Organisation of emergency general surgical services and the early assessment and investigation of the acute abdomen
The management of emergency surgery has undergone huge changes over the last 5 years as both surgeons and hospital managers have finally recognised that it is not only a major part of ‘general surgery’, but also associated with a significant morbidity and mortality, accounting for a large part of hospital resources. The American College of Surgeons National Surgical Quality Improvement Project recently examined the results of emergency appendicectomy, cholecystectomy and colorectal resections in 95 hospitals between 2005 and 2008.1 They found that the risk of severe morbidity or death was 3.7% in the 30 788 appendicectomies performed, 6.37% in the 5824 cholecystectomies and 41.56% in the 8990 colorectal resections. Interestingly, they also identified that in 7–10% of hospitals good or bad performance could be generalisable across the three procedures, suggesting that there are ‘best’ and ‘worse’ practices to be identified.
Reduced bed days and improvements in patient care are, not surprisingly, associated with earlier and better clinical decision-making, prompt and appropriate surgery, along with reductions in readmissions and later requirements for surgery. Until recently, many surgical units throughout the world continued their elective work in tandem with their on-call commitments and, as a result, getting timely surgical intervention on all but the sickest emergency patients was difficult, resulting in delayed operations, usually going on late into the night and often carried out by junior surgical trainees. However, over the last few years, due to a number of factors, this has all changed. The increased number of surgical admissions to many hospitals, associated with regional reorganisation of surgical services2,3 and the associated increase in workload,4 the reduced experience of surgical trainees due to the reduction in junior doctors' hours and training period,5 and the recognition that early assessment by experienced senior surgeons with timely surgical intervention,6 preferably by someone with an interest in that condition, have led to a recognition that a radical change in the provision of acute general surgical services was required. The Association of Surgeons of Great Britain and Ireland (ASGBI) held a consensus meeting on the future of emergency general surgery in 2006, subsequently publishing their conclusions,7 which are summarised in Box 5.1. A subsequent survey of consultant surgeons in the UK by the ASGBI8 reported that: only 55% considered they were able to care well for their emergency patients; the workload was increasing with junior support decreasing; only 19% had comprehensive interventional radiology service out of hours; 55% had inadequate access to an emergency theatre; current pressure within the NHS favoured elective over emergency work; many felt they could not argue the case for change at a local level; and many felt that helpful changes would include national standards of practice and of service delivery, proper theatre access, and increased separation of elective and emergency work.
Box 5.1 Summary of the conclusions of the consensus meeting of the Association of Surgeons of Great Britain and Ireland (ASGBI) in 2006 on emergency general surgery7
Organisation of emergency general surgical services
Separation Of Elective And Emergency Surgery
Where in the past the continuity of care for surgical patients was maintained by the ‘middle grade’ surgical team, current rotas are now primarily of a shift pattern where the maximum time worked per week is around 48 hours, and as a result consultants find they rarely work with the same trainees9 and continuity of care is reduced.10 One solution to this problem was the introduction of the ‘surgeon of the day’, first suggested in 1995,11 and then fully implemented in Edinburgh, UK, as the ‘emergency team’ in 1997.12 With this system, the whole surgical team (consultant and supporting junior staff) have no elective commitments for their time on call and, although unfortunately shift working remains essential in many countries due to restricted working hours, the same trainees take part in the emergency team for extended periods of time. Their subsequent attachment to elective activity then no longer suffers from the disruption associated with on-call shifts, a state of affairs that enhances both emergency and elective training opportunities. This ‘emergency team’ system, with various adaptations according to local requirements,13 has now been adopted in many units throughout the UK and increasingly worldwide. Two recent publications from the Association of Surgeons of Great Britain and Ireland include descriptions on the different ways that individual hospitals and regions in the UK have changed their service in order to improve the provision of emergency surgical services.14,15 Box 5.2 provides recommendations published by the Royal College of Surgeons of England16 for the separation of elective and emergency general surgery.
Summary of recommendations for separation of emergency and elective surgical care
Copyright The Royal College of Surgeons of England. Reproduced with permission. Separating emergency and elective surgical care: recommendations for practice, The Royal College of Surgeons of England, 2007 (www.rcseng.ac.uk/rcseng/content/publications/docs/separating_emergency_and_elective.htm).
