Self-assessment Questions

25 Acute appendicitis

• 1.What is the most common abdominal emergency?

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  Acute appendicitis.

• 2. What causes an acute appendicitis?

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  Acute appendicitis usually occurs when the appendix is obstructed by a faecolith or foreign body in the lumen, by a fibrous stricture in its wall from previous inflammation, or by enlargement of lymphoid follicles in its wall secondary to inflammation of its mucosa; rarely it is associated with an obstructing carcinoid tumour near its base. Occasionally, acute appendicitis occurs proximal to an obstructing lesion (usually carcinoma) in the caecum or ascending colon.

• 3. In which age group does acute appendicitis occur and why?

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  As the appendix in the infant is wide mouthed and well drained, and as the lumen of the appendix is almost obliterated in old age, appendicitis at the two extremes of life is relatively rare. However, when it does occur in these age groups it is poorly tolerated, and often diagnosed late.

• 4. What happens to the appendix once it has been obstructed?

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  The obstructed appendix acts as a closed loop; bacteria proliferate in the lumen and invade the appendix wall, which is damaged by pressure necrosis. The vascular supply to the appendix is made up of end-arteries, which are branches of the appendicular branch of the ileocolic artery. Once these are thrombosed, gangrene is inevitable and is followed by perforation.

• 5. Which artery supplies the appendix?

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  Branches of the appendicular branch of the ileocolic artery.

• 6. How long do the pathological changes of appendicitis take to develop once obstruction of the appendix has occurred?

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  There is no strict time relationship for this chain of events. An appendix may occasionally perforate under 12 hours, but conversely it is not rare to see an acutely inflamed but not perforated appendix after 3 or 4 days. The effects of appendicular obstruction depend on the content of the appendix lumen. If bacteria are present, acute inflammation occurs; if, as sometimes happens, the appendix is empty, then a mucocele of the appendix results, owing to continued secretion of mucus from the goblet cells in the mucosal wall.

• 7. What happens when an empty appendix is obstructed?

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  A mucocele will form, because of continued secretion of mucus from the goblet cells in the mucosal wall.

• 8. Which cells in the appendix secrete mucous?

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  Goblet cells.

• 9. Can appendicitis occur in a non-obstructed appendix? How?

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  Occasionally, appendicitis can occur in the non-obstructed appendix. Here there may be a direct infection of the lymphoid follicles from the appendix lumen, or in some cases the infection may be haematogenous (e.g. the rare streptococcal appendicitis). The non-obstructed acutely inflamed appendix is more likely to resolve than the obstructed form.

• 10. What is the pathological course of acute appendicitis?

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  The acutely inflamed appendix may resolve, but if so a further attack is likely. It is not uncommon for a patient with acute appendicitis to confess to one or more previous milder episodes of pain, the ‘grumbling appendix’. More often the inflamed appendix undergoes gangrene and then perforates, either with general peritonitis or, more fortunately, with a localized appendix abscess.

• 11. How do patients with acute appendicitis typically present?

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  The vast majority of patients with acute appendicitis present with marked localized pain and tenderness in the right iliac fossa.

• 12. What is the nature of the pain of acute appendicitis?

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  Typically the pain commences as a central periumbilical colic, which shifts after approximately 6 hours to the right iliac fossa or, more accurately, to the site of the inflamed appendix as the adjacent peritoneum becomes inflamed. The appendix is a long tube (7–10 cm long), tethered proximally to the caecum near the ileocaecal junction; distally, the tip may lie anywhere from behind the caecum (retrocaecal), adjacent to the ileum, or down in the pelvis lying against the rectum or the bladder. Thus, if the appendix is in the pelvic position, the pain may become suprapubic, with urinary frequency as the bladder is irritated; if it is in the high retrocaecal position, the symptoms may become localized to the right loin with less tenderness on abdominal palpation. Rarely, the tip of the inflamed appendix extends over to the left iliac fossa and pain may localize there. The colicky central abdominal pain is visceral in origin, the shift of pain is due to later involvement of the sensitive parietal peritoneum by the inflammatory process. Typically, the pain is aggravated by movement and the patient prefers to lie still with the hips and knees flexed.

• 13. What are the three positions in which the appendix can lie?

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  Correct answer:

  (1) Distally the tip may lie anywhere from behind the caecum (retrocaecal); (2) adjacent to the ileum, or (3) down in the pelvis lying against the rectum or bladder.