They cut about a 1/4-1/2" length of tubing out of the vas deferens (the tubes that carry the sperm from your testes to the urethera). The method my doctor used was to cut about a 1/2" long hole in my sack, then pulled each tube out, cut, cauterized the ends and then tucked them back in. You can't just go right to sex without protection because there are usually sperm left in the tubes. It takes 20-30 ejaculations to clean out the tubes. For some reason, it took me about an extra month to get everything cleaned out. Guess I had some hangers on. lol.