One azoospermic sample enough after vasectomy to confirm future sterility

April 1, 2008

Data from studies on post-vasectomy clearance suggest that a single azoospermic sample submitted 16 weeks following vasectomy is sufficient to establish the success of the procedure and future sterility.

"Vasectomy failure can have significant legal implications, so counseling is appropriate for all patients," said Whipps Cross urologist Simon Holden, FRCS, speaking at the AUA annual meeting in Anaheim, CA. "Provided patients are adequately counseled, one sample is sufficient to document vasectomy success if it is submitted at about 4 months post procedure."

Some studies have explored semen samples submitted as early as 6 weeks after vasectomy, Dr. Holden explained. The shorter waiting period is less effective because recanalization may not be complete 6 weeks after the procedure. The literature shows that 12 weeks is an adequate waiting period.

Vasectomy is one of the most common forms of sterilization, with more than 42 million couples worldwide opting for this relatively simple outpatient procedure. Vasectomy is also one of the most effective methods of birth control, with failure rates of less than 1% consistently reported from study sites around the globe.

Vasectomy isn't perfect

The problem, Dr. Holden continued, is that vasectomy is not perfect. Sterility cannot be absolutely guaranteed even following two azoospermic samples, which is the current standard of care.

A literature survey of Medline, Embase, and Cochrane databases led by Tim Philp, MChir, consultant urologist at Whipps Cross, found that between 0.6% and 2.4% of vasectomy patients show transient sperm in post-vasectomy samples. At least one study in the current literature reported the presence of sperm in 10% of men scheduled for vasectomy reversal. Multiple reports have documented DNA-proven fatherhood by men who have undergone vasectomy and who have provided two consecutive azoospermic post-vasectomy semen samples.

There is also continuing controversy over the clinical significance of rare non-motile sperm that have been observed in a minority of vasectomy patients. Some urologists see little risk of pregnancy from non-motile sperm, while other clinicians are reluctant to release vasectomy patients who show any sign of sperm.

"This is an extremely sensitive area," Dr. Holden told Urology Times. "People are very reluctant to change their practice without a general consensus."

The Whipps Cross literature survey may help move the general consensus. Of patients who show rare non-motile sperm following vasectomy, 96% are azoospermic within 6 months of the procedure, and 100% are azoospermic within 12 months of vasectomy. A select group of 350 men with persistent rare non-motile sperms who were given "special clearance" to engage in sex without using other forms of birth control resulted in no pregnancies whatsoever.

The conclusion is clear, Dr. Holden said. A single azoospermic sample about 16 weeks following vasectomy should be considered sufficient to establish sterility in practical terms, and the minority of patients who produce rare non-motile sperm following vasectomy should be considered azoospermic in practice.

Dr. Holden pointed out three significant advantages to a single sample protocol: It will significantly reduce the number of semen analyses performed, induce less frustration among patients and urologists, and decrease inconvenience to patients.