ANSWER 41
This woman has acute appendicitis. Acute appendicitis classically presents with a short his-
tory of central abdominal pain which rapidly localizes to the right iliac fossa. There is guard-
ing 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 gener-
alized 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 appen-
dix 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 reten-
tion due to pelvic peritonitis.
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 uncer-
tainty as to the clinical diagnosis. However a significant number of patients will have a
normal appendix removed.
- 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.
KEY POINTS
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- In young adults the differential diagnoses include irritable bowel syndrome, non-
specific 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.
Differential diagnosis of acute appendicitis