Spread of disease via the subperitoneal space: the small bowel mesentery.

The designation of the subperitoneal space emphasizes the continuum of the potential space of extraperitoneal and intraperitoneal areolar tissue traversed by blood vessels, lymphatics, and nerves. Across its root, the subserous connective tissue of the small bowel mesentery is anatomically continuous with that deep to the posterior parietal peritoneum. There is thereby provided an avenue of spread from multiple sites to and from the small bowel mesentery and its relationships. These include perforated lesions of the bowel, pancreatitis, lymphoma, neuroblastoma, leiomyosarcoma of small bowel, and hemorrhage of retroperitoneal and pelvic origin.