During vasectomy consultations, I hear a number of concerns from men. Often, they want to know if the procedure is reliable. Many share stories of couples they know who got pregnant despite a vasectomy.

One of the most significant pros of a vasectomy is that a vasectomy is a very effective and permanent form of birth control. Only one to two in 1,000 men have a vasectomy that fails. This usually happens in the first year following the procedure.

While failures are very rare, I have seen them happen. Here are three main reasons why:

  1. Sex too soon Most often, I find a procedure fails when a couple has sex too soon after surgery. It takes several months for semen to be sperm-free after a vasectomy and the only way to know is to have your semen tested. Until then, you can still get your partner pregnant.That’s why I tell my patients that they must use another method of birth control until they have a semen sample tested and it shows a zero sperm count. Better safe than surprised by an unwanted pregnancy.
  2. Snipped tubes reconnect Rarely, we see one of the vas deferens reattach on its own. (These are the two small tubes that transport sperm from the testicles out through the penis.) Small channels can form in scar tissue and allow sperm to wiggle through.This can happen at any point following the procedure, but it is more likely to occur sooner rather than later. I have yet to see it occur with one of my patients, but that doesn’t make it impossible.
  3. Surgical error Even rarer are surgical errors. While the procedure is very simple and performed in office, errors can occur. During a vasectomy, I remove a small segment of the vas deferens and the rest is “sealed.” However, if the tube is missed (most doctors will know if it has been), the procedure will not work. Having an anatomical variation or having had a previous surgery in this area of your body can increase the risk of this happening.

Vasectomy failure is extremely rare. And, in most cases, it’s avoidable. The best thing you can do to prevent an unwanted pregnancy is to use another method of birth control until the first semen sample.

Learn more about our vasectomies and clinics that perform the procedure at HealthPartners & Park Nicollet Urology