ANSWER 41 This woman has acute appendicitis. Acute appendicitis classically presents with a short history of central abdominal pain which rapidly localizes to the right iliac fossa. There is guarding and ‘board-like’ rigidity and rebound tenderness in the right iliac fossa. Untreated, some cases will resolve spontaneously, whereas others will perforate leading to localized or generalized peritonitis. Rarely a delayed diagnosis may result in acute appendicitis progressing to an appendix mass consisting of a haemorrhagic oedematous mass in the ileocaecal region. In this woman the right iliac fossa symptoms and signs together with the raised white cell count and CRP are consistent with appendicitis. The symptoms of loin pain and presence of blood and protein in the urine mimicking a urinary tract infection suggest the appendix may be retrocaecal. Patients with retro-ileal appendicitis often have little abdominal pain, but irritation of the ileum can lead to severe diarrhoea and vomiting. Patients may also present with subacute intestinal obstruction due to intestinal ileus, or urinary retention due to pelvic peritonitis.
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Differential diagnosis of acute appendicitis • In young adults the differential diagnoses include irritable bowel syndrome, nonspecific mesenteric adenitis, ruptured ectopic pregnancy, twisted or haemorrhagic ovarian cysts, infection of the Fallopian tubes and urinary tract infections. • In older patients perforated peptic ulcers, diverticulitis, Crohn’s disease and carcinoma of the colon are important differential diagnoses.
The treatment is appendicectomy as soon as urinary tract infection has been excluded. Ultrasound or computed tomography (CT) scanning can be performed if there is uncertainty as to the clinical diagnosis. However a significant number of patients will have a normal appendix removed.
KEY POINTS
• Retrocaecal appendicitis can mimic acute pyelonephritis. • In young women ectopic pregnancy and gynaecological pathology can mimic appendicitis.
• Elderly patients may present with atypical symptoms and signs.
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