A Cochrane review included 6 studies with different comparison designs and with a total of 1 524 subjects. One high-quality, large multi-centre study (n=841) compared vasectomy (no-scalpel approach) + fascial interposition with vasectomy without fascial interposition (a technique in which one severed end of the vas is covered with the sheath tissues of the vas to enhance the barrier effect). The fascial interposition group was less likely to have vasectomy failure. Fascial interposition had more surgical difficulties, but the groups were similar in side effects.
Other studies were of poor quality and did not find any significant difference between the groups with respect to the primary outcome of time to azoospermia. One trial compared vas occlusion with clips versus a conventional vasectomy technique. Three trials examined vasectomy with vas irrigation, two comparing irrigation with water versus no irrigation, one compared irrigation with water versus the spermicide euflavine. Median number of ejaculations to azoospermia was lower in the euflavine group compared to the water irrigation group. One trial found that an intra-vas was less likely to produce azoospermia than was no-scalpel vasectomy. More men were satisfied with the intra-vas device, however.
Comment: The quality of evidence is downgraded by limitations in study quality.