There are three main reasons for this:
- Surgery restores sperm cells to the semen but the sperm may be weak or low in number
- Good numbers of strong sperm are found after surgery but “antibodies” that attack sperm may be present
- There are unanticipated problems with the fertility of the female partner
There are two important points to make about the “success” table:
- The pregnancy rates reflect the results of sexual intercourse at home. The advanced fertility treatments in the laboratory (in vitro) can be used when the surgery results in weak sperm or low numbers of sperm. These techniques can increase the pregnancy rates for those unable to conceive after a reversal.
- If epididymal obstruction is not recognized and corrected at the time of the reversal, the success rates will be lower.
Let’s discuss this last point in more detail. We know that certain findings at the time of the vasectomy reversal will give us more information about the chances of success. When the reversal is done, the vas deferens is cut between the testis and the vasectomy site. The fluid that comes out of the vas deferens can be examined with a microscope in the operating room (Figure 3).
Thick fluid without sperm is almost always a sign that the delicate tubes on the side of the testis (called the epididymis) have become blocked. It is possible to bypass the epididymal block by performing a vasoepididymostomy (don’t try to pronounce this word!).
A vasoepididymostomy is a surgical procedure in which the vas deferens is hooked up directly to the epididymis above the blockage (Figure 4). Generally, the success rate of vasoepididymostomy (as defined by sperm in the ejaculate after surgery) is about 75-80 percent. This is very significant compared with the 10 percent rate of success following a standard vasectomy reversal when the fluid is thick and devoid of sperm.
So keep in mind that the success rates in the table above will be higher if the surgeon is prepared to perform a vasoepididymostomy if an epididymal block (thick fluid) is suspected at surgery. We will attempt to identify cases with epididymal obstruction. (See next question).
One final point: The fluid findings at surgery may be equivocal for epididymal blockage. For example, the fluid may be thick but nonetheless contain sperm or sperm fragments. Alternatively, the fluid may be thin or scant but may not contain sperm or sperm fragments. In these cases, it is not clear if the epididymis is blocked or not. Your doctor will weigh all of the relevant factors and perform the type of connection with the highest chance of success. In some cases, it may be necessary to perform the delicate vasoepididymostomy on one side and the “standard” vasectomy reversal on the other.