Bilateral persistent sciatic vein: report of a case with developmental, histological and clinical aspects

Bilateral large variant veins were encountered in the lower extremity. It was aimed to identify the structural characteristics of this rare case and then, regarding the structural features, to overview its formation process and denomination.

During the routine dissection of a 93-year-old male cadaver, bilateral large variant veins were found at the thigh. Valves of the veins were examined and evaluated together with the vascular wall histology.

The variant vein was loosely attached to the sciatic nerve by fibrous tissue and had anastomoses with the popliteal vein in the popliteal fossa on each side. The popliteal veins were hypoplastic on both sides. The right variant vein was passing through the fibers of the adductor magnus muscle 56.2 mm above the adductor hiatus, which corresponds to the third perforating branch of deep femoral vein. The left one was turning to the front over the adductor magnus muscle, at the lower border of quadratus femoris muscle. The left variant vein was corresponding to the descending branch of the medial circumflex femoral vein. Both variant veins had one incomplete and three well-developed valves.

In accordance with the findings, the variant vein was concluded to be an embryonic remnant, rather than an acquired one subsequent to any obstruction of the femoral vein. Regarding their connection with the popliteal vein but not with the internal iliac vein, both variant veins were denominated as "lower type persistent sciatic vein". Such a variation would be important with respect to the risk of complication during popliteal sciatic nerve blockade.