A 62-year-old man was admitted with generalised abdominal pain, constipation and vomiting. His abdomen was markedly distended and tender on general examination with signs of local peritonism in the left iliac fossa. He was initially diagnosed with likely acute diverticulitis and treated conservatively. A CT scan the next day showed fluid filled, dilated small bowel loops consistent with small bowel obstruction and there was a suggestion of an abscess in the left iliac fossa region. An urgent laparotomy was performed, which identified a perforated Meckel diverticulum.