Vasectomy Success Rates

How Does a Vasectomy Fail?

1.) Unprotected Intercourse Right After Vasectomy

One way that they can fail is when a pregnancy occurs after a vasectomy is performed but before the remaining live sperm downstream from the vasectomy site are completely “flushed” out of the system. Typically, it takes 20-25 ejaculates (or 3 months of time) for the live, downstream sperm to be completely eliminated from the vas deferens tubes after a vasectomy.

Unprotected sex before this point could easily result in motile ejaculated sperm and pregnancy. This type of failure is easily avoided with proper patient education regarding the continued use of other forms of contraception until the ejaculate is “cleared” of sperm after the vasectomy.

2.) Recanalization Failure

Much less common are vasectomies that fail due to the blocked sperm tubes reconnecting on one or both sides after the procedure, also termed recanalization failure. The frequency of this depends mainly on how the blockage was made by the surgeon during the vasectomy procedure in the first place. Remember that sperm have a tail and move rapidly; their job it is to conquer unknown territories like the female reproductive tract. When hitting a blockage such as that induced by vasectomy, they try to penetrate it too. Early on after vasectomy, the scar tissue comprising the blockage is typically softer and may be more easily penetrated by live sperm than the same scar tissue after it had cross-linked and hardened several months later. During this period of susceptibility, usually within 4 months of the procedure, the ends of the vas deferens do not actually reconnect but the soft scar tissue between them becomes riddled with many small “holes” and takes on a “swiss cheese” appearance where sperm have driven through it to the other side. Thus, many tiny passages are created by the sperm to bypass the obstruction. This failure pattern typically presents as an appropriate, decreasing sperm count in the ejaculate after vasectomy that then stops falling and remains constant or even rises. Techniques such as the use of non-absorbable surgical clips or sutures, placing each end of the cut vas deferens away from each other (fascial interposition) or thorough burning (cautery) of the inner hole of the tubes are associated with the lowest recanalization rates. Combining two or more of these techniques may lower recanalization rates even more than the use of one approach alone. In Dr. Turek’s procedure, the recanalization rate is < 1/1500 cases.

3.) Inexperienced Surgeon

Lastly, vasectomies can also fail due to improper identification of the sperm tubes during the procedure and a failure to block both sides. The vas deferens tubes exist in the scrotum along with other structures including blood vessels and nerves. If something other than the vas deferens is selected for blockage, sperm will remain in the ejaculate. This results in a persistent, and often normal, sperm count in the ejaculate after the vasectomy. It is more likely to happen in cases of prior scrotal surgery that may obscure the anatomy, including surgery for undescended testis and prior vasectomy reversal. It can be avoided by choosing an experienced vasectomist (at least 250 cases worth) to do your procedure.