Malposition of the colon in right renal agenesis, ectopia, and anterior nephrectomy.

Right renal agenesis, ectopia, or anterior nephrectomy can be identified by a characteristic malposition of the right colon. Barium enemas show that the posterior portion of the right colic (hepatic) flexure occupies the area of the right renal fossa. This change in position of the right colon was not observed as a normal variant in 100 randomly selected patients but was present in each of eight patients with agenesis, ectopia, or anterior nephrectomy. This malposition should not be mistaken for internal hernia, malrotation, or displacement by tumor mass or organomegaly. Nonvisualization of the right kidney on excretory urography with normal position of the colon excludes agenesis or ectopia as diagnostic considerations.