[A woman with right-sided abdominal pain].

A 59-year-old woman presented with right-sided abdominal pain. Ultrasound was suggestive of acute appendicitis. Laparoscopy showed inflammation of a solitary caecal diverticulum, a rare congenital malformation. Uncomplicated caecal diverticulitis can mimic appendicitis clinically and sonographically, but does not require surgical intervention. An additional CT-scan can clarify the diagnosis.