The emergency team undoubtedly improves the ability of the consultant general surgeon, as well as the middle grade team, to provide safe and effective emergency care, but requires other conditions to be met if this is to be both efficient and cost-effective, not only in terms of lost elective activity for the consultant but also training opportunities for the surgical trainees. These include easy access to radiological imaging, a dedicated emergency operating theatre with full (and senior) anaesthetic support available 24 hours each day,17 enough surgical admissions to make the system worthwhile, and a distinct and dedicated admission area for emergency patients to be assessed. This is particularly useful in the assessment of patients with equivocal clinical signs, such as in early appendicitis, where the value of ‘active observation’ with reassessment after 2–3 hours by the same surgeon, repeated thereafter as necessary, is well established.18
Emergency general surgery should be provided by a team that is free of elective commitments. All emergency general surgical patients should be admitted to a single dedicated admission area within the hospital, where they can be assessed and reviewed by the admitting surgical team. This should be supported by easy access to an emergency operating theatre and appropriate and timely radiological investigations.7,16
Subspecialisation In Emergency General Surgery
Along with the recognition that emergency surgery deserves more attention and support has also come the recognition that specialist conditions are often better treated by surgeons with a particular interest and experience in that subspeciality. This has of course been recognised for some time in the elective performance of a number of surgical procedures, including oesophagectomy, gastrectomy, abdominal aortic aneurysm repair, lung lobectomy, cardiac surgery and colectomy,19,20 and although mainly thought to be related to hospital and surgeon volumes,21 specialisation of the surgical team is also an important factor.22 However, there are now data available to support similar improvements in patient outcomes for emergency conditions, such as acute gallstone disease23,24 and acute colorectal disorders.25 This is not surprising considering the subspecialisation that has occurred in general surgery over the last decade,26 with consultant surgeons now being expected to deal with surgical conditions in the emergency situation that they no longer see in their elective practice. Reports of the separation of upper and lower elective and emergency gastrointestinal (GI) services in one region of Scotland have been encouraging. Not only has there been a significant increase in the number of patients with acute gallstone problems undergoing the same admission laparoscopic cholecystectomy,27 there have also been improvements in the management of perforated duodenal ulcers,28 and acute diverticulitis where patients have a lower mortality and fewer stomas.29 The challenge now is for all those surgeons involved in the development and provision of emergency surgical care to produce on-call rotas that allow, where possible, patients with specific subspeciality conditions to be treated and operated upon by surgeons with a specific interest in that area. This will undoubtedly involve reorganisation of regional emergency surgical services, bringing together a wider group of surgeons for the on-call rota, with the ability to provide both upper and lower GI cover. The political hurdles of closing some emergency services in some hospitals in order to provide these larger emergency surgical units in other hospitals must be overcome if the undoubted improvements in patient care associated with dedicated emergency surgical services delivered by surgical teams with appropriate subspeciality expertise are to be realised, while at the same time providing robust junior doctor rotas that comply with the appropriate working time directives.
Early assessment of the acute abdomen
Attempts to improve preoperative diagnosis and early management of patients with acute abdominal pain are continuingly being made; this section discusses all the current available techniques and the evidence for their incorporation into emergency surgical practice. For the purposes of most studies looking at acute abdominal pain, the broad definition is taken as ‘abdominal pain of less than 1 week's duration requiring admission to hospital, which has not been previously treated or investigated’. However, this must be accepted as a fairly loose definition.
For an emergency team system to work efficiently the surgical team must have rapid access to diagnostic blood tests and appropriate imaging, which should include plain and contrast radiology, both diagnostic and interventional (percutaneous drainage and biopsy), ultrasound (US) and computed tomography (CT). Furthermore, plain radiography evaluated by senior radiologists substantially enhances senior surgical assessment of patients with acute abdominal pain, resulting in reduced surgical admissions.30 All these modalities are discussed below.
Conditions Associated With Abdominal Pain
Many studies have looked at the spectrum of patients admitted to hospital with acute abdominal pain and the approximate percentage represented by each condition is now well understood. Figures from one study31 appear to be fairly representative (Box 5.3). In this study the 30-day mortality in 1190 emergency admissions was 4%, with a perioperative mortality of 8%. Not surprisingly, the mortality rate was age related, with perioperative mortality in patients below 60 years being 2%, rising to 12% in those 60–69 years and reaching 20% in patients over the age of 80 years. Laparotomy for irresectable disease was the most common cause of perioperative mortality (28%), with ruptured abdominal aortic aneurysm (23%), perforated peptic ulcer (16%) and colonic resections (14%) all being associated with significant perioperative mortality.
Conditions that may present with acute abdominal pain
Non-specific abdominal pain (NSAP) (35%)
Acute appendicitis (17%)
Intestinal obstruction (15%)
Urological causes (6%)
Gallstone disease (5%)
Colonic diverticular disease (4%)
Abdominal trauma (3%)
Abdominal malignancy (3%)
Perforated peptic ulcer (3%)
Conditions contributing 1% or less
Exacerbation of peptic ulcer
Ruptured abdominal aortic aneurysm
Gynaecological causes (these may go unnoticed as NSAP)
Inflammatory bowel disease
Reproduced from Irvin TT. Abdominal pain: a surgical audit of 1190 emergency admissions. Br J Surg 1989; 76:1121–5. © British Journal of Surgery Society Ltd. Reproduced with permission. Permission is granted by John Wiley & Sons Ltd on behalf of the BJSS Ltd.
