Vasectomy is a surgical proceure in which the vasa deferentia of a man are cut for the purpose of sterilization. There are some variations on the procedure such as no-scalpel (keyhole) vasectomies, in which a surgical hook, rather than a scalpel, is used to enter the scrotum. Another type of vasectomy which may reduce the risk of chronic pain could be the so-called "open ended" vasectomy. A "normal" vasectomy typically seals both ends of the vas deferens with stitches, heat, or both, after cutting. The open-ended vasectomy seals only the top end of the vas. With this method sperm are free to spill out from the lower severed end of the vas thus avoiding any build-up of pressure. The likelihood of long-term testicular pain from "backup pressure" seems to be eliminated using this method.