An Analysis of Major Causes of Surgical Failure Using Bähren System in Intraoperative Venography During Varicocelectomy.

Remnant collateral veins of the internal spermatic vein (ISV) (Bahren type 3) are the most common cause of failure in ASV. In a few patients, an external spermatic vein merges with the ISV at a higher level (Bahren type 4) and is unidentifiable without venography.