Semen analysis after vasectomy: when and how many?

OBJECTIVE

To assess patient compliance for semen analysis after vasectomy, and to determine the timing and number of semen analyses required to confirm sterility.

PATIENTS AND METHODS

The study included 1321 men who underwent vasectomy between October 1995 and June 1998. They were followed up in two groups; in group 1 (one-test method) 961 consecutive patients were asked to provide a semen sample for analysis 4 months after vasectomy. Sterility was defined as the absence of sperm in one sample. If sperm were present in the sample, the test was repeated at monthly intervals until there were no sperm. In group 2 (two-test method) 360 consecutive patients were advised to provide semen samples 3 and 4 months after vasectomy. The absence of sperm in two consecutive samples was defined as the criterion to declare the man azoospermic. The presence of sperm in one sample required further samples every month until two consecutive azoospermic samples were produced.

RESULTS

In group 1, 810 patients provided semen samples, of which 783 (97%) had no sperm and the men were thus declared azoospermic. The remaining 27 (3%) samples contained sperm; six men withdrew from follow-up at various times but 21 patients produced a negative sample at some time within 7 months and were declared azoospermic. At the end of the follow-up, 804 (84%) patients had been declared azoospermic. In group 2, 294 (82%) patients provided a semen sample after 3 months but only 259 (72%) did so after 4 months. Of the patients providing the first sample, 287 (98%) were azoospermic, and after the second 252 (97%) were azoospermic. At the end of the follow-up 255 (71%) patients were declared azoospermic. There was no reported paternity in any of the men.

CONCLUSION

These results suggest that compliance was better in group 1; when the patients in group 2 were asked to provide a second sample the compliance decreased significantly. The percentage of patients producing an azoospermic sample was similar for semen provided after 3 and 4 months. Thus, provided that the patient is adequately warned about the risk of failure of the vasectomy at any time during his life, a single semen analysis after 3 months is sufficient grounds for discontinuing other contraceptive precautions.