Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice (47 page)
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Authors: Simon Paterson-Brown MBBS MPhil MS FRCS
Appendix mass
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.
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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.
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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.
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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.
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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.
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,
54
,
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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.
As mentioned above, there is certainly a group of patients who suffer from recurrent appendicitis
45
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.
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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.
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.
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Recognition of the risk associated with negative appendicectomy
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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,
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and this has influenced the results of a subsequent systematic review.
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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.
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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.
Hospital stay
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 activities
36
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 appendicectomy
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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.
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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.
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,
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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.
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,
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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.
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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,
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a more recent historical cohort study revealed no long-term consequence on fertility.
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Key points
The main emergency conditions affecting the small bowel are obstruction, haemorrhage and ischaemia.
Early management requires adequate clinical and radiological assessment, which might include contrast radiology and, increasingly, CT (see also
Chapter 5
).
Early appendicectomy for acute appendicitis is better than non-operative treatment with antibiotics because of a high recurrence rate.
Laparoscopic appendicectomy results in less pain and faster return to normal activities than open appendicectomy but there may be a higher risk of postoperative abscess formation.
A non-operative approach is indicated in the majority of patients with appendix mass or abscess, with radiological drainage as required. Subsequent interval appendicectomy is only indicated in those patients with recurrent symptoms. Care must be taken to ensure that underlying disease other than appendicitis has been excluded (e.g. caecal carcinoma and Crohn's disease).