Read Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice Online
Authors: Simon Paterson-Brown MBBS MPhil MS FRCS
Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice (46 page)
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.
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.