Measuring the success of a vasectomy reversal

When potential patients begin doing research on vasectomy reversals, it’s inevitable that success rates will be one of the main concerns that needs to be addressed. What’s clear, though, is that success rates can be impacted by many factors. The following discussion lists some important information to consider.

One way to answer the question, “what are success rates” is to start with the main factors which define success.

There are at least four key factors which contribute to ‘success rates’ with vasectomy reversals:

Semen parameters
Based on two scientific publications (Majzoub 2017; Silber 2013), success could be defined as having 5 million sperm per milliliter post-reversal. This is because men who achieved 5 million or more sperm had similar pregnancy rates (about 60%) compared to men who had at least 15 million, or even higher numbers. However, men who had below 5 million sperm per milliliter were about 4x less likely to achieve a pregnancy (about 15% pregnancy rates).

Motility can also be used to help predict the success with pregnancy, with men who had 10-40% motility achieving pregnancies in 63% of cases vs 77% among those with motility over 40%. In contrast, those with motility below 10% achieved pregnancies in 21% of cases. Other factors have also been reported, including morphology and total motile sperm counts per ejaculate. Unfortunately, no one single measure is perfect in predicting pregnancy. And sperm counts and motility can fluctuate significantly, even when the same sample is examined repeatedly by the same lab technician! So, in comparing success rates, it is important to look at how ‘success’ is specifically defined. If the definition is ‘patency’ then this typically means that the surgeon saw one sperm at any time post reversal. This likely is too loose of a definition. Similarly, it is important to recognize that many practices will report the ‘max’ number of sperm seen at any time point.

Type of procedure
This one is a bit harder to predict, because the main concern is something that isn’t apparent before surgery. There are two types of repairs which can be performed at the time of a vasectomy reversal: vasovasostomies (i.e. simple repairs) and epididymovasostomies (i.e. complex repairs). The problem is, it is not possible to know which procedure you will need until you are part way into surgery. In our experience, 8% of men will need a complex repair on both sides, while 22% of men will require a complex repair on one side. Because of this, if you elect to do a surgery where the surgeon is only able to do simple repairs, in 22% of cases, your outcomes will be lower than they would otherwise be if your surgeon could do complex repairs. And in 8% of cases, the repair would be a failure at the time of surgery.

When comparing rates, it is important to look at whether “all-comer” rates are being reported. If the team is only reporting results from “vasovasostomies only,” for example, this will inflate the rates. Similarly, if the surgical team only performs vasectomy reversals on men who are less than 5 years out from their vasectomy, the success rates and pregnancy rates will be higher compared to a practice which accepts men regardless of time since vasectomy.

The time since the vasectomy was performed
The longer it has been since the vasectomy, the more likely that you will need a complex repair. However, it is important to recognize that the time since reversal is not a perfect predictor. In reviewing our data, the time since vasectomy is able to predict about 15% whether or not a complex repair will be required. However, the time since vasectomy also reduces the likelihood for total sperm counts and pregnancy rates, independent of whether a complex repair is performed or not. The time since vasectomy is not a guarantee for success or failure, as we have seen cases of men who are less than 1 year out failing (both ours and other surgeons) and have cases where men over 30 years out are able to achieve pregnancies.

The type of technique also matters here, as our data showed that the use of ReVas as a technique made the time difference no longer a key factor in determining whether sperm returns post repair or not. As noted earlier, when comparing success rates, if the practice only operates on men who are less than 5 years out from reversal, for example, their rates will likely look better than ones which operate on men who are 10, 20, or 30+ years out from reversal. This is an important point to consider when comparing surgical practice outcomes.

Your partner’s age and fertility status
It’s important to note that female fertility and your baseline fertility are also key factors. It’s considered that women begin to decline in fertility at age 35. Also, about 15% of couples are unable to achieve a pregnancy, even with no prior vasectomy as a factor. For this reason, pregnancy often isn’t used as a definition for success post reversal (after all, if someone achieves a return of sperm post reversal, but the partner has factors which make her infertile, it’s not possible to truly assess whether that couple could have achieved a pregnancy together). This is an important factor to recognize, as many couples will interpret “success” as being pregnancy, which is not accurate.


As with any surgical procedure, knowing benchmarks early and having appropriate expectations is important, both with providing peace of mind as well as a measurement for success. You can learn more about reversals, from success rates to techniques to costs, at our website.

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