Superior, inferior and paraduodenal recesses, potential sites of internal hernia
Expansion
Small peritoneal pockets lie around the duodenojejunal flexure, formed by folds of peritoneum during the fusion of the duodenal mesentery to the posterior wall:
- Superior duodenal recess
- Inferior duodenal recess
- Paraduodenal recess (fossa of Landzert) - on the left
- Retroduodenal recess
They are usually of no consequence, but a loop of small bowel can enter one and become trapped, a paraduodenal internal hernia, which accounts for over half of all internal hernias.
The key clinical point is that an internal hernia causes obstruction with no external lump and no previous surgery, so it is easily missed. It is diagnosed on computed tomography by an abnormal clustering of small bowel loops in an unexpected location, often with swirling of the mesenteric vessels.
Similar recesses exist around the caecum and the sigmoid mesocolon.