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J Urol. 2003 Sep;170(3):892-6.

A prospective study of time and number of ejaculations to azoospermia after vasectomy by ligation and excision.

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EngenderHealth, New York, NY, USA.



We obtained detailed information on the time and number of ejaculations to azoospermia after vasectomy by ligation and excision.


Men seeking vasectomy at 3 public clinics in Mexico City were invited to participate in this prospective noncomparative study. Vasectomy was performed using the no-scalpel technique. The vas was occluded using 2 silk sutures and the segment of vas between the ligatures was excised. Men were followed biweekly up to 24 weeks after vasectomy or until azoospermia was confirmed. Semen was examined at each visit for sperm concentration and motility. The main outcome measure was azoospermia in uncentrifuged semen samples.


The life table rate for time to azoospermia was 81.5/100 men (95% CI 76.2 to 86.9) by the end of the study. Cumulative Kaplan-Meier event probability attained a maximum of 79.5/100 men (95% CI 73.7 to 85.2) at 70 ejaculations. Only 60/100 and 27.9/100 men were azoospermic by 12 weeks and 20 ejaculations, respectively. These end points are the commonly recommended waiting periods when semen analysis is unavailable. Of the 217 men 36 (16.6%) did not achieve azoospermia by 24 weeks, of whom 25 (11.5% of all participants) were considered to have vasectomy failure.


Our results suggest that it is not possible to develop guidelines for clearance based only on the time or number of ejaculations when ligation and excision are performed. In addition, of the methods for vas occlusion during vasectomy ligation and excision may not provide the best success rates.

[Indexed for MEDLINE]

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