The term, technical success, refers to ability to restore the the vas deferens and epididymis to their normal, open state, as they were before your vasectomy, allowing the passage of sperm from the testes. This is determined by the appearance and number of sperm found in a sperm count (semen analysis) after surgery. Historically, the best technical success rates have been obtained when there is no obstruction in the epididymis, allowing a vas-to-vas (VV) repair on both sides at the site of the original vasectomy.
As time passes after a vasectomy, the likelihood of obstruction in the epididymis increases—especially after 7-10 years. However, some men, even 15 or 20 years after vasectomy, do not develop such obstruction, and may therefore expect the better technical success rates a vas-to-vas repair affords. The increasing incidence of secondary epididymal obstruction with time is the most important reason that technical success rates tend to decline as the time after vasectomy increases. With increasing time after vasectomy, the increased pressure from the vasectomy may result in rupture and internal leakage of sperm in the epididymis, with resulting inflammation, scarring and blockage. This may occur on either side, or both. The blockage is microscopic, causes no symptoms as a rule, and cannot be detected on a physical examination before surgery. It can only be detected at the time of surgery. When epididymal blockage occurs, repair of the vasectomy site alone will fail—the vas must be connected to the epididymis directly, above the site of obstruction.
This procedure — called an epididymal repair or vasoepididymostomy (VE) — is one of the most technically demanding procedures in surgery, because of the exceedingly small and delicate nature of the epididymal tubule. It is a procedure which can only be performed successfully by a microsurgeon with extensive experience in such reconstructive surgery. Even in the hands of experienced microsurgeons, epididymal repair has a lower technical success rate than vas-to-vas repairs. This is due both to the extremely small size and fragile nature of the epididymal tubule, and because the obstruction sometimes occurs very close to the junction of the epididymis and testes, where it is very difficult to repair.
The goal for most patients undergoing reversal surgery is achieving pregnancy. Technical success—successfully reconstructing the duct system—is a prerequisite, of course. But not all men who undergo successful reversal surgery will be able to get their wives pregnant. The problem is reduced sperm quality due to alterations in the epididymis as a result of the original vasectomy.rnrnSperm normal spend about 6-8 weeks in the epididymis after they leave the testes, where they develop their fertility capability: the ability to swim—called motility—and the ability to penetrate and fertilize the egg (called capacitation). When a vasectomy is performed, the testes continues to manufacture sperm. These are released into the epididymis, where they will eventually break down and be reabsorbed. However, the increased pressure following vasectomy causes changes in the epididymal duct which affects the development of motility and capacitation. In general, the longer the time after vasectomy, the more pronounced these changes become.rnrnWhen a successful reversal is performed, sperm will be found in the seminal fluid in most cases within a short period of time. Sperm counts often rise to normal levels within months — although in some cases it can take quite a bit longer. However, in most men, the percentage of motile sperm remains very low at first, and may take a much longer time to recover. In some men, motility and capacitation remain poor permanently, preventing successful pregnancy.rnrnAs a result, pregnancy rates after reversal are lower than would be expected given the technical success rates, and tend to decline as the time after vasectomy increases.rnrnKeep in mind that there is does not appear to be any evidence for increased genetic abnormalities in sperm following vasectomy reversal — the incidence of miscarriage and birth defects following reversal are no different than that of the general population.rnrnYou may view the 25-year historical pregnancy rates for Dr. Finnerty”s patients here. Note that current techniques of epididymal reconstruction and understanding of the function of the epididymis in fertility are resulting in much greater success and fertility in recent years, and therefore these success rates are becoming somewhat dated.