A frequent obstructive anomaly of the mouth of the left common iliac vein

Abstract

This study of the opening of the left common iliac vein into the inferior vena cava is based on the examination of 412 bodies: 97 stillborn babies and infants up to 10 months old, 28 children from 1 to 9 years of age, 23 adolescents from 10 to 19 years of age, and 264 adults up to 90 years of age. The width of the opening first increased rapidly with increasing age, and later more slowly. The curve reached its peak during the seventh decade. A valve was found to be normally present in the newborn at the lower pole of the opening, but it appeared to be worn off in an ever greater percentage as age progressed, and more so in obstructed than in normal openings. This observation seems to be significant with regard to the cause of varices of the lower extremities, which have often been explained as a result of venous valvular insufficiency. Obstruction of the orifice in the 399 cases analyzed was observed in 95 instances (23.8 per cent), with a possibility of 16 more instances in the stillborn and infants. It was less common in children and babies (4.7 per cent), although, if the 16 doubtful cases are included, the percentage rises to 17.3 per cent. In those over 10 years of age, it was found 89 times (33.8 per cent). It occurred with equal frequency in males and females, and in whites and Negroes. According to location and other criteria, the obstructions could be divided into five groups (Figs. 3 and 4). The most common site of obstruction was the upper pole of the orifice, where two-thirds of all obstructions were found. Concerning the pathogenesis of the obstructions, few, if any, were thought to be caused by faulty development, per se. They appeared to be acquired during the growth period, rarely before birth, and rarely after adolescence. As to the mechanism involved, it was observed that the obstructions occurred at a point where the right iliac artery crosses and exerts pressure on the vein. This pressure conceivably interferes with the proper development of the opening into the vena cava or causes an injury resulting in organization and fibrosis. In a small number of cases the obstructions could be shown to be organized thrombi. The clinical significance of the obstructions is apparent from the greater frequency of thrombosis in the left than in the right leg. This preponderance could be confirmed in our material, as well as in an analysis of 1,000 consecutive autopsies from one of our hospitals.