What stands out from all the studies on acute abdominal pain published over the last few decades is the high incidence of non-specific abdominal pain (NSAP), with published figures of 40% or more.32 NSAP usually reflects a failure of diagnosis, as many of these patients do have a cause for the pain and it has been shown that further investigations, such as laparoscopy, can reduce the overall incidence of NSAP to around 27%.33
Some authors have examined this diagnosis of NSAP further and describe a certain number of alternative conditions that could be related (Box 5.4),32 including abdominal wall pain34and rectus nerve entrapment.35 In some cases of NSAP, detection of abdominal wall tenderness (increased abdominal pain on tensing the abdominal wall muscles) may be a useful diagnostic test.36 Possible causes of abdominal wall pain are also given in Box 5.4. The major problem with making a diagnosis of NSAP is in missing serious underlying disease, and the late Tim de Dombal demonstrated that 10% of patients over the age of 50 years who were admitted to hospital with acute abdominal pain were subsequently found to have intra-abdominal malignancy.37 Half of these patients had colonic carcinoma and the major concern was that 50% of the patients who were subsequently proved to have intra-abdominal cancer were discharged from hospital with a diagnosis of NSAP.
Box 5.4 Causes of non-specific abdominal pain32
Irritable bowel syndrome
Abdominal wall pain34
Acute gynaecological conditions such as pelvic inflammatory disease and ovarian cyst accidents are another group of diagnoses that may often be included under the umbrella of NSAP, simply because of failure to take a good history or examination or even perform a thorough pelvic examination, whether digitally, ultrasonographically or at operation. In one study from a general surgical unit, gynaecological causes represented 13% of all diagnoses in a consecutive series of all emergency admissions (both male and female) initially presumed to be ‘surgical’ in origin.38 As many of these patients present with ‘query appendicitis’, accurate assessment is essential if unnecessary operations are to be avoided, and even then the diagnosis may remain hidden unless the surgeon examines the pelvic organs once a normal appendix has been found. However, with the increased use of diagnostic laparoscopy, discussed later in this chapter, these conditions are now being recognised by the emergency surgeon with much greater frequency. Early recognition and appropriate treatment of pelvic inflammatory disease may help to avoid potentially serious long-term sequelae and must be encouraged.39 Indeed, the condition of Curtis–Fitz-Hugh syndrome, when transperitoneal spread of pelvic inflammatory disease produces right upper quadrant pain due to perihepatic adhesions, is now well recognised and care must be taken to differentiate this from acute biliary conditions.40
Although much is made of possible ‘medical’ causes of acute abdominal pain in surgical textbooks, the incidence of conditions such as myocardial infarction, lobar pneumonia and some metabolic disorders is extremely small, though many still masquerade as NSAP. However, the possibility of such conditions must still be borne in mind during the clinical assessment of all patients with acute abdominal pain: one study has shown that 19 of 1168 children (1.6%) admitted to hospital with acute abdominal pain had pneumonia as the sole cause of symptoms.41 It is therefore still extremely important to recognise these medical conditions when they do present, before exploratory surgery, as the mortality can be significantly increased.42
History And Examination (Including Computer-Aided Diagnosis)
In the early 1970s, de Dombal et al.43 in Leeds and Gunn44 in Edinburgh developed a computer program based on Bayesian reasoning that produced a list of probable diagnoses for individual patients with acute abdominal pain. They demonstrated that the accuracy of clinical diagnosis could be improved by around 20%, and a subsequent multicentre study confirmed this finding.45 Furthermore, these studies showed that there was a reduction in the unnecessary laparotomy rate and bad management errors (patients whose surgery is incorrectly delayed). When the reasons for the improvement in diagnostic accuracy associated with the use of computer-aided diagnosis (CAD) were examined, there appeared to be three main factors involved: (i) peer review and audit, which is invariably associated with improved results in most aspects of medical management;46 (ii) an educational factor related to feedback;47 and (iii) probably of greatest significance, the use of structured data sheets on to which the history and examination findings were documented before being entered into the computer program. One study went on to demonstrate that the diagnostic accuracy of junior doctors improved by nearly 20% when they used structured data sheets alone, without going on to use the CAD program.48 The same study also demonstrated that medical students assessing patients with the structured data sheets and then using the CAD program reached similar levels of diagnostic accuracy to qualified doctors. Other studies have since confirmed similar improvements in clinical decision-making following the introduction of these data sheets.49
The message from all these studies is clear: a good history and examination remain essential for both diagnostic accuracy and good clinical decision-making, and the use of a structured data sheet helps the clinician to achieve this objective.8,9,45
