[Anomalies of the inferior vena cava: observations on the anterior approach to the vertebral column].

The inferior vena cava is formed through a complex process of embryogenesis from the sixth to the tenth week of gestation. Improper completion of the process of embryogenesis may result in four anatomic anomalies: 1) duplication of the inferior vena cava; 2) left-sided inferior vena cava; 3) retroartic left renal vein and 4) circumaortic left renal vein. The Authors report the cases of two patients in which duplication of the inferior vena cava and retroartic left renal vein were respectively observed. The importance to avoid injuries and subsequent bleeding from these anomalous structures during surgical operations is stressed. Moreover, a correct preoperative diagnosis may reduce these complications.