Mesenteric defects as a cause of intestinal volvulus without malrotation and as the possible primary etiology of intestinal atresia.

Mesenteric defects can lead to intestinal volvulus even when the midgut is normally rotated. There are two types of mesenteric defects: basilar, in which the entire base of the mesentery is involved, and segmental, in which only an isolated portion of the mesentery is affected. These defects can present at any age, and the clinical symptoms depend on the extent of the disease and the amount of intestine involved in the volvulus. In the newborn, the basilar defects have clinical signs and symptoms similar to those of midgut volvulus secondary to malrotation. Similar to midgut volvulus secondary to malrotation, this is a surgical emergency. In older patients, basilar defects can be misdiagnosed because of the normal placement of the ligament of Treitz and because of failure to consider mesenteric defects as a possible cause. The treatment for basilar mesenteric defects is intestinal fixation. Intestinal volvulus secondary to segmental defects always presents as intestinal obstruction. In the newborn, these lesions may be indistinguishable from intestinal atresia. Older children present with intestinal obstruction of an unknown cause. Resection of the affected intestine is the treatment for segmental mesenteric defects. Intestinal mesenteric abnormalities as a cause of intestinal atresia unifies under one etiology all the lesions observed in intestinal atresia. Although this theory does not rule out other causes of intestinal atresia, intestinal mesenteric defects may be the primary condition under which intestinal atresia occurs.