The aim of both the history and examination is to determine a diagnosis and clinical decision. There are undoubtedly specific features associated with all acute abdominal conditions that are well established; however, it remains the ability to identify the presence or absence of peritoneal inflammation that probably has the greatest influence on the final surgical decision. In other words, the presence or absence of guarding and rebound tenderness, and a history of pain on coughing, correlates well with the presence of peritonitis.50 The differential diagnosis of acute appendicitis from NSAP is always difficult, particularly in children, and both guarding and rebound tenderness are significantly more likely to be present in acute appendicitis.51 There was always great emphasis in the past on the importance of a rectal examination in patients with suspected acute appendicitis to elicit tenderness within the pelvis. However, when rebound tenderness is detected in the lower abdomen, as evident by pain on gentle percussion, further examination by rectal examination has been shown to provide no new information.52 Rectal examination can therefore be avoided in such patients and reserved for those patients without rebound tenderness or where specific pelvic disease needs to be excluded. Measurement of temperature has also been shown to be relatively non-discriminatory in the early assessment of the acute abdomen.53 Urgent urinary microscopy should be carried out on anyone with any symptoms that could relate to the urinary tract and it is a good principle to dip test the urine on admission of every patient with acute abdominal pain.
Initial Blood Investigations And Early Decision-Making
After the initial assessment (history and examination) of patients with acute abdominal pain, steps should be taken towards resuscitation, pain relief and further diagnostic tests as required. There is very good evidence to support the early administration of opiate analgesia in patients with acute abdominal pain, and a recent Cochrane systematic review confirmed that patient comfort was improved without detrimentally affecting surgical decision-making.54
The early administration of opiate analgesia in patients with acute abdominal pain improves patient comfort without adversely affecting clinical decision-making.54
Once the initial assessment has been completed, the surgeon will reach a differential diagnosis and, perhaps more importantly, a clinical decision: early operation definitely required, early operation definitely not required or need for early operation uncertain. Clearly, further investigations in the first category are unlikely to influence management, with the exception of a serum amylase level, which may reveal acute pancreatitis.55 Further investigations in the group in which the surgeon considers early operation is not required can be organised on a more leisurely basis, and it is not surprising that it is in the group in which the surgeon is uncertain as to whether early operation is required that most difficulty exists.56 Most of the uncertainty relates to ‘query appendicitis’, particularly in the young female, but also involves patients with intestinal obstruction and the elderly patient, in whom the diagnosis of mesenteric ischaemia must always be considered.57
Early diagnosis in patients with mesenteric ischaemia is particularly important as survival after surgery is much better in those with venous thrombosis than those with arterial thrombosis.58
In the assessment of the role of subsequent investigations in the acute abdomen, it is important to identify their potential influence on clinical decision-making rather than evaluating them purely on diagnostic potential.
Although blood tests are often useful as a baseline, their influence on the diagnosis of acute abdominal pain remains unclear, with the exception of serum amylase55 and increasingly serum lipase59 or acute pancreatitis (see also Chapter 8). Studies examining the influence of white cell concentration60 and C-reactive protein61,62 in patients with ‘query appendicitis’ have concluded that serial white cell counts are useful (compared with a single measurement). Although isolated C-reactive protein levels may also be fairly non-discriminatory, when they are interpreted with white cell count and both are normal, acute appendicitis is unlikely.63
Overall, inflammatory markers are poor discriminators of conditions such as appendicitis when looked at individually, but when combined and used with history and clinical findings of peritoneal irritation they achieve a high discriminatory power.64 Thus, routine measurement of the white cell count and C-reactive protein in patients with acute abdominal pain can be justified, not only for a baseline with which to compare subsequent levels depending on clinical progress, but also to be interpreted along with all other clinical and biochemical findings.
Liver function tests are of course an essential investigation in the early assessment of the acute abdomen where acute biliary disease is suspected.65
The other area that has attracted great interest in the role of blood tests for aiding diagnosis in the acute abdomen is intestinal ischaemia, whether from strangulated obstruction or mesenteric ischaemia and infarction. Estimation of acid–base status to assess the degree of metabolic acidosis is often a late change and measurement of serum phosphate, lactate, kinase, creatine, lactate dehydrogenase, alkaline phosphatase, diamineoxidase and porcine ileal peptide have all been shown to be unreliable.58 A recent study, however, has demonstrated the use of a combined clinico-radiological score for predicting the risk of strangulation in small-bowel obstruction.66 This will be discussed in more detail later.
