Vasectomy is one of the most popular forms of birth control worldwide. The simplicity, safety and durability of the surgical procedure make it an attractive option both for patients and doctors. However vasectomy failure is also reported.
Most experts cite the vasectomy failure rate to be one in 2000 cases. Vasectomy failure rate is thus less than 0.1% and is better than the 1.85% failure rate in the case of female tubal ligation.
Vasectomy failure is divided into two categories: early and late. Early vasectomy failure occurs within first few months after a vasectomy. It can be attributed to unprotected intercourse before attaining a negative semen analysis confirming sperm count to be zero. This happens because some living sperm may not have been flushed out from the system after the vasectomy procedure. Usually it entails around 20-25 ejaculations or 3 months for the downstream, living sperm to be completely flushed out of the vas deferens after a vasectomy.
Indulging in unprotected sex during this period may result in unwanted pregnancy. This failure can be avoided by using contraception till semen analysis after 3 months confirms azoospermia or zero sperm count.
Another cause of early vasectomy failure includes the inadvertent missing of a vas during the procedure. This might happen if the doctor excises two portions of the same vas or if he ligates a section other than the vas.
The other type of vasectomy failure is late vasectomy failure and is mostly caused by recanalisation of the vas deferens. This results in blocked tubes reconnecting after the procedure either on one side or both sides. The frequency of this happening depends on how the surgeon made the blockages in the vas deferens in the first place.
Sperms are highly mobile and when they face the blockages achieved by the vasectomy they try to penetrate that barrier too. In the early stages of vasectomy the scar tissue that consists of the blockage may be soft and easily penetrated by the sperm as compared to the scar tissue that may harden after several months. During this delicate stage especially within 4 months of the vasectomy, the vas deferens ends might not be reconnected but the tender scar tissue in between them become covered with holes and resembles a Swiss cheese. Here the sperm escapes to the other side as many passage ways are created for the sperm to move to the other side.
The sperm count at this stage stops falling, remains constant and after a while, even rises. Recanalisation rates can be lowered by techniques such as utilizing non absorbable sutures or surgical clips, fascial interposition (placing each severed end of the vas deferens away from each other) and cauterization (burning of inner hole of the tubes). The doctor may combine more than one method to achieve a higher success rate. Some experts estimate recanalisation rates to be 1 in 1500.
Vasectomy failure can also be due to wrong identification of sperm tubes during the vasectomy and not being able to block both sides of the vas deferens. Other than the vas deferens, there are blood vessels and nerves in the scrotum. If the surgeon severs any part other than the vas deferens, sperms flow will continue. This results in normal sperm count in the semen even after the vasectomy. It is important to use the services of an experienced surgeon to avoid this predicament.
Conclusion: Vasectomy failure can occur in early and late phases. While early failure is mainly due to unprotected intercourse before ascertaining zero sperm count, late failure is mainly due to tubal recanalisation.