Vasectomy reversal success rates are generally reported in two ways: technical success rates and pregnancy rates. When evaluating success rates, you should keep in mind that they are statistical averages of large numbers of patients. Your specific situation and results may differ from that of a group because of many personal variables, such as your age, your fertility prior to vasectomy, your partner's fertility, the technique of vasectomy, and a host of other factors. Their principal value is to guide you to a general idea of your chances for success.
There have been many medical studies evaluating the success rates of vasectomy reversal, and these studies are often quoted by reversal surgeons when you ask about your chances for successful reversal. Unfortunately, these studies provide little or no help in assessing your chances for success with a specific surgeon. A surgeon with limited experience in microsurgery will rarely if ever achieve the quoted success rates.
Whenever possible, you should try to determine the experience and personal success rates of the specific surgeon to whom you are entrusting your reversal.
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.
In general, the best technical success rates are obtained when there is no obstruction in the epididymis, allowing a vas-to-vas 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. However, not all men who are over ten years develop such obstruction, and may therefore expect the better technical success rates a vas-to-vas repair affords.
Recent experience has shown many men originally thought to be at low risk for epididymal obstruction--thos five years out or less--do in fact have such obstruction. Failure to identify this obstruction and address it at the time of surgery will lead to lower overall success rates.
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 on both sides. 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—is one of the most technically demanding procedures in all of 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 traditionally had a lower technical success rate than vas-to-vas repairs—often no more than 30-50% success. 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.
However, advances in technique with epididymal repairs now afford a success rate which approaches that of less complex, vas-to-vas procedures. Dr Finnerty has one of the largest experiences with epididymal reconstruction in the country, and recent experience has shown success rates on epididymal repairs approaching 80-85%—often with excellent postoperative sperm quality and good pregnancy rates.
You may view the technical success rates for Dr. Finnerty's patients here. Please note that these are historical figures going back over 20 years, and that recent success rates are substantially more optimistic in many cases.
The goal for most patients undergoing reversal surgery is acheiving 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.
Sperm normal spend about 6-8 weeks in the epididymis after they leave the testes, where they develop 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.
When 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.
As 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.
Keep in mind that there is no evidence for increased genetic abnormalities in sperm following vasectomy reversal—the incidence of miscarriage and birth defects following reversal is no different than that of the general population.
You may view the pregancy rates for Dr. Finnerty's patients here.