A vasectomy is a surgical procedure that cuts or blocks the vas deferens, the two tubes that carry sperm from the testicles to the urethra. The procedure stops sperm from getting into the semen in order to prevent pregnancy.
After a vasectomy, an individual can still ejaculate and produce sperm, but the body reabsorbs the sperm, and it never reaches the semen.
A vasectomy is a very effective form of male birth control, but is it still possible for a partner to get pregnant?
In this article, we explore the reasons why pregnancy may still happen after a vasectomy.
We also look at the reversal options for achieving pregnancy and discuss sperm aspiration, a procedure that can lead to pregnancy if people use it with in vitro fertilization (IVF).
The likelihood of getting pregnant after a vasectomy is almost zero when couples wait at least 3 months following the procedure to have sex without birth control.
After a vasectomy, a doctor will test the semen to assess whether there are sperm present. To reduce the risk of pregnancy, the person who has the vasectomy and their partner should use a backup contraceptive method until a doctor gives them the go-ahead.
If people have sex without contraception too soon after a vasectomy, there is a risk that some sperm may remain in the semen. If so, this sperm could fertilize an egg, leading to pregnancy.
1. Having sex too soon
Vasectomy failures are most common in the months following surgery if a couple engages in sex too soon without using contraception.
The sperm life cycle is about 3 months. This means that sperm may be able to get into semen for several months following the procedure. The longer the time-lapse since the vasectomy, the less likely that this will happen.
Around 1–2 out of every 1,000 females whose partners have a vasectomy get pregnant in the year following the vasectomy.
2. Vasectomy procedure did not work
Sometimes the vasectomy procedure does not fully block the vas deferens. When this happens, a doctor might recommend redoing the procedure, sometimes using a different vasectomy method.
In most cases, a semen analysis that a doctor does after the procedure will reveal that it did not work.
It is also possible for a vasectomy to fail weeks, months, or even years after the procedure through a process called recanalization.
Recanalization happens when the vas deferens grow back to create a new connection, causing the vasectomy to reverse itself.
Most cases of recanalization happen within 12 weeks of the procedure. When recanalization happens years later, it may go undetected until a person's partner gets pregnant.
The risk of recanalization may increase if:
- a person chooses an open-ended vasectomy, which closes only one end of the vas deferens
- sperm tissue is present at the vasectomy site
Late failure is less common, with an estimated failure rate ranging from between 0.04 to 0.08%.
Most vasectomies are reversible.
The procedures for reversal are:
- Vasovasostomy: This procedure is where a doctor rejoins the cut or clipped ends of the vas deferens. This procedure is used in most cases and is less technically challenging, and therefore has higher success rates.
- Vasoepididymostomy: An alternative procedure, where a doctor joins one end of the vas deferens to the epididymis, the tube that stores sperm and transports it from the testes. This procedure is more technically challenging, and so has a lower success rate.
Reversal success in achieving pregnancy
A number of factors influence the success of a reversal in achieving pregnancy, including:
- experience and skill of the surgeon
- good sperm count of the individual
- overall health of both partners
- intercourse timing
- the woman's fertility
If the first reversal fails, a person may choose to pursue a second reversal.
IVF is a procedure that fertilizes an egg outside of the woman's body. A doctor then implants the egg into the woman's uterus in the hope of pregnancy occurring.
People who have had vasectomies can still impregnate their partners through IVF, even without a vasectomy reversal.
To achieve this, a person undergoes a sperm aspiration under anesthetic. During this procedure, a doctor directly retrieves sperm from the testis or epididymis using a needle.
As long as a person's sperm are healthy at the time of sperm aspiration, their chances of impregnating their partner through IVF are the same as they would be if they had not had a vasectomy. So, for people whose partners have fertility issues or who are not good candidates for reversal, sperm aspiration may be the best option for having a child.
People with concerns about overall success rates or who believe they may wish to reverse their vasectomies should discuss all options before pursuing a vasectomy.
There is no guarantee that a vasectomy will work in all people, nor that a vasectomy reversal will make a person fertile. People should, therefore, weigh the risks and benefits with their partners and doctors.