Is the timing of post-vasectomy seminal analysis important?

To review the practice in two hospitals with differing protocols in the timing of seminal analysis after vasectomy.

The results from 245 vasectomies carried out at Hospital A, where semen was assessed 3 months after vasectomy, were reviewed and compared with those from 100 consecutive vasectomies at Hospital B, where semen was assessed 6 months after vasectomy. The results of seminal analysis at Hospital A were also audited after changing to the 6-month protocol. The patients' preferences for the timing of seminal analysis were also obtained.

Of the 245 patients at Hospital A, 58 (24%) failed to provide samples, leaving 187 (76%) for evaluation; 528 samples were examined (mean 2.8 per patient, range 1-13). The first sample was positive in 36 (19.3%) and the second positive in 10 (5.3%), the first being negative. Four (2%) patients had persistent spermatozoa at 6 months, one subsequently undergoing exploration. Thirty-one (17%) patients provided further samples despite providing two consecutive clear ones. At Hospital B, 24 (24%) patients failed to provide samples; 10 (13%) patients had persistent spermatozoa at 6 months and live spermatozoa were detected in one patient's samples. All eventually produced clear samples, with none requiring exploration. After changing the protocol, 87 vasectomies were performed, with 18 (21%) patients failing to provide samples; seven (10%) of the samples collected showed occasional nonmotile spermatozoa at 6 months in either the first, second or both samples, with all samples clear by 8 months after vasectomy.

The complete disappearance of spermatozoa after vasectomy takes longer than is generally believed and we therefore suggest that given adequate counselling, seminal analysis 6 months after vasectomy is cost-effective and in the patient's interest.