Following Vasectomy, about half of the men who initially still have motile sperm will eventually stop producing sperm, according to a new study results reported in the journal Fertility and Sterility.

Motile sperm detected when the first semen analysis is conducted, about three months after vasectomy, “does not automatically mean that vasectomy has failed and that the procedure has to be repeated,” lead investigator Dr. Michel Labrecque told.

Labrecque of Hopital Saint-Francois d’Assise, Quebec City and colleagues note that the presence of motile sperm following the first post-vasectomy analysis is a cause for concern and it is often considered an indication for the need for a repeat procedure.

Depending on the surgical method used, they add, motile sperm is seen in anywhere from 0.3 percent to 13 percent of cases. The most common cause is reopening of the sperm duct.

To gain further information about how many men have a delayed in vasectomy success, the researchers examined medical records and surveyed 309 men who had had a first semen analysis that showed motile sperm.

In total, 174 men (56.3 percent) eventually had a successful Vasectomy outcome. Men who had a lower sperm count in the first analysis were more likely to eventually become infertile.

Another 113 men (36.6 percent) had repeated vasectomies. These were mainly due to similar or increasing numbers of motile sperm found in subsequent analyses or the persistence of motile sperm six months or longer after the original vasectomy.

Given these findings, the researchers conclude that, “the decision to repeat vasectomy should not rely on a single semen analysis showing motile sperm.”

SOURCE: Fertility and Sterility, May 2005.