Thirty-one studies (n>9,977,963, exact number unclear due to multiple comparisons and missing information) were included. Four were randomised controlled trials (n=2,136) and four were non-randomised trials or quasi-randomised controlled trials (n>2,878, exact number unclear due to multiple comparisons); the other studies (n>9,972,949, exact number unclear due to multiple comparisons and missing information) were case series with historical or concurrent controls, cohort studies, before-and-after studies, or of unspecified design.
Overall, the methodological quality of the studies was low. Agreement between the two reviewers was high (kappa 0.80, 95% confidence interval: 0.67, 0.83).
Five studies showed in at least one dataset that fascial interposition increases the occlusive effectiveness of ligation and excision; only one of these reported a statistically significant difference.
Eleven studies investigated cautery of the vas lumen; seven showed better results for cautery versus ligation in at least one dataset.
Of the nine studies evaluating vas isolation, five reported fewer total complications, five reported fewer bleeding or haematoma, and six reported fewer infections with the no-scalpel vasectomy approach compared with incisional techniques. However, not all of the comparisons were statistically significant.
Numerous other results were reported in the review.