Congenital positional anomalies of the colon: radiographic diagnosis and clinical implications. I. Abnormalities of rotation.

Positional anomalies of the colon may be explained by an arrest in the normal development process of the distal midgut. Aberrations involving the incipient stages of rotation lead to severe malpositions, while those involving the latter stages to milder forms. The normal embryology of the distal (postarterial) segment, as well as forms of complete and partial nonrotations, are discussed and illustrated. A survey of 39 consecutive cases of rotational abnormalities of the midgut with special emphasis on the configuration of the colon is presented. There is a high incidence of associated failure of fixation resulting in mobile colons that can be demonstrated radiographically. In addition, the great majority of colonic malrotations demonstrate rotational abnormalities involving the proximal intestinal tract. Their clinical implication is related to the presence of other incidental congenital anomalies or to complications derived from faulty mesenteric fixations such as peritoneal bands, adhesions, kinking, or intestinal volvulus.