Although anomalies of the venous system are fairly frequent, those of the inferior vena cava are comparatively uncommon.
The human inferior vena cava is of complex origin (Fig. 1). It is derived from elements of nearly all the trunk veins of the embryo.1 During the sixth, seventh, and eighth weeks of development, rapid changes take place in the mesonephros and the blood vessels associated with it. The postcardinal veins are the dorsal vessels of the mesonephros. They and the subcardinal veins, which lie ventromesially, are the dominant trunk vessels in the sixth week of development. The supracardinal veins which lie dorsomesial to the postcardinals develop rapidly during the seventh week. The posterior portion of the right supracardinal vein eventually becomes the postrenal vena cava of the adult. The left supracardinal vein largely disappears. By the end of the eighth week of intrauterine growth, the adult pattern has been established.