Vasectomy Failure Rate
According to WebMD, 1 in 100 vasectomies fail within 5 years of the vasectomy procedure. In order to minimize the risk, patients are strongly encouraged to follow the doctor's recommendation to collect and send in two negative semen specimen samples within 16 weeks of the vasectomy procedure. Other forms of contraception should be used to avoid pregnancy until a confirmation is received that there is no motile sperm in semen. Additionally, the vas deferens, which were cut during your vasectomy, may regrow (late recanalization). This can result in vasectomy failure years after the procedure.
Post Vasectomy Semen Analysis Tests
The post-vasectomy semen analysis test is done to determine the presence of sperm after the procedure. In order for a vasectomy procedure to be deemed successful, the patient needs to receive a confirmation that there is an absence of sperm in your semen. A study published by Androl Gyneco shows a 42% compliance rate for post-vasectomy semen analysis tests.
In order for a semen collection to remain viable through the mail, a formalin fluid is used to preserve and immobilize the sperm. Double Helix Research suggests that "the best quality sperm are obtained when the specimen is collected after three days of sexual abstinence, but not more than five to seven days." The sperm counting method is performed by looking at the specimen under 40 high power microscopic fields.