Cecal volvulus in complete common mesentery.

Common mesentery is an abnormal rotation of the primary umbilical loop characterized by inverted positioning of the mesenteric vessels; the mesenteric vein is displaced to the left of the artery. The inversion can be complete or incomplete. If it is incomplete, the mesenteric root is very short, with an empty right iliac fossa and the caecum in high median or subhepatic position. If it is complete, the entire small intestine is on the right, the entire large intestine is on the left; there is no third duodenum, and the second duodenum is anastomosed in the jejunum to the right of the superior mesenteric vessels. Cecal volvulus is a rarely encountered cause of acute intestinal occlusion and should be considered as a surgical emergency. There exist two main types of volvulus: by twisting of the large intestine around its axis, which remains in place; or by tilt and to rotation of the colon, which changes position.