanks to Luigi Sussman, Auckland, New Zealand.
Small-bowel pathology may present as an acute abdomen, with either localised or generalised peritonitis. This may represent the end-stage of any condition causing obstruction, but this section considers conditions that present with primarily inflammatory signs.
Crohn's disease is a chronic relapsing inflammatory disease that can affect any part of the GI tract. A common presentation is inflammation of the terminal ileum and this occasionally presents as an acute abdomen. The small bowel alone is affected in approximately 30% of patients and the small bowel and colon together in 50%. The incidence of Crohn's disease is highest in the USA, the UK and Scandinavia and is rare in Asia and Africa, suggesting that dietary factors may be important. Similar to appendicitis, the disease can appear at any age but is most frequent in young adults and there may be a familial tendency. It is thought that the disease is most likely due to an immunological disorder, although the exact mechanism remains unclear although the final pathway is probably a microvasculitis in the bowel wall. Where possible, the management of patients with Crohn's disease should be undertaken by a surgeon with a special interest in this condition and the reader is referred to the much more detailed account of this disease in the Colorectal Surgery volume of the Companion to Specialist Surgical Practice series.14 Only first principles for managing an acute episode are discussed in this chapter.
An acute clinical episode typically presents with abdominal pain, diarrhoea and fever, and can occur in a patient who has previously been entirely well. An acute presentation is more likely in young adults, hence the differential diagnosis of Crohn's disease in patients with suspected appendicitis.
Two other clinical presentations occur, although they are less likely to be acute. First, resolving Crohn's disease will produce fibrosis in the ileum that can cause obstructive symptoms. These tend to be subacute or chronic and an acute presentation with small-bowel obstruction is rare. Second, entero-enteric or enterocutaneous fistula occurs in Crohn's disease because of the transmural inflammation that is a characteristic histological finding.
A patient who presents with right iliac fossa pain, with symptoms that are more insidious than typical appendicitis, should give rise to clinical suspicion. Inflammatory markers may be markedly elevated (white cell count, platelet count, alkaline phosphatase, erythrocyte sedimentation rate), but these are not specific to Crohn's disease. An ultrasound scan may show thickening of the bowel wall or a mass, and contrast-enhanced CT will provide more detailed information.
Surgery for acute Crohn's disease presenting de novo
If a patient with known Crohn's disease presents with an acute flare-up, or during first presentation the diagnosis of Crohn's disease is established before surgery, the patient should be referred to a surgeon with a special interest in this condition.15 However, the diagnosis may only be suspected at the time of operation, and the surgeon must proceed according to first principles. In the presence of a localised inflammatory mass or stricture, resection and primary anastomosis may be appropriate. If surgery has been carried out for suspected appendicitis and a normal appendix with ileocaecal Crohn's disease is discovered, the appendix should be removed with careful repair of the caecum, so that the possible diagnosis of acute appendicitis is ruled out of any future attacks of pain. No further action needs to be taken at this time for the Crohn's disease and appropriate investigation and treatment can be initiated in the postoperative period. Fortunately, extensive small-bowel Crohn's disease is an uncommon finding at laparotomy, but in this situation the bare minimum should be carried out. If a stricture is found it should be resected, to treat the problem and to confirm the diagnosis. If multiple strictures are found multiple stricturoplasties can be carried out, with full-thickness biopsies taken for histology. The differential diagnosis of lymphoma should also be considered.
Mesenteric ischaemia can be due to embolism or thrombosis, arterial or venous, and may be acute or chronic. Chronic mesenteric ischaemia is also termed ‘mesenteric claudication’ and is usually caused by a stenosis in the proximal part of the superior mesenteric artery. Patients develop cramp-like abdominal pains after eating, caused by the increased oxygen requirements to the small intestine, which cannot be met by increased blood flow because of the stenosis. The disease is usually associated with atherosclerosis and the investigation of choice is mesenteric angiography. This condition is discussed in more detail in the Vascular and Endovascular Surgery volume of the Companion to Specialist Surgical Practice series and is not discussed further here. These patients should be transferred to a specialist vascular surgeon.
Acute mesenteric ischaemia can affect any part of the GI tract, but is most common in the small bowel and colon. Acute ischaemia to the small bowel will usually produce infarction, whereas ischaemia to the large bowel presents with bloody diarrhoea and abdominal pain, which will usually settle over the course of a few days and is often termed ‘ischaemic colitis’. Delayed strictures may occur.
