[A man with swollen abdomen, abdominal pain and nausea].

A 45-year-old man presented with acute intestinal obstruction, due to congenital peritoneal encapsulation. This rare malformation leads to an accessory peritoneal sac around all or part of the small bowel. Torsion of this sac can lead to acute bowel obstruction and therefore ischaemia. In this case, detorsion and adhesiolysis resulted in a positive outcome.