This is the commonest cause of the acute abdomen. It usually occurs when there is an obstruction in the lumen of the appendix either by a faecolith or foreign body or by enlargement of lymphoid follicles in its wall. It most often affects children, teenagers and young adults. It is rare at the extremes of life. In the infant, the lumen of the appendix is wide in relation to the remainder of the bowel and the diet is soft and hence, obstruction within the lumen is less likely. In the elderly, the lumen tends to be obliterated.
Rarer causes of appendicitis include carcinoma of the caecum obstructing the appendiceal lumen, carcinoid tumour and obstructing fibrous bands. Occasionally a carcinoma obstructing the lumen of the appendix will cause it to distend and fill with mucus, i.e. a mucocele of the appendix.
- Central abdominal cramping or colicky pain.
- Vomiting is uncommon.
- Occasionally the patient may pass a loose stool. Frank diarrhoea is uncommon.
- Central abdominal pain lasts approximately 8 h. It is followed by the development of a sharp, stabbing somatic type of pain in the RIF made worse by coughing or moving.
- Low-grade pyrexia (37.2–37.8C) Flushed.
- Characteristic fetor (sweet faecal smell to breath).
- White furred tongue.
- Tachycardia (100 in first 24 h).
- Tender with guarding in RIF over McBurney’s point.
- Examination PR: tender anteriorly in the rectovesical or rectouterine pouch.
In elderly patients there may be confusion and later, shock may develop.
- Pointing sign – The patient is asked to point to where the pain began and where it moved.
- Rovsing’s sign – Deep palpation of the left iliac fossa may cause pain in the right iliac fossa.
- Psoas sign – Occasionally, an inflamed appendix lies on the psoas muscle, and the patient, often a young adult, will lie with the right hip flexed for pain relief.
- Obturator sign – Spasm of the obturator internus is sometimes demonstrable when the hip is flexed and internally rotated. If an inflamed appendix is in contact with the obturator internus, this manoeuvre will cause pain in the hypogastrium
- WCC: usually >10 109/L with neutrophil leukocytosis
- USS: may show a mass or abscess; usefulness in early appendicitis depends on the experience of the ultrasonographer
- Diagnostic laparoscopy.
- In the classical case of acute appendicitis there are few
conditions that enter into the differential diagnosis. These include mesenteric adenitis, Meckel’s diverticulitis, Crohn’s disease (regional ileitis), mesenteric embolus and right-sided colonic diverticulitis. All these conditions will initially
cause central abdominal cramping pain with subsequent tenderness in the RIF.
- The treatment of acute appendicitis is appendicectomy. Prophylactic metronidazole by suppository should be given 1h preoperatively to reduce the risk of wound infection.
Appendicitis may resolve spontaneously. The appendix may
become surrounded by adjacent small bowel and omentum and give rise to an appendix mass. It may perforate giving rise to generalized peritonitis or it may perforate amidst local adhesions giving rise to an appendix abscess. Often it is difficult to diagnose appendicitis. If the symptoms have been present for 48 h (‘48 h rule’) and the diagnosis is truly appendicitis, then the patient should either have developed an appendix mass or generalized peritonitis. If neither of these two is present, then the diagnosis of appendicitis should be reviewed.