Acute small-bowel ischaemia is caused by either thrombosis or embolus. Thrombosis may occur in the superior mesenteric artery or its branches, usually associated with underlying atherosclerosis. Embolus is often associated with atrial fibrillation, when an atrial thrombus dislodges and impacts itself in the superior mesenteric artery distribution. Venous thrombosis in the distribution of the superior mesenteric vein is a less common cause of acute small-bowel ischaemia but may be related to increased blood coagulability, portal vein thrombosis, dehydration, infection, compression and vasoconstricting drugs.
Early detection of acute mesenteric ischaemia is difficult (see Chapter 5) and failure to detect this condition early continues to be one of the major causes of morbidity and mortality. The diagnosis is more common in the elderly patient who gives a history of vague but worsening abdominal pain. There may be a background history of atherosclerosis, but not invariably so. Initial examination findings can be unremarkable, lulling the clinician into a false sense of security.
The investigations for possible mesenteric ischaemia are discussed in detail in Chapter 5. CT with intravenous contrast performed as a diagnostic test for the ‘acute abdomen’ may suggest the diagnosis, but CT angiography (Fig. 9.5) is more useful if the diagnosis is suspected. Patients in whom a diagnosis is suspected should be resuscitated and prepared for laparoscopy or laparotomy. Once the diagnosis has been confirmed, a decision must be made as to whether the ischaemic bowel is salvageable by vascular reconstruction. If the underlying cause is thrombosis, then resection should be performed; however, if an embolus is present, then in selected patients exploration of the superior mesenteric artery with removal of the embolus may save an extended small-bowel resection.16 This procedure is difficult and may require associated vascular reconstruction. Advice should be sought from a specialist vascular surgeon.
FIGURE 9.5 Multislice CT image with intravenous contrast demonstrating ischaemic bowel due to superior mesenteric vein thrombosis. With thanks to Dr Dilip Patel, Consultant Radiologist, Royal Infirmary, Edinburgh.
If surgical resection is carried out, primary anastomosis may be performed, providing the blood supply to both proximal and distal margins is adequate. If embolectomy and reconstruction have been performed, or there is doubt about the margins, then anastomosis should be deferred. In this situation the distal and proximal ends of bowel should be stapled off and returned to the abdomen, with re-exploration planned within 48 hours. At re-operation an anastomosis may be performed or the ends brought out as stomas if anastomosis is contraindicated. Attention must be given in the postoperative period to the general condition of the patient in order that any possible secondary ischaemic event can be detected early.
Unfortunately, for the majority of patients with mesenteric ischaemia the small intestine is beyond salvage at the time of laparotomy and requires resection. If the whole of the superior mesenteric artery has been affected, the majority of the small bowel and part of the proximal colon will often be involved and no resection should be performed. These patients should receive intravenous opiates and be kept well sedated, as death will occur shortly afterwards.
Overall prognosis is better following acute mesenteric venous infarction as compared to acute mesenteric arterial ischaemia, and survival better following arterial embolism as compared to arterial thrombosis.17
Meckel's diverticulum is a remnant of the omphalomesenteric or vitelline duct. It arises from the antimesenteric border of the distal ileum approximately 60 cm from the iliocaecal valve. It may contain ectopic tissue, usually gastric, and is estimated to be present in approximately 2% of the population. Meckel's diverticulum may remain asymptomatic throughout life, particularly if it has a broad base and does not contain ectopic gastric mucosa. Occasionally, a band may exist between Meckel's diverticulum and the umbilicus, which can cause small-bowel obstruction. This should be treated as for a congenital band adhesion, although resection of the diverticulum should accompany division of the band. Occasionally, the diverticulum may intussuscept, also causing obstruction. Again, this will require reduction and excision. The other two common complications of Meckel's diverticulum are inflammation, when the patient presents with signs and symptoms similar to acute appendicitis, and haemorrhage. Acute inflammation is rarely suspected before surgery and the patient is usually diagnosed on the operating table (Fig. 9.6a) once a normal appendix has been found through a right iliac fossa incision or at laparoscopy. In the presence of inflammation, a Meckel's diverticulum should be excised and the small bowel repaired (Fig. 9.6b). Occult GI bleeding may occur from a Meckel's diverticulum that contains ectopic gastric mucosa and the diagnosis is usually established by CT angiogram. The treatment is again surgical resection.
FIGURE 9.6 (a) Acutely inflamed Meckel's diverticulum identified at laparotomy. (b) Operative view after resection of the Meckel diverticulum shown in (a).