With advances in technology and improved radiological techniques, the radiologist is playing an ever more important role in the diagnosis of patients with acute abdominal pain. Furthermore, abdominal ultrasonography and plain radiography evaluated by senior radiologists substantially enhance senior surgical assessment of patients with acute abdominal pain, resulting in reduced surgical admissions.67
The role of plain radiology in the investigation of the acute abdomen has been extensively examined. Until recently there was general consensus that the erect chest radiograph was the most appropriate investigation for the detection of free intraperitoneal gas, with use of the lateral decubitus film if either the erect chest film could not be taken (due to the patient's condition) or was equivocal. This no longer seems to be true following a report from Taiwan, where ultrasonography was shown to be superior to the erect chest radiograph, with a sensitivity of 92% in the detection of pneumoperitoneum compared with only 78% for plain radiology.68 Undoubtedly there will be operator dependence and for now the erect chest radiograph should still be the initial test for suspected perforation (Fig. 5.1). Failure to detect free gas under the diaphragm in a patient with suspected intestinal obstruction can then be further investigated by US, CT or contrast radiology, as discussed below. The erect chest radiograph remains important for excluding chest conditions such as acute lobar pneumonia that can present as acute upper abdominal pain (Fig. 5.2).
FIGURE 5.1 Erect chest radiograph in a patient with a perforated duodenal ulcer. Note the free intraperitoneal air under both hemidiaphragms.
FIGURE 5.2 Erect chest radiograph in a patient with acute right-sided pneumonia.
Plain abdominal radiography is still carried out unnecessarily in a large number of patients,69 and it could be significantly reduced if its use is limited to those patients where it might provide some diagnostic help, such as suspected intestinal obstruction, suspected perforation (Fig. 5.3) and exacerbation of colitis.70
FIGURE 5.3 Plain supine abdominal radiographs demonstrating free intraperitoneal air (a) in a patient with a perforated duodenal ulcer and retroperitoneal air (b) in a patient with perforated diverticular disease.
The use of the supine abdominal radiograph should be limited to patients with suspected intestinal obstruction, suspected perforation and exacerbation of colitis, as indicated in the guidelines produced by the Royal College of Radiologists.71
Similar controversy exists in the use of erect abdominal radiographs for the assessment of patients with suspected intestinal obstruction. Most surgeons still prefer both views (erect and supine) on the basis that in those patients in whom the supine radiograph is normal or equivocal the erect film may be helpful.72
It has been recognised for many years that gastrointestinal contrast studies can be used to evaluate acute gastrointestinal conditions.73 Its main function remains the assessment of both large- and small-bowel obstruction and possible gastrointestinal perforation. However, with the increasing availability of multi-slice CT (see below) this role is dwindling.
Perforated peptic ulcer
Although the erect chest radiograph is recognised as the most appropriate first-line investigation for a suspected perforated peptic ulcer, in approximately 50% of patients no free gas can be identified on the radiograph.74 This leaves the emergency surgeon with three options: (i) to review the diagnosis, such as reconsidering acute pancreatitis; (ii) to proceed to laparotomy based on the clinical findings alone; or (iii) particularly if there are reasonable grounds for uncertainty, to arrange for either a CT with oral contrast or a water-soluble contrast study. The latter will confirm or refute the presence of an ongoing leak (Fig. 5.4), but will not differentiate between the patient without a perforation and one in whom the perforation has sealed. The addition of US,68 as already discussed, and increasingly CT in this scenario may help by revealing free abdominal air and fluid in the patient whose perforation has sealed spontaneously. As has been well understood for quite some time now, many patients with perforated peptic ulcers can be managed non-operatively;75 with this knowledge, the assessing surgeon has plenty of time to resuscitate the patient and make efforts to confirm or refute the diagnosis before rushing to emergency surgery. Patients who might be considered for non-operative treatment of their perforation should have a contrast meal to confirm spontaneous sealing of the perforation. This topic is discussed in more detail in Chapter 6.
FIGURE 5.4 Supine abdominal radiograph taken 20 minutes after the oral administration of 50 mL of water-soluble contrast material in a patient with a suspected perforated peptic ulcer in whom the erect chest radiograph was normal. Note the small trickle of contrast through the perforation. These findings were confirmed at laparotomy. Reproduced from Ellis BW, Paterson-Brown S (eds). Hamilton Bailey's emergency surgery, 13th edn. London: Hodder Arnold, 2000. With kind permission from Taylor Francis.
