Objective To review the practice in two hospitals with differing proto
cols in the timing of seminal analysis after vasectomy, Patients and m
ethods The results from 245 vasectomies carried out at Hospital A, whe
re semen was assessed 3 months after vasectomy, were reviewed and comp
ared with those from 100 consecutive vasectomies at Hospital B, where
semen was assessed 6 months after vasectomy, The results of seminal an
alysis at Hospital A were also audited after changing to the 6-month p
rotocol, The patients' preferences for the timing of seminal analysis
were also obtained, Results Of the 245 patients at Hospital A, 58 (24%
) failed to provide samples, leaving 187 (76%) for evaluation; 528 sam
ples were examined (mean 2.8 per patient, range 1-13), The first sampl
e was positive in 36 (19.3%) and the second positive in 10 (5.3%), the
first being negative, Four (2%) patients had persistent spermatozoa a
t 6 months, one subsequently undergoing exploration, Thirty-one (17%)
patients provided further samples despite providing two consecutive cl
ear ones, At Hospital B, 24 (24%) patients failed to provide samples;
10 (13%) patients had persistent spermatozoa at 6 months and live sper
matozoa were detected in one patient's samples, All eventually produce
d clear samples, with none requiring exploration. After changing the p
rotocol, 87 vasectomies were performed, with 18 (21%) patients failing
to provide samples; seven (10%) of the samples collected showed occas
ional nonmotile spermatozoa at 6 months in either the first, second or
both samples, with all samples clear by 8 months after vasectomy. Con
clusions The complete disappearance of spermatozoa after vasectomy tak
es longer than is generally believed and we therefore suggest that giv
en adequate counselling, seminal analysis 6 months after vasectomy is
cost-effective and in the patient's interest.