Disease of the small intestine is an occasional cause of acute GI haemorrhage.18 There are no specific clinical features that distinguish the small bowel as the source rather than the colon, except that the blood loss may be less ‘fresh’ and more like melaena. As discussed in Chapter 7, it is important to exclude bleeding from a gastroduodenal source at an early stage by upper GI endoscopy. The most commonly encountered causes are vascular malformation, jejunal diverticulae, peptic ulceration in a Meckel's diverticulum, and small-bowel tumour. These are all treated by resection.
It is important to try to identify the site of bleeding before surgery, as one of the major problems at operation is that a vascular abnormality may produce no external signs. The mobility and variable anatomical layout of the small bowel mean that it can even be difficult to identify a bleeding point that has been demonstrated by imaging. CT angiography is recommended (Fig. 9.7a),18 and if a bleeding point is found, formal angiography may allow a catheter to be passed into the mesenteric branches as close as possible to the bleeding point and left in position to aid surgical localisation (Fig. 9.7b). In selected patients, the vessel may be embolised and then at surgery the ischaemic segment can be resected. If this has not been possible, intraoperative enteroscopy may be helpful. Occasionally, the only option is to place segmental soft bowel clamps throughout the small intestine, resecting the segment that fills up with blood after a period of waiting. Blind resection is often unrewarding and the risks of re-bleeding are high. If no bleeding point can be identified, the surgeon can either close the abdomen and await events, hoping that further bleeding does not occur (and this can often be the case), or divide the small bowel around its midpoint, bringing out two stomas. Subsequent bleeding can then be identified to one or other side and enteroscopy used to localise it further.
FIGURE 9.7 (a) CT angiogram with intravenous contrast demonstrating a bleeding point in the jejunum. (b) Mesenteric angiogram demonstrating embolisation of the bleeding point shown in (a). With thanks to Dr Jim Gordon-Smith, Consultant Radiologist, Royal Infirmary, Edinburgh.
Acute appendicitis is the most common intra-abdominal surgical emergency that requires operation, with an incidence of 7–12% in the population of USA and Europe. Although frequently described as a childhood illness, the peak incidence is towards 30 years of age. It is slightly more common in males (1.3–1.6:1) but the operation of appendicectomy is more common in women because of other mimicking conditions. The reader is referred to Chapter 5 for description of some of the general features and investigation of patients with acute abdominal pain, many of which relate directly to acute appendicitis.
The aetiology of acute appendicitis is bacterial infection secondary to blockage of the lumen by faecoliths, parasitic worms, tumours of caecum or the appendix, or enlargement of lymphoid aggregates within the appendix wall. In many cases, the cause of the obstruction remains unknown. There is little seasonal variation but there may be a familial tendency. The incidence has been falling since the 1930s, presumably because of improved living standards and general hygiene. Changes in dietary habits, such as an increase in dietary fibre, may also be a factor as appendicitis is less common in countries with a high roughage diet (e.g. central Africa).
The pathology of acute appendicitis is classically described as suppurative, gangrenous or perforated. Typically, there is full-thickness inflammation of the appendix wall. As the disease progresses, adjacent tissues, particularly the omentum, may also become inflamed. Haemorrhagic ulceration and necrosis in the wall indicate gangrenous appendicitis, and subsequent perforation may be associated with a localised periappendiceal mass/abscess or generalised peritonitis.
The presentation of acute appendicitis varies widely but the classical history is of central abdominal pain over 12–24 hours migrating to the right iliac fossa. Nausea and vomiting frequently occur and although diarrhoea is less common, when present it can be confused with gastroenteritis. On examination, the patient usually exhibits a low-grade pyrexia and localised peritonism in the right lower quadrant.
Appendicitis can occur at any age; although the main peak is in young adults, there is a second peak around the seventh decade. The condition is most difficult to diagnose at the extremes of age: in the very young because of the lack of history and frequent late presentation, and in the elderly because of a wide list of differential diagnoses and often less impressive physical signs.
A further factor that may produce atypical signs is the variation in the position of the appendix. A retrocaecal appendix can give rise to tenderness in the right loin and/or right upper quadrant, whereas a pelvic appendix may be associated with very little abdominal discomfort but marked tenderness on rectal examination and a history of diarrhoea. Rectal examination tends to be of little value in the diagnosis of acute appendicitis unless the organ lies in the pelvis. If the diagnosis has been established from abdominal examination, rectal examination contributes very little additional information.19
Acute appendicitis is one of a dwindling number of conditions in which a decision to operate may be based solely on clinical findings. In this context, the description of classic history and/or the presence of localised peritonism are highly predictive of acute appendicitis. The risk of morbidity and mortality is significantly increased if the appendix perforates; thus, to err on the side of overdiagnosing acute appendicitis remains accepted best surgical practice. As discussed in Chapter 5, if in doubt, laparoscopy offers an alternative to what may turn out to be an unnecessary laparotomy.