Surgery for small-bowel obstruction is performed for one of two reasons: first, there has been failure of non-operative management; second, there is clinical suspicion of impending strangulation. Although plain abdominal radiographs are useful in establishing the diagnosis of small-bowel obstruction, they cannot differentiate between strangulated and non-strangulated gut. The criteria on which strangulated intestine must be suspected are well established: peritonism, fever, tachycardia and leucocytosis.76 However, even when the diagnosis is suspected, the changes at operation are often irreversible and resection required. Some workers have looked at serum markers such as phosphate and lactate concentrations58 to help identify patients with possible strangulation in order to allow earlier surgery, but unfortunately they are unreliable. As in other areas of acute abdominal imaging, US also appears to be able to contribute to the diagnosis of intestinal obstruction,77 but the problem of detecting early ischaemic changes in small-bowel obstruction remains largely unsolved. There is little doubt that water-soluble contrast studies in patients with small-bowel obstruction are useful in detecting those patients who are not likely to settle with non-operative management.78 A randomised trial comparing water-soluble contrast follow-through versus conventional management in patients with suspected adhesive small-bowel obstruction demonstrated a significantly shorter time to surgery and therefore overall hospital stay in the group receiving the contrast study.79 Water-soluble contrast material also allows quicker resolution of symptoms.80 In general, failure of water-soluble contrast to reach the caecum by 4 hours strongly suggests that surgical intervention is likely to be required, and better sooner than later (Fig. 5.5). Water-soluble contrast follow-through is also useful in the assessment of early postoperative obstruction in order to identify those patients with an ileus from those with mechanical obstruction who need re-operation.81
FIGURE 5.5 Supine abdominal radiograph in a patient with adhesive small-bowel obstruction (a), 90 minutes (b) and 4 hours (c) after oral administration of 50 mL of water-soluble contrast material. Note failure of contrast to reach the caecum and the obvious small-bowel obstruction. Laparotomy confirmed small-bowel obstruction due to adhesions. (d) A post-contrast 4-hour film in a patient with suspected small-bowel obstruction from the plain abdominal radiograph but on this occasion contrast has reached the colon by 4 hours and no surgery was required.
In patients with small-bowel obstruction early administration of a water-soluble contrast material should be considered as it allows those patients who require surgery to be identified sooner and those that will settle non-operatively to do so quicker than patients managed conventionally.79,80 A systematic review and meta-analysis of the diagnostic and therapeutic role of water-soluble contrast in adhesive small-bowel obstruction found that it was effective in predicting the need for surgery, as well as actually reducing the need for operation and shortened hospital stay.82
A recent clinicopathological score has been developed to predict the risk of strangulated small-bowel obstruction66 and is discussed in more detail below under CT imaging. More detailed information on the surgical management of small-bowel obstruction is provided in Chapter 9.
The management algorithm for large-bowel obstruction has now become well established following the more widespread recognition that colonic pseudo-obstruction could not be distinguished from mechanical obstruction on plain radiographs alone (Fig. 5.6a,b).83 The decision that all patients with suspected large-bowel obstruction should now undergo a contrast enema (Fig. 5.6c,d) before laparotomy has probably been the most important factor in reducing not only the unnecessary operation rate for pseudo-obstruction, but also the associated mortality. Patients with acute colonic pseudo-obstruction present with similar history and clinical signs to the patient with a mechanical obstruction. Although factors recognised as precipitating pseudo-obstruction, such as dehydration, electrolyte abnormalities, pelvic and spinal surgery, acid–base imbalance and so on, may alert the clinician as to the possible cause, it cannot be confirmed without further investigation. As the treatment for one is non-operative and for the other is usually operative, accurate assessment is essential.
FIGURE 5.6 Supine abdominal radiographs in two patients with large-bowel obstruction. (a) Patient A has pseudo-obstruction. (b) Patient B has mechanical obstruction. (c,d) Water-soluble contrast enema confirmed pseudo-obstruction in patient A (c) and an obstructing carcinoma of the sigmoid colon in patient B (d).
All patients with a suspected large-bowel obstruction should undergo some form of contrast examination to exclude pseudo-obstruction.83
The surgical management of both large-bowel obstruction and the next topic, acute diverticulitis, is covered in more detail in Chapter 10.
