Pregnancy after vasectomy?

Are you getting a vasectomy?
Plan ahead and get some cold packs on Amazon and a 3 pack of jock straps for a comfortable post-surgery recovery!

Vasectomy is one of the most effective forms of birth control available, but pregnancy after vasectomy is possible.

We discuss how a woman can still become pregnant after a vasectomy in more detail below, but here are the most important things to know:

  1. There no way to be 100% certain a man is sterile (unable to conceive) until semen analysis has shown he has a zero sperm count.
  2. You must use alternate forms of contraception until laboratory tests confirm sperm is not present in the man’s semen.

If you follow these guidelines, the chances of conceiving after a vasectomy are extremely low, but it’s still important to understand the risks.

How is pregnancy after vasectomy possible?

There are three primary ways a pregnancy can occur after a vasectomy:

  • Having sex without contraception before the man’s sperm count is confirmed to be zero
  • Natural reversal, also known as recanalization
  • Surgical error

Sperm still present in semen (non-zero sperm count)

After a vasectomy, live sperm may still be present in a man’s semen for a number of months. This means that there is still a risk of impregnating a woman after the operation. Alternate contraception must be used until there is no sperm present (azoospermia).

Most doctors advise their patients that they should be sterile after two to three months and/or 20-25 ejaculations, but these are simply guidelines. It is still possible for a man to get a woman pregnant even if he is outside of these ranges. This is why doctors generally instruct their patients to have at least one semen analysis performed by a lab at some point after their operation. A sperm count is the only way to be certain a man is sterile.

When a pregnancy occurs after vasectomy due to unprotected intercourse before the “all clear” is given, it is known as a “technical error”. While most men understand that they can still get a woman pregnant immediately following their vasectomy, a surprisingly large portion of men (40% to 50%) don’t go back for a semen analysis.

Recanalization (spontaneous natural reversal)

A recanalization occurs when sperm are able to escape from the cut end of the vas deferens due to microscopic channels which have formed in the patient’s scar tissue. These tiny channels may be the result of a sperm granuloma or other complication. If these microchannels develop and the two severed ends of the vas deferens are very close or touching, sperm may be able to travel from one section of tube to the other.

Recanalization which occurs early on will be discovered as part of the post-vasectomy semen analysis and occurs in less than 1% of vasectomies. However, it is possible (but unlikely) for recanalization to occur after the man has been given the “all clear.” Late recanalization are extremely rare and occur in approximately 1 out of 4000 vasectomies.

For more information this topic, read our article on post-vasectomy recanalization.

Surgical error

Although uncommon, it is possible for a vasectomy to fail due to a surgical error. This is why it’s important to find a skilled doctor who has a good track record and has performed numerous operations. General physicians will often offer vasectomy services, but it’s usually best to go with a urologist due to their higher levels of experience and specialization.

The risk of surgical error (however small it may be) is another reason why the post-vasectomy semen analysis is so crucial.

Chances of becoming pregnant after vasectomy

The vast majority of post-vasectomy pregnancies occur in the first few months after the operation when the man may still have active sperm in his ejaculate and the couple doesn’t use an alternate form of birth control. As mentioned previously, these are known as “technical failures” and are not the result of an unsuccessful operation.

Even taking into account these early failures due to “user error” the failure rate of vasectomy is still favorable to many forms of birth control. One CDC study looked at 1,000 couples and found that of the 11 failures, half occurred in the first three months and no failures occurred after 18 months. The Association of Reproductive Health Officials gives an overall first-year failure rate of .10%, or 1/1000.

If the couples use birth control until the man is cleared by semen analysis, the risk of getting pregnant after vasectomy goes down to 1/2000 (.05%).

These figures will vary depending on the source and the parameters of the study, but the general consensus is that when a man follows his doctor’s post-operative instructions carefully and waits for the all clear before having unprotected sex, the chances of conceiving after vasectomy are very low.

It’s important to note that many studies on vasectomy failure were performed before the advent of new surgical techniques such as thermal cautery and fascial interposition. These new methods have further increased the effectiveness of vasectomy and have brought the recanalization rate even closer to 0%.

Comments

  1. Hi,

    To the man who has had a vasectomy 12 years ago and his wife is pregnant. Paternity testing will only break your heart if the child isn’t yours! I live in a similiar position but I don’t want to know if the child is mine or not because the birth was so beautiful and the baby girl opened her eyes wrapped up in a nappy and these lovely blue eyes looked up at me!
    My Dr said there is a beautiful little baby (and she was) needs my help and I will always be her Daddy and this has proved the cause regardless of getting a paternity test! (My Ex now) said she didn’t know but had had an affair so I don’t want to know because my daughter lives with me know and is 14 years old.
    Go with what your heart tells you, miracles can and do happen for a reason,

    Hope this helps,

    Regards Mitch

  2. Hi,

    On July 9th of 2008 my husband had a vasectomy. In early September semen analysis was done and came back clear with no sperm. Last week (October 21) I found out that I’m pregnant! The pregnancy was dated to only 3 weeks old so conception occurred after sterility was confirmed. I haven’t had sex with anyone else besides my husband. You’d think that getting pregnant with “no sperm” be impossible but somehow it happened to us. An additional semen analysis was done a couple days ago and still came back azospermazoic (no sperm present). Not sure how “semen analysis” are performed but they don’t seem to be very accurate.

  3. Not sure if you’re even still checking this but seens how the last response was oct. 08′ decided to reply, prolly won’t be as comforting considering it’s coming from the wife and not the husband of our situation but my husband and I have been together for 1.5 yrs now and sept. 08′ I hadn’t had my monthly but decided it was stress because there was no way I was preggo since my hubby had a vasectomy done 12 years ago after his 2nd child w/ his ex wife, but as a couple weeks went by I went out and bought a preggo test to put my hubby at ease of stressing. Annnd well lets just say as of today Jan 27, 2009 I’m currently one day from being 20 weeks preggo and honestly still in shock that this happend. I haven’t cheated or been unfaithful to my man, think if you’re going to cheat you might as well end the relationship because obviously it’s not working. But we haven’t had a sperm check done to see if he’s still supposably sterile so who knows maybe the vasectomy reversed itself, either way I look at this as a miracle because as you said in your post what are the chances of this happening. Anyways hope your situation ended on a good note.

  4. Well I am a mom to be for the 3rd time. I was dating a man for almost a year and a half -off and on,he told me he had a vasectomy and so there is no way I can get pregnant. Not true.
    I dismissed my late period,and other symptoms due to stress. I was not with anyone else at the time,and when I took a test-convinced in my head that is would say no-I was STUNNED! I started to cry because I knew that he would never believe me.
    I told him the news ,and that was our last conversation.
    I asked him to get tested,he refused saying I was crazy…ect.
    This breaks my heart,because I was SO careful,and though I did not plan on another child at this time in my life-I will raise it alone.

    Please-no matter how it turns out-keep in mind the feelings of that child.
    Sometimes that right thing to do is the hardest. You will know in your gut-what that is for you.

    Wishing you all the best.

  5. my husband has had a vasectomy almost 14 to 15 years ago. i went to the doctors because i slight bleeding, my doctor did an ultrasound and found out today 6/4/2010 that I have a sac in my uterus getting pregnancy test done to confirm tomorrow. wish me