The majority of these investigations are discussed at length in Chapter 5.
Urinalysis is essential, particularly in women. Although pus cells and microscopic haematuria can occur in appendicitis, their absence may be useful in excluding significant urinary tract disease. The presence of organisms on microscopy may confirm the diagnosis of urinary tract infection. Pyelonephritis or pyonephrosis may be difficult to differentiate clinically from an acutely inflamed retrocaecal appendix. In such cases urgent investigation of the urinary tract is indicated to exclude these diagnoses prior to appendicectomy. Ultrasound is often used to identify gynaecological causes of pain and may visualise an inflamed appendix (Fig. 9.8), but cannot reliably be used to exclude appendicitis.
FIGURE 9.8 Ultrasound scan demonstrating an acutely inflamed appendix.
There has been an increasing trend towards using CT (Fig. 9.9) in the assessment of patients with acute lower abdominal pain, since the potential role of CT in acute appendicitis was first reported.20 A recent meta-analysis concluded that CT has reduced negative appendicectomy rates, and even proposed the routine use of CT in adult patients with suspected appendicitis.21 At present, due to the radiation involved, it is reasonable to proceed directly to laparoscopy for young, fit patients with a high clinical suspicion of appendicitis. As discussed in Chapter 5, ultrasonography can also be helpful. However, there should be a low threshold for CT imaging when there is diagnostic doubt, particularly in older patients, and for those in whom the risks of laparoscopy are increased, due to comorbidities, previous abdominal surgery or morbid obesity.
FIGURE 9.9 Multislice CT image with intravenous contrast demonstrating an acutely inflamed appendix.
Just as appendicitis should be considered in any patient with abdominal pain, many other abdominal emergencies must be considered in the differential diagnosis of acute appendicitis. Some of the more common conditions that present in a similar fashion include gastroenteritis, mesenteric lymphadenitis, gynaecological diseases, right-sided urinary tract disease and disease of the distal small bowel. Gynaecological disorders are probably the most important group because the removal of a normal appendix is highest in young women. Acute salpingitis, Mittelschmerz pain and complications of ovarian cyst may all be difficult to differentiate. Torsion of an ovarian cyst usually presents with a notable acute onset of pain and may sometimes be distinguished on clinical grounds. It is important to recognise ruptured ectopic pregnancy, and females of childbearing age should routinely have a pregnancy test (although it must be remembered that appendicitis is not uncommon in the first trimester of pregnancy).
The continuing development of imaging techniques and laparoscopic surgery has prompted the view that the previous proportion of normal appendices removed in the ‘open surgery’ era (typically up to 20% of patients operated on) was unacceptably high. Although it is clearly advantageous to spare patients unnecessary surgery, the morbidity and mortality of failing to diagnose appendicitis until perforation has occurred is greater than that associated with the removal of a normal appendix. If the diagnostic tools discussed in Chapter 5 are not readily available, the best policy remains early surgery when there is clinical suspicion of acute appendicitis.
A positive diagnosis of acute appendicitis requires urgent surgery as any further delay will result in a higher proportion of perforation.22,23 Where the diagnosis is in doubt, in patients who are systemically well and/or have mild signs, early exploration in the middle of the night is not indicated and these patients can be safely observed with regular review or investigations as described in Chapter 5. The incidence of perforation in this subgroup of patients is no higher than if they are taken to theatre for early exploration.24,25 Intravenous antibiotics may be given once a decision has been made to operate or to actively treat acute appendicitis non-operatively.
Conventional Appendicectomy: A classical appendicectomy incision is made over the point of maximum tenderness and this usually lies on a line between the anterior superior iliac spine and umbilicus in the right iliac fossa (McBurny's point). The skin incision should be horizontal and placed in a skin crease if possible to achieve a satisfactory cosmetic result. The abdominal wall muscles may be separated in the traditional ‘muscle splitting’ fashion or the abdominal cavity may be entered at the lateral margin of the rectus muscle, with retraction of the muscle fibres medially.
