How Likely Is Pregnancy After Vasectomy?

Medically Reviewed on 8/26/2021

What is a vasectomy?

Despite having a very high success rate, there are still times when vasectomies fail.  This is a rare situation. Less than 1% of vasectomies fail and result in pregnancies.
Despite having a very high success rate, there are still times when vasectomies fail. This is a rare situation. Less than 1% of vasectomies fail and result in pregnancies.

Vasectomy is one of the most effective forms of contraception. It’s a minor operation that cuts off the pathway between the penis and the testicles. After a vasectomy, sperm can no longer make their way from the testicles to the penis as part of an ejaculation. Without sperm, you can’t impregnate your partner. 

Despite having a very high success rate, there are still times when vasectomies fail.  This is a rare situation. Less than 1% of vasectomies fail and result in pregnancies. There is usually no way to tell if your vasectomy has failed until your partner gets pregnant unexpectedly. This doesn’t happen often, so it’s very surprising and confusing when it does.

A vasectomy is an operation to prevent sperm from leaving the body. During a vasectomy, your doctor makes a small incision in your scrotum. They will then cut the vas deferens, which is the tube that carries sperm from the testicles to the penis. The doctor will remove part of the tube and seal the ends. After that, there is no longer a way for sperm to leave your testicles.

You still produce live sperm in your testicles after a vasectomy. The sperm cannot leave the body during ejaculation. Your orgasms will still contain fluid, but no sperm will be present.

Having sex too soon

Sometimes pregnancies happen right after a vasectomy. This is because vasectomies aren’t effective immediately. When you have your vasectomy, the sperm already in the position to be ejaculated can live for many weeks. You could ejaculate live sperm and cause a pregnancy during that time.

Typically, your doctor will schedule a follow-up appointment 90 days after your vasectomy to check for any remaining sperm. If there are no sperm in your semen sample, the vasectomy is considered successful. If there are living sperm, your doctor will have you come back a few weeks later to check again. In many cases, all remaining sperm are gone by the second follow-up visit. 

Early recanalization

In rare cases, vasectomies reverse themselves. The separated ends of the vas deferens can reconnect inside your body. The scar tissue at each end can join with the other cut tube and create a link. If there are open channels in the scar tissue, sperm can get through them, and you will ejaculate them.

This is most common within the first three months after a vasectomy. In some cases, the scar tissue will close over time and block sperm completely. In the meantime, you will need another form of contraception to prevent pregnancy. Your doctor can do a repeat vasectomy to correct the issue.

Medical error

Sometimes a vasectomy fails because the doctor didn’t sufficiently separate the tubes. If the surgeon doesn’t remove enough tissue from the vas deferens, the two ends can reconnect. This is more likely to happen if the doctor didn’t properly seal each end of the tube.

‌When this happens, doctors can usually spot the problem when you have your follow-up appointment. There will be live sperm in your sample, so the doctor will examine you to see if there is a problem. If they discover that the tubes have reconnected, they can repeat the vasectomy.

Late vasectomy failure

It’s very rare for vasectomies to fail over the long term. Experts estimate that the failure rate is between 0.04–0.08%, or approximately 1 in 2000 cases. The way most failures are detected is from an unplanned pregnancy.

Experts have found that it’s possible for very small numbers of sperm to appear in semen even after a vasectomy. This may be due to how complex the anatomy of the testicles is. There are a lot of spaces where sperm can linger long after the vasectomy is performed. Small numbers of sperm may also be able to detour through different parts of the testicles.

In other cases, the tubes inside your body may recanalize over time. That reopens a pathway for sperm to leave your body. When this happens, you will need a repeat vasectomy.

Vasectomy reversal

Most vasectomies are reversible. Your doctor can reattach the ends of the vas deferens so that you can ejaculate sperm again. Once you do this, you may be able to impregnate your partner.

The success of the reversal depends on how long it has been since you had the vasectomy. If the original operation was 10 years ago or less, there is a 75% chance of success. The success rate goes down the longer it has been since the vasectomy.

A successful vasectomy reversal doesn’t guarantee a pregnancy. There are a lot of factors that affect whether a couple can conceive. You can discuss this with your doctor if you have questions.


The first sign of pregnancy is most often: See Answer

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Medically Reviewed on 8/26/2021
Arizona Urology: “What is the Success Rate for a Vasectomy Reversal?”

Canadian Urology Association Journal: “CUA guideline: Vasectomy.”

Indian Journal of Urology: “Vasectomy: A simple snip?”

The Lancet: “How reliable is a vasectomy? Long-term follow-up of vasectomised men.”