Post-Vasectomy Semen Analysis

Should I do a post-vasectomy semen test?

Most physicians who do vasectomies would recommend at least one semen analysis after a vasectomy. It takes surprisingly long to clear the sperm from the walls of the vas tubes and from the seminal vesicles. It’s good to keep using contraception after the vasectomy for at least twelve weeks and then to do a semen test to confirm that you are in the clear.

What are the usual results of the post-vasectomy semen test?

There are three typical results – no sperm seen, rare sperm, and copious sperm.

What does it mean to have “rare sperm” in the post-vasectomy semen test?

Depending on the type of test done, around 20% of men will have “rare sperm” in the semen sample after 12 weeks. For the majority of men, this will simply clear itself up in a few weeks to a few months. The rare sperm in the sample are thought to be from a few “leftover” or residual sperm. These residual sperm calls can be retained in the seminal vesicles near the prostate or on the wall of the vas deferens. In other cases, as the healing cells form a scar over the ends of the vas tubes, the young scar can be soft and porous. The early scar can allow a few sperm cells to pass. Within a month or two after the first test, the scar usually solidifies and settles in to its final state of not allowing even the rare sperm to pass. So, if you are one of the men who have rare sperm in your post-vasectomy semen test, the next step is usually to wait a month, continue using some form of contraception, and repeat the sperm test. Your physician will chat with you about the next steps. With the modern method of vasectomy, only about 1 man per every 2,000 cases will need a repeat vasectomy. 

What does it mean to have “copious sperm” in the post-vasectomy semen test?

Sometimes a man will send in a sample very early after a vasectomy and there will still be many sperm seen by the lab. Very rarely, a significant passage will form between the ends of the tubes and this channel will allow sperm to pass freely. This is rare, but can happen. Usually, if you have a lab result of copious sperm in your sample, your physician will recommend that you continue using contraception, do a repeat test in a month, and decide on the best course of action from there. Years ago, when a vasectomy involved simply snipping the tubes, around 5% of men would have significant sperm present in the sample after a vasectomy. With the modern method of vasectomy, the vas tubes are snipped, cauterized, and tied apart. With the modern method of vasectomy, only about 1 man per every 2,000 cases (0.05%) will need a repeat procedure. 

If I have “no sperm seen” as my results after my vasectomy, should I do a second test?

After a vasectomy, we highly recommended getting a semen check after 12 weeks to make sure the you have achieved “vasectomy success.” After clearance by a reputable lab, most men feel very satisfied with their results. After achieving “azoospermia,” or “no sperm” in the semen, the chance of causing a pregnancy is very very low – around 1 in 2,000 or even less. Still, nothing is perfect. If the chance of a reconnection worries you, you can do another test. Some men do a repeat test every few years. The test is easy and inexpensive. You can choose whether you want to do repeat test, and how often. It’s up to you.