Once the abdominal cavity has been entered, the appendix should be located by gentle palpation and it may be most easily mobilised from the inflammatory adhesions by finger dissection. If it is obviously inflamed, it should be removed, lavage performed and no further laparotomy carried out. If the appendix is macroscopically normal, examination should be undertaken of the terminal ileum (for at least 60 cm to exclude an inflamed Meckel's diverticulum) and small-bowel mesentery and pelvis, both by palpation and direct visualisation. Any free peritoneal fluid should be examined and cultured. The presence of bile staining indicates bowel perforation at some point, such as perforated peptic ulcer, and faecal fluid indicates colonic perforation. In both cases a full laparotomy is indicated. In the former situation, it is best to close the right iliac fossa incision in preference to an upper midline, but in the latter condition some surgeons advocate extending the right iliac fossa incision across to the left as a muscle-cutting lower abdominal transverse incision. If in doubt, a midline incision is best.
It used to be traditional teaching to bury the appendix stump but there is now general recognition that simple ligation of the stump is adequate.26 If the appendix has perforated at the base, formal repair of the caecal pole is advised. Leaving an excessively long stump should be avoided as this can become ischaemic and produce symptoms postoperatively. Peritoneal lavage should always be carried out but surgical drains are unnecessary unless there is an established abscess cavity.
All patients should receive prophylactic broad-spectrum antibiotics against the risk of wound infection, which is the commonest complication of appendicectomy.27,28 A single dose is as effective as three doses for wound prophylaxis. For perforated appendicitis, a 5-day treatment course of antibiotics is used by many surgeons, although there are limited data to support this view. When patients can tolerate diet, completing the course of antibiotics orally has been shown to reduce hospital stay without additional complication.29 Although the risk of deep vein thrombosis is relatively low in young patients, prophylaxis is best administered as a routine as not all patients will make a swift recovery and early postoperative mobilisation may be delayed.
Prophylactic antibiotics should be administered in all patients undergoing appendicectomy for acute appendicitis in order to reduce the risk of wound infection.27,28
Laparoscopic Appendicectomy: The advantages of laparoscopic appendicectomy over the open approach have been extensively studied over the last 15 years, although individual studies have produced conflicting results.30–35
A recent Cochrane database systematic review of 67 studies has confirmed the benefit of the laparoscopic approach in relation to less pain, faster recovery and a lower incidence of wound infections. However, it suggests that there is an increase in intra-abdominal abscesses (odds ratio 1.87) in patients undergoing a laparoscopic procedure. A laparoscopic approach was generally recommended for patients with suspected appendicitis, especially young female, obese and working patients.36
The increase in abscesses may of course reflect problems with surgical technique or poor patient selection. There is no reason why the laparoscopic approach should have a higher complication rate, if performed correctly, and indeed it brings with it the possibility of performing a better lavage than at open surgery. The increased abscesses reported may relate to inadequate removal of the lavage fluid (see below).
As skill in laparoscopic techniques has become more widespread, laparoscopic appendicectomy has become increasingly common.37 It seems reasonable to proceed with laparoscopic appendicectomy for any patient in whom an acutely inflamed appendix is discovered during diagnostic laparoscopy, providing the surgeon has the relevant skills. Large and obese patients probably benefit more from the laparoscopic approach due to the larger wound required at open surgery.
Technique: The basic principles of laparoscopic appendicectomy mirror those of conventional open surgery. The appendix mesentery is usually divided first and may be cauterised with electrocoagulation at the level of the appendix, tied in continuity with ligatures or controlled by application of haemostatic clips. The appendix itself is usually ligated with a preformed loop ligature. An alternative, effective and rapid technique is to apply an endoscopic stapling device to the mesoappendix. The appendix can then be removed after further application of the stapler or by using a pre-tied ligature. Unfortunately, such stapling devices are expensive.
The inflamed appendix should usually be removed in a retrieval bag as it is important to remove the appendix through the abdominal wall without contaminating the soft tissues. A friable or perforated appendix should be handled gently and care taken to remove all debris, including any loose faecolith. A thorough lavage is essential in contaminated cases to prevent postoperative abscess formation. In the authors' institution it is standard practice in such cases to leave a drain in the pelvis to remove any residual lavage fluid in the immediate postoperative period (this may often be removed after 12–24 hours). In patients with generalised contamination from a perforated appendix, it must be remembered that the advantages of the laparoscopic approach are small, as even if the operation can be completed laparoscopically these patients rarely recover quickly due to the systemic nature of their disease. If conversion to open surgery is required then the laparoscope can be used to transilluminate the abdominal wall, allowing accurate placement of a conventional surgical incision, which it may be possible to keep to a smaller size than would otherwise have been used.
There have been various descriptions of operative technique for laparoscopic appendicectomy and different positions for port placement. If ports are placed low in the abdominal wall, the cosmetic result may be improved. One approach is to place working ports at the umbilicus and in the suprapubic region, with the camera port in the left iliac fossa.
