Pyogenic sacroiliitis: another imitator of the acute abdomen.

Acute suppurative infection of the sacroiliac joint can mimic the acute abdomen. Experience with a patient who had exploratory laparotomy for acute appendicitis prompted a review of the literature, which indicated that 12.6% of patients with pyogenic sacroiliitis have acute abdominal pain. A high index of suspicion is necessary to establish this diagnosis.