Congenital positional anomalies of the colon: radiographic diagnosis and clinical implications. II. Abnormalities of fixation.

Defective fixation during embryologic development is responsible for a variety of segmental colonic malpositions seen during barium enema examinations. A review of the normal development process of fixation is presented, together with the most common and significant aberrations. On the right side clinical entities such as axial torsion, cecal bascule, retrocolic sigmoid, and pericolic bands are discussed and illustrated. On the left side, the configuration and clinical implications of the malposition of the splenic flexure are analyzed. It is pointed out that reversed configurations of the splenic flexure associated with failure of fixation of the entire descending colon may occur as an isolated congenital abnormality and may not necessarily be associated with renal anomalies. The characteristic radiographic appearance of the persistent descending mesocolon and its potential for complications is in addition emphasized. Familiarization with the radiographic appearance and clinical implications of these common abnormalities is essential in the daily interpretation of barium enema examinations.