One of the reported complications of laparoscopic appendicectomy is leaving too long a stump and risking recurrent symptoms.38 Care must therefore be taken to ensure that the entire appendix has been fully mobilised to avoid this complication.
The Normal Appendix At Open Surgery: In practice, if a standard incision has been made for a planned open appendicectomy, a normal appendix should probably be removed in every patient, including those with Crohn's disease that affects the caecum, in order to prevent future diagnostic dilemma. The removal of a normal appendix may still be associated with morbidity; the wound infection rate is the same as for removal of a non-perforated inflamed appendix. The main long-term complication is small-bowel obstruction. This has been examined in a historical cohort study of 245–400 patients in Sweden with population-based matched controls.39 This study calculated the cumulative risk of surgically treated small-bowel obstruction following open appendicectomy to be 1.3% after 30 years compared with 0.21% for non-operated controls. Higher risk was associated with those patients undergoing appendicectomy for other conditions, a perforated appendix and a normal appendix.
The Normal Appendix At Laparoscopy: The complication rate associated with open removal of a normal appendix is 17–21%, depending on whether other conditions have been identified.40,41 The long-term sequelae of laparoscopic removal of a normal appendix remain relatively unknown, but the rate is hopefully less. Removal of a normal appendix at diagnostic laparoscopy is not mandatory and should not usually be undertaken if a definite alternative diagnosis for the patient's symptoms, such as pelvic inflammatory disease, is established.
There is more debate about what should be done if a normal appendix is seen and no other condition can be identified to account for the patient's symptoms. In this scenario, there are two arguments in favour of removing the appendix. (i) There is a small incidence of appendicitis on histological examination of a macroscopically normal appendix.42,43 One study evaluating the ability of laparoscopy to discriminate between a normal and an inflamed appendix demonstrated a sensitivity of 92% and a specificity of 85% if an appendix with isolated mucosal inflammation was considered to be inflamed.44 (ii) Removal of the appendix prevents diagnostic dilemma in a patient who continues to suffer from abdominal symptoms and signs following laparoscopy. The counter argument is that the clinical significance of isolated mucosal inflammation in an otherwise normal appendix remains highly debatable, and that all operative interventions or procedures are associated with some form of risk.
Surgeons will have their own opinions on this matter and decisions may vary between patients and the clinical presentation. The final course of action has to be left to the operating surgeon and the patient should be counselled about the options preoperatively. In a patient who has required repeated admissions to hospital with recurring right iliac fossa pain, it would make sense to remove the appendix, even if normal, to at least exclude appendicitis from the differential diagnosis on any possible future admissions.
It has been suspected for many years that not only can acute appendicitis settle spontaneously, returning with recurrent symptoms at a later date, but that it can be successfully treated in some patients with antibiotics, providing there are no signs of overt peritonitis. The former is supported by a study which reported that 71 of 1084 patients (6.5%) who underwent appendicectomy for acute appendicitis admitted to similar symptoms 3 weeks to 12 years previously.45 The latter is supported by a number of randomised trials comparing antibiotic treatment versus appendicectomy in patients with suspected appendicitis.46–49 The difficulty with such a strategy is highlighted by one recent trial, carried out in 243 patients, which found that despite CT assessment 18% of patients were identified at surgery to have unexpected complicated appendicitis.49 Furthermore, 12% of those treated with antibiotics required appendicectomy within 30 days and a further 26% developed recurrent appendicitis requiring surgery within 1 year. A recent Cochrane review of five low to moderate quality randomised trials (901 patients) found that 73% of patients treated with antibiotics were cured (including recurrence within 1 year) within 2 weeks without major complications, compared to 97% of patients who directly underwent appendicectomy.50
It therefore follows that when a diagnosis of acute appendicitis is suspected appendicectomy should be carried out, and that surgery remains the gold standard treatment for acute appendicitis. Antibiotic treatment might be used as an alternative treatment in the absence of overt peritonitis in specific patients where there are factors that favour a non-operative approach. However, this decision must be made in the knowledge that regular review is essential, surgery is indicated if resolution does not take place within 12–24 hours or the patient deteriorates, and that there is a significant risk of recurrent symptoms during the next 12 months.
