Vasectomy and vasovasostomy. II. A comparison of two methods of vasovasostomy: silastic versus chromic stents.

Twelve adult, bilaterally vasectomized dogs were used to compare two different procedures for reuniting the severed vas deferens. Approximately 5 months postvasectomy six dogs had vasovasostomies utilizing Silastic stents and the vasa deferentia of six additional dogs were rejoined with intravasal chromic stents. Ejaculates were subsequently obtained at 2-week intervals and evaluated for sperm count, motility, viability, and seminal ion concentrations. All of the dogs in which Silastic had been utilized as the stent had sperm reappear in the ejaculate, whereas only 40% of the dogs in which chromic catgut had been utilized had reappearance of spermatozoa. The over-all quality of the ejaculate was also better in the animals in which Silastic had been utilized. Testicular and epididymal histology was normal in most dogs of both groups, but three of the dogs with chromic stents in which the anastomosis had not been a success had abnormal histology, with reduced numbers of spermatocytes, spermatids, and spermatozoa. The data suggest that Silastic stents are better than chromic stents for vas reanastomosis. They also suggest that some dog testes react negatively to vasectomy and do not recover by 1 year postvasectomy when vas patency is not reversed.