Congenital single, pelvic iliac artery: a case report.

Congenital vascular anomalies of pelvis and lower limb arteries are rare. During embryologic development, the sciatic artery represents the dominant supplier of blood to the lower limb. The external iliac and femoral arteries appear later in the process and take over as the sciatic artery regresses. Failure of the sciatic artery to regress creates a persistent sciatic artery malformation. Failure of the external iliac artery to properly bud may lead to similar vascular malformations. The authors present a patient with atresia of the left external iliac artery with an associated atresia of the left common iliac vein, duplication of the infrarenal inferior vena cava, and absence of the left S1 bony arch. The left-sided single iliac artery supplies both pelvic structures and the lower limb. The "pelvic" external iliac artery may result from embryologic budding at a lower segmental level than the usual fifth lumbar segmental artery. This combination of anomalies suggests an abnormality of segmentation on left at the first sacral level.