Treatment Of Atypical Presentation Of Acute Appendicitis
The natural history of acute appendicitis left untreated is that it will either resolve, become gangrenous and perforate, or become walled off by a mass of omentum and small bowel. The latter situation prevents inflammation spreading to the abdominal cavity yet resolution of the condition is delayed. Such a patient usually presents with a longer history (1 week or more) of right lower quadrant abdominal pain, appears systemically well and has a tender palpable mass in the right iliac fossa. This condition is best managed non-operatively as the risk of perforation has passed and removal of the appendix at this late stage can be difficult and is associated with a significant complication rate. A recent meta-analysis reported that the non-operative treatment of complicated appendicitis (appendix mass or abscess) is associated with a decrease in complications compared to acute appendicectomy, with a similar duration of hospital stay.51 The differential diagnosis includes Crohn's disease in younger patients and carcinoma of the caecum in older patients. Confirmation is obtained from ultrasound or CT and it is not uncommon for these investigations to reveal an underlying abscess.52 However, if the patient remains systemically well, non-operative treatment can still be pursued with percutaneous drainage of any fluid collections if required (see below). Following resolution of the symptoms and mass, further investigations, which might include CT and colonoscopy, must be used to exclude these other conditions.
In the past, routine interval appendicectomy (6 weeks to 3 months) was considered essential to prevent recurrent symptoms in the young and to exclude carcinoma in the elderly. However, providing carcinoma can be excluded by other means, routine interval appendicectomy is no longer recommended. In the majority of patients the appendix has been destroyed and in one study only 9% of patients treated non-operatively for an appendix mass subsequently developed recurrent symptoms, and all did so within 5 months.52
A systematic review has confirmed that non-operative management of an appendix mass will be successful in the majority of patients and recurrence of symptoms is low. As a result the routine use of interval appendicectomy is no longer justified.53
In some patients the appendix becomes walled off by omentum but has perforated and an abscess will develop in the periappendiceal region. This may be in the right paracolic gutter, the subcaecal area or the pelvis and can be visualised by either ultrasound (Fig. 9.10) or CT (Fig. 9.11). Unlike with a simple ‘appendix mass’, the patient is usually systemically unwell with abdominal tenderness. As for all abscesses, drainage is the best treatment, either under radiological control or surgically. There is no doubt that surgical drainage can be associated with significant complications, not least because tissues and organs adjacent to the abscess will be friable and must be handled with great care. The alternative of radiologically guided drainage (Fig. 9.12) has been reported to produce lower complications and equivalent early operation/re-operation rates.51,54,55 It would therefore seem reasonable to use the non-operative approach in any patient in whom overt signs of peritonitis are absent. If surgery is required then the residual necrotic appendix should be identified and resected along with the inevitable faecolith, which if left contributes to a protracted recovery.
FIGURE 9.10 Ultrasound scan demonstrating an appendix abscess. With thanks to Dr Paul Allan, Consultant Radiologist, Royal Infirmary, Edinburgh.
FIGURE 9.11 CT scan of the same patient as shown in Fig. 9.10, demonstrating the appendix abscess. With thanks to Dr Paul Allan, Consultant Radiologist, Royal Infirmary, Edinburgh.
FIGURE 9.12 Radiograph of the same patient as shown in Figs 9.10 and 9.11, following percutaneous drainage of the appendix abscess, with drain in situ.
As mentioned above, there is certainly a group of patients who suffer from recurrent appendicitis45 and who benefit from appendicectomy. Similarly, there are some patients who, having recovered from an acute attack of appendicitis, go on to suffer from recurrent less-acute episodes of abdominal pain. These also benefit from appendicectomy, usually as an elective procedure. Assessment in difficult cases can be helped by CT (Fig. 9.13), but for many patients laparoscopy is the best investigation, at which the appendix can be removed. A small randomised trial has reported improvement in chronic recurrent right lower quadrant pain following laparoscopic appendicectomy compared to laparoscopy alone.56
FIGURE 9.13 CT image showing an abnormal and thickened tip of appendix without contrast. These findings were confirmed at appendicectomy when a grossly abnormal distal half of appendix was found.
Appendicitis in pregnancy
The rate of appendicitis in pregnancy is similar to that in the non-pregnant female population. The preoperative diagnosis of acute appendicitis can be difficult in pregnancy, and a low threshold for surgical intervention has traditionally been recommended, as complicated appendicitis is associated with a higher rate of foetal loss and increased maternal morbidity. A recent systematic review reported a negative appendicectomy rate of 27%, higher than in the non-pregnant population, and rates of foetal loss of 3.4%, 12.1% and 7.3% in simple, complicated and negative appendicectomy, respectively.57 Recognition of the risk associated with negative appendicectomy58 has led to guidelines from the American College of Radiology recommending that ‘magnetic resonance imaging can be accurate in excluding appendicitis where the ultrasound exam does not visualise a normal appendix’. Where emergency access to such imaging is possible it is recommended, but it should not delay surgery in patients with a high clinical suspicion of appendicitis.
Many reports have demonstrated laparoscopic appendicectomy to be a safe and effective procedure during pregnancy. With modification of port position the laparoscopic approach has even been reported during the third trimester. One recent large observational study has reported a higher risk for laparoscopy, with an odds ratio of 2.3 for foetal loss compared to conventional surgery,58 and this has influenced the results of a subsequent systematic review.57 The result of this single study does not contraindicate laparoscopic appendicectomy in pregnancy, but does indicate a need for further research on the subject. Currently the Society of American Gastrointestinal and Endoscopic Surgeons continues to recommend laparoscopic appendicectomy as the treatment of choice for pregnant patients.59
The assessment and decision-making for such patients should involve both senior general and obstetric surgeons. A reasonable approach is to use laparoscopy in the first trimester or when, despite adequate imaging, the diagnosis is in doubt. In later pregnancy open surgery may be preferred when the diagnosis is confirmed but the approach will depend upon surgeon expertise. In all cases there should be a low threshold for conversion to open surgery if difficulties are encountered. If the appendix is found not to be inflamed at laparoscopy then it should not routinely be removed.
Postoperative Complications And Outcome
The duration of hospital stay depends on local resources, policies, the patient's general condition and any coexisting disease. It is now clear that laparoscopic appendicectomy is associated with a more rapid return to normal activities36 than conventional surgery, but this does not necessarily relate to a shorter hospital stay. Much will depend on local factors, and reports of routine early discharge (24–48 hours) after conventional appendicectomy60 suggest that full diet and early mobilisation are well tolerated by the majority of patients.
This is the commonest postoperative complication, occurring in around 10–15% of patients following a conventional right iliac fossa incision. In most patients there is superficial inflammation, which responds to antibiotics. In a smaller number there will be dehiscence of the wound and purulent discharge. Occasionally, surgical intervention may be required to drain a collection in the abdominal wall. The current practice of early discharge from hospital results in many wound infections developing once the patient is at home, and the possibility of this complication should always be discussed with the patient. Wound infection appears to be significantly less following laparoscopic appendicectomy.36
There is no evidence that wound infiltration with local anaesthetic is associated with any increase in the incidence of wound infection but there is also minimal benefit in reducing postoperative wound pain.61,62 After open appendicectomy the skin may be closed with interrupted stitches or a continuous suture and this does not appear to affect wound infection rates. Some surgeons leave the skin incision open if there has been gross contamination of the wound in perforated appendicitis. The subsequent cosmetic result of such a scar is usually satisfactory but healing takes several weeks.
Other septic complications
Pericaecal fluid collections are relatively common and are usually indicated by the presence of abdominal discomfort and a low-grade pyrexia. They can usually be diagnosed by ultrasound and treated by antibiotics, especially in children,63 or occasionally aspiration; formal drainage is rarely necessary. Pelvic abscess is a less common complication that presents with lower abdominal discomfort and swinging pyrexia. The symptoms may be delayed by 10 days or more and a soft tender mass may be palpable on rectal examination, although this is not always the case. Again, ultrasound and often CT is required for diagnosis and, if pus is aspirated, a percutaneous drain should be placed if possible. Occasionally, a pelvic abscess may be difficult to drain percutaneously and in this situation the options are between antibiotics, drainage of the abscess into the rectum or to proceed to surgical drainage through the abdomen. The decision is influenced by the general condition of the patient. Prolonged use of antibiotics should be avoided and further attempts made for drainage if the collection is not resolving on repeated imaging.
In patients who have undergone laparoscopic appendicectomy for perforated appendicitis, signs of generalised peritonitis can develop in the first 48 hours. This may be due to dissemination of infected fluid through the abdominal cavity, possibly by circulation of the carbon dioxide used to create the pneumoperitoneum. The main differential diagnosis in this situation is iatrogenic injury to the intestine and, if in doubt, re-laparoscopy is indicated.
The mortality of appendicitis is associated with the age of the patient and delayed diagnosis (perforated appendix). A report from the Royal College of Surgeons of England showed a mortality of 0.24% and morbidity of 7.7% in 6596 patients undergoing open appendicectomy between 1990 and 1992.64 A further prognostic consideration is the incidence of subsequent tubal infertility after appendicectomy. Although one report suggested that the increased risk of tubal infertility following perforated appendicitis was 4.8 in nulliparous women and 3.2 in multiparous women,65 a more recent historical cohort study revealed no long-term consequence on fertility.66