Determining the success of vasectomy

To examine patient compliance, significance of rare nonmotile sperm (RNMS) and to determine the timing and number of semen analyses required to confirm sterility.

From November 2001 to November 2004, 436 consecutive primary vasectomies were performed by one surgeon. All patients were instructed to submit two initial semen specimens for analysis (2 and 3 months after vasectomy) and additional samples (at 1-month intervals) if sperm were identified on the initial and subsequent analyses.

A quarter of the patients submitted no semen specimens and only 21% followed the full instructions to provide two consecutive negative semen analyses. Three-quarters of the patients provided a semen specimen at 8 weeks after vasectomy; of these, 75% were azoospermic and 25% contained sperm. At 12 weeks after vasectomy half the patients provided a semen specimen; of these, 91% were azoospermic and 9% contained sperm. Of the 83 patients with semen containing sperm at 8 weeks, 80 had RNMS and three had rare motile sperm (one of whom subsequently proved to have vasectomy failure). Of the 80 patients with RNMS, at 3, 4, 5, 6, 8, 10 and 11 months, 65, four, three, four, two, one and one, respectively were azoospermic.

The present results indicate that many patients are not compliant with the protocol after vasectomy. Provided patients have been adequately counselled, we think that one negative semen analysis at 3 months or one with RNMS at 2 months may be adequate to determine the success of vasectomy. This should reduce the number of semen analyses, including reducing the number of men who must undergo repeat testing, without sacrificing the accuracy of determining paternity. Simplifying the follow-up after vasectomy is important; not only would it be cost-effective but it may also improve patient compliance.