The majority of patients who present with symptoms and signs of acute diverticulitis can be managed non-operatively, with the exception of those patients who have overt peritonitis from perforation. Although US in experienced hands might identify a thickened segment of colon, perhaps with an associated paracolic collection of fluid, invariably there is too much gas for adequate assessment and quite significant collections can go unnoticed. For this reason clinicians have attempted to evaluate other modalities, such as water-soluble contrast radiology and CT. The former has the ability to identify an ongoing ‘leak’, the latter a perforation and collection. Both of these pieces of information may be of use to the surgeon in reaching a decision to operate, even though the ultimate decision must be based on clinical rather than radiological criteria. Overall, CT has been shown in a prospectively randomised trial to be superior to contrast enemas in both the evaluation of inflammation and identification of a collection.84
The use of US is now one of the mainstays of investigation of the acute abdomen. Accurate detection of small amounts of intraperitoneal fluid associated with conditions such as perforated peptic ulcer, acute cholecystitis, acute appendicitis, strangulated bowel and ruptured ovarian cysts can be very helpful in alerting the clinician to the possible severity of the patient's symptoms. Furthermore, reports on the accuracy of US in the detection of specific conditions such as acute cholecystitis and appendicitis are impressive. The presence of free fluid, gallstones, a thickened gallbladder wall and a positive ultrasonographic Murphy sign are all good indicators of acute cholecystitis.85 US is the first-line investigation for acute biliary disease, with a sensitivity greater than 95% for the detection of acute cholecystitis.86 As the most appropriate management of these patients is now laparoscopic cholecystectomy during the same admission, and if possible within 48 hours,87 early US examination on any patient with suspected acute biliary disease should be undertaken soon after admission (see alsoChapter 8).
In experienced hands US has been shown to be able to detect an acutely inflamed non-perforated appendix with a sensitivity of 81% and specificity of 100%.88 Because the technique relies on visualising a non-compressible swollen appendix (Fig. 5.7), the sensitivity for perforated appendicitis is much lower (29%). When a scoring system is used for both clinical diagnosis and ultrasonographic findings, the addition of the latter increases the diagnostic accuracy for acute appendicitis.89,90 Clearly, it would be inappropriate to scan everyone with suspected appendicitis, but where the diagnosis is uncertain, particularly in women, the case for US scanning is strong, as many alternative diagnoses can be detected.91
FIGURE 5.7 Ultrasound examination on a patient with acute appendicitis. Note the non-compressible thick-walled hollow organ (appendix) beneath the probe.
Other areas where US is specifically used to assess the acute abdomen are abdominal aortic aneurysms, renal tract disease and acute gynaecological emergencies. US may also have a role to play in the diagnosis of strangulated small-bowel obstruction, by detecting dilated non-peristaltic loops of bowel in association with free intraperitoneal fluid.92 US can also be useful in detecting acute abdominal wall problems, such as rectus sheath haematoma (Fig. 5.8), and differentiating them from intra-abdominal pathology.93 US also has a role in the early assessment of patients with blunt abdominal trauma,94 and this is covered in detail in Chapter 13.
FIGURE 5.8 Ultrasound of the abdominal wall demonstrating a rectus sheath haematoma.
Computed Tomography (CT)
The place of CT in the early assessment of the acute abdomen has received wide attention over the last few years following the introduction of multislice CT and recognition of the excellent images that can be produced, especially if intravenous (i.v.) contrast is used. Its role in the investigation of the severity of acute diverticulitis has already been discussed84 and it can also be used to identify miscellaneous intra-abdominal collections resulting from other conditions. Attempts to improve the diagnostic accuracy of acute appendicitis using CT have been impressive, with 98% accuracy in 100 consecutive patients with suspected appendicitis (Fig. 5.9), of whom 53 had acute appendicitis.95 However, irrespective of the cost and availability issue, the diagnosis of acute appendicitis can usually be made without the aid of imaging studies and care must be taken to ensure that such investigations are used to complement rather than to replace the clinical assessment of patients with suspected appendicitis.96 Because of the associated risks of i.v. contrast in some individuals as well as excessive radiation exposure, particularly in the younger patients, the role of non-contrast CT has been examined in a systematic review of seven studies.97 This review concluded that non-contrast helical CT provides an acceptably high accuracy (sensitivity of 92.7% and specificity of 96.1%) for the diagnosis of acute appendicitis in adult patients.
FIGURE 5.9 CT image with intravenous contrast demonstrating perforated appendicitis.
A randomised study from Cambridge that examined the effect of early CT (within 24 hours of admission) compared to standard investigations on patients with undifferentiated acute abdominal pain demonstrated an improvement in diagnostic accuracy in patients undergoing early CT, but no difference in length of stay or mortality.98 Further analysis of the same data demonstrated that another advantage of early CT was in the detection of unexpected significant primary and secondary diagnoses.99 These findings were confirmed in another more recent randomised trial comparing plain radiology with early low-dose abdominal CT.100 In addition to its overall role in the investigation of the acute abdomen, CT is also extremely useful specifically in the detection of gastrointestinal obstruction (Fig. 5.10), perforations (Fig. 5.11), along with indications of the site of perforation,101 intestinal ischaemia (Fig. 5.12)102and bleeding (Fig. 5.13), as well as abdominal wall problems (Fig. 5.14). Multislice CT with intravenous and rectal contrast can also be useful in the detection and differentiation of different types of colitis, including ulcerative, Crohn's, pseudo-membranous and Clostridium difficile colitis.103 A clinicoradiological score has recently been developed to predict the risk of strangulated small-bowel obstruction using duration of pain (lasting 4 days or more), elevated C-reactive protein (> 75 mg/L), leucocyte count (> 10 × 109/L), the presence of guarding, at least 500 mL of fluid as seen on CT and reduced enhancement of the small bowel on CT. The risk of ischaemia in 233 consecutive patients studied with small-bowel obstruction was 6% in patients with a score of 1 or less (one point for each variable) compared to a sensitivity of 67.7% and specificity of 90.8% in requiring resection for a score of 3 or more.66 Overall, 138 of the patients in this study underwent surgery, of whom 45 required intestinal resection.
