When a man considers a vasectomy he may think that it cannot be undone, and thus irreversible. But in reality, a vasectomy can be undone with great care and understanding. When a vasectomy is undone it is called a “vasectomy reversal.”
However, whether or not it will work well enough to return adequate sperm to the semen will not be known for some time after the procedure, and there is no guarantee that it will work.
There are a couple of factors that determine the likelihood of a successful vasectomy reversal:
The length of time that has past since the vasectomy
How the surgeon does the repair
How well the vasectomy heals
Presence of anti-sperm antibodies and assorted anatomic signs at surgery
The longer the time since the vasectomy, the lower the chance of success. If it has been less than three years since the vasectomy, the sperm returns 97% of the time and there is a 76% chance of pregnancy. (The percent chance of sperm return and pregnancy are not the same because there are many other factors that go into pregnancy.) On the other hand, if it has been more than 15 years, the sperm returns only 76% of the time and there is only a 30% chance of pregnancy.
For the repair, there are one-layer and two-layer repairs of the vas deferens. In almost all studies, the two layer repair, done with a microscope, gives the best result. The inner layer of the vas is reattached first, making the tube aligned properly in the center of the vas deferens. The outer layer reinforces the first.
If anti-sperm antibodies are present as a result of the body dissolving sperm trapped by the vasectomy then the sperm after vasectomy reversal are at risk of being attacked by the immune system and may not be able to do their job well for pregnancy.
This is one reason the pregnancy rate is lower. Sperm granulomas and other signs of the fluid in the vas deferens at surgery can suggest positive or negative outcomes as well, but these only are seen during surgery and can’t help you make the decision to get a reversal.
In general, vasectomy is hard to undo. Done right it requires a microscopic two-layer technique in the hands of the most experienced Urologist. But keep in mind that vasectomy reversal is not covered by insurance, so it will require that the entire surgery be paid for up front. And while there is no guarantee of success, many men have reversals and go on to father many more children afterwards.