The variable anteroposterior position of the retroperitoneal colon to the kidneys.

Five hundred supine abdominal CT scans were reviewed retrospectively to determine the variation of colonic position about each kidney. The anteroposterior position of the retroperitoneal colon was evaluated for different age groups and sexes at the level of the upper-, mid-, and lower-renal poles. The ascending/descending colon generally assumed a more posterior position about the lower poles and left kidney vs. the upper poles and right kidney. There were few significant differences between the sexes and among different age groups with two exceptions. In middle-aged and older women, the descending colon lay more lateral to the left lower kidney than in their male counterparts. Second, although the colon was located behind the kidney (retrorenal colon), in a nearly equal number of men and women, most patients with this colonic position were 60 years of age or older and had it about their lower renal poles. The overall frequency of retrorenal colon in the supine patient was 1.9%.