Left-sided inferior vena cava. Report of a case occasionally encountered while performing an aorto bifemoral bypass and review of the literature.

We present a case of left-sided inferior vena cava unexpectedly observed during an operation of aorto bifemoral bypass in a patient with severe Leriche syndrome and almost complete obstruction of the infrarenal aorta. This very rare congenital malformation (0.2-0.5%) was not recognized by the duplex scanner performed preoperatively, probably because of the low level of suspicion carried on by an experienced operator. AngioCT or angioMR, which would have surely shown us the anomaly, were not done because, in the lack of an aneurysmal disease or other abdominal pathological situations, these investigations were not required before operation. The possible hazards of such an unrecognized malformation are great, mostly in terms of incontrollable intraoperative hemorrhages, but the final outcome of this case was positive.