Anomalous inferior vena cava associated with horseshoe kidneys.

Two cases are presented in which anomalies of the inferior vena cava were associated with horseshoe kidneys. Radiological demonstration of such combined variation is rare, only one case of duplicated inferior vena cava with horseshoe kidney having been found in the literature. The embryological basis for these anomalies is reviewed. A possible explanation for their coexisting occurrence is also speculatively raised.