Vasectomy Success Rates
Vasectomy success rates are greater than 99%, and are no different between the conventional and the No Needle, No Scalpel techniques. However, it is important to note that, as with all methods of birth control, vasectomy failure and unplanned pregnancy can occur. Vasectomy failure can be described as early or late. Before elaborating on these, it would be helpful to explain the concept of recanalization.
Recanalization is the process of reuniting a divided channel of a bodily tube - in this case, the vas deferens. During vasectomy the vas deferens is divided, however even after vasectomy, the testes continue to produce live sperm. Vasectomy failure can occur because over time, your body may re-establish the connection between the divided ends of the vas deferens, thereby allowing live sperm to once again enter the semen.
Recanalization is described as early if it occurs during the first 12 weeks after the vasectomy. In this case, the 12 week semen analysis will detect the presence of live sperm. Because other contraception is still being used during this time, there is no increased risk of unplanned pregnancy due to early vasectomy failure - apart from the failure risk of the contraception method that you and your partner are using during this period. Early recanalization occurs in less than 1% of men who have had vasectomy. Repeat vasectomy would be necessary in these men.
It is important to note that the presence of sperm in the semen sample at 12 weeks does not usually mean that there is early recanalization. In most men, it simply means that more time is needed to clear the last of the sperm, and further semen analysis will be done at a later date to confirm this. If live sperm in the semen is detected on multiple subsequent semen analyses, then the diagnosis of early recanalization would be considered.
Recanalization is described as late if it occurs sometime after semen analysis has proven that the semen is free of sperm. In the case of late recanalization, the vas deferens re-establishes a path for sperm flow after an initially successful vasectomy. Late recanalization can occur months or even years after vasectomy. Because vasectomy success (no sperm in the 12 week semen sample) has been established and reported to the patient, other forms of back-up contraception have likely been discontinued, and unplanned pregnancy can occur. Late failure occurs in approximately 1 in 2500 men who have undergone vasectomy. It is important to note that the risk for unplanned pregnancy due to late failure is lower than the risk of failure due to any other method of birth control.