Vasovasostomy: kinetics and predictors of patency.

Objective: To assess the timing of patency and late failure (secondary azoospermia) after vasovasostomy (VV) using standardized kinetics definitions.

Design: Retrospective cohort study.

Setting: University-affiliated hospital.

Patient(s): Patients with obstructive azoospermia.

Intervention(s): Vasovasostomy.

Main Outcome Measure(s): Univariate and multivariate logistic regression assessed predictors of patency and late failure. Patency was defined as any sperm return to the ejaculate; and >2 million total motile sperm (TMS) in ejaculate. Late failure after VV was defined as azoospermia; or <2 million TMS in ejaculate.

Result(s): 429 men underwent VV, with median follow up of 242 days. Mean time to patency was 3.25 months versus 5.29 months in the "any sperm" versus ">2 million TMS" groups. Finding sperm intraoperatively during VV significantly improved patency rates in multivariable analysis (odds ratio [OR] 4.22). This association was further boosted when sperm was found bilaterally (OR 6.70). Late failure rate (azoospermia) was 10.6% at mean time of 14.1 months and 23% for <2 million, at mean time of 15.7 months. When assessing predictors of late failure, intraoperative motile sperm bilaterally was a statistically significant protective factor on multivariate analysis (hazard ratio 0.22).

Conclusion(s): Vasovasostomy remains highly efficacious in treating obstructive azoospermia. Young patients, shorter obstructive intervals, and sperm identified intraoperatively predict improved outcomes. Clinicians can expect VV patency in 3 months and late failure within the first 2 years after surgery. However, patency rates, late failure rates, and kinetics vary by definition.