FIGURE 5.10 CT image with intravenous contrast demonstrating small-bowel obstruction due to an incarcerated inguinal hernia. With thanks to Dr Dilip Patel, Consultant Radiologist, Royal Infirmary, Edinburgh.
FIGURE 5.11 (a) Sagittal view of a CT scan with intravenous contrast demonstrating free intraperitoneal gas from a perforated peptic ulcer. Note the free air anterior to the liver. (b) Axial view of the same patient showing free air above the liver. With thanks to Dr Dilip Patel, Consultant Radiologist, Royal Infirmary, Edinburgh.
FIGURE 5.12 CT angiogram demonstrating coeliac axis thrombus.
FIGURE 5.13 CT angiogram demonstrating contrast in the mid descending colon from bleeding diverticular disease.
FIGURE 5.14 CT image with intravenous contrast demonstrating a large rectus sheath haematoma.
Despite the relatively high diagnostic accuracy of CT in the assessment of the acute abdomen, and particularly acute appendicitis, the main drawbacks remain cost and radiation exposure.104 As a result the role of CT in the early assessment of patients with acute abdominal pain should still be limited to those in whom there remains uncertainty as to either diagnosis or decision to operate after initial assessment.
Magnetic Resonance Imaging (MRI)
With the increased use of CT in the investigation of the acute abdomen it was only a matter of time before attention turned to the role of MRI, which is not associated with the radiation exposure of CT. MRI can undoubtedly differentiate an acutely inflamed appendix from a normal one105 and therefore is useful in pregnant patients, where the diagnosis of acute appendicitis can be difficult.106 However, a review of academic centres in North America reported that radiologists still preferred CT to MRI in the second and third trimester to investigate acute abdominal pain.107
Laparoscopy is now an integral part of the emergency surgeon's armamentarium, for both diagnosis and treatment of acute abdominal conditions. Laparoscopy significantly improves surgical decision-making when used as a diagnostic tool,108 particularly when the need for operation is uncertain.56 With the increasing use of laparoscopic appendicectomy (see Chapter 9), most patients with suspected appendicitis can now undergo diagnostic laparoscopy followed by laparoscopic appendicectomy if the diagnosis of acute appendicitis is confirmed (Fig. 5.15). Even if a policy of laparoscopic appendicectomy is not followed, all females with suspected acute appendicitis should still undergo diagnostic laparoscopy because the diagnostic error is more than twice that of males,109 usually due to underlying gynaecological conditions (Figs 5.16 and 5.17). When used as a diagnostic tool in patients admitted to hospital with suspected acute non-specific abdominal pain, some of whom of course subsequently turn out to have a surgical cause, early laparoscopy versus observation has been shown to be of benefit. Two randomised studies110,111 have demonstrated that the associated improved diagnostic accuracy in the patients undergoing laparoscopy converts to a reduced hospital stay, and in one of the studies110 an improved quality of life (assessed 6 weeks after discharge from hospital).
FIGURE 5.15 Laparoscopy showing an acutely inflamed appendix with pelvic peritonitis.
FIGURE 5.16 Laparoscopic view of a torsion of the right fallopian tube with ischaemia of the distal tube and ovary.
FIGURE 5.17 Laparoscopic view of a haemorrhagic ovarian cyst.
The decision on what to do if a normal appendix is seen at laparoscopy is discussed in detail in Chapter 9, and there are differing arguments for and against its removal. What is essential is that the patient must be clearly told the diagnosis made at laparoscopy and the procedure performed. It has been shown that around 27% of patients undergoing laparoscopy for acute abdominal pain could either not remember what had happened or their recall was incorrect.112 This included knowledge as to whether the appendix had been removed or not.
It is clear that there is now overwhelming evidence in support of the use of diagnostic laparoscopy in the management of patients with acute abdominal pain in whom the need for surgery is uncertain and particularly women with suspected appendicitis.108,110,111