Vasectomy success rates
Vasectomy is successful in more than 99 percent of men. Other methods of contraception are required until a semen analysis confirms there are no sperm in the semen.
The sperm count is checked approximately three months after the procedure. A man needs to have had at least 20 ejaculations after vasectomy to clear the ducts of sperm.
A sperm count requires that the man give a semen sample obtained by masturbation. When sperm remains present a repeat semen test is required.
If the semen analysis shows sperm that do not move there is a small chance that a pregnancy may occur. Other methods of contraception should be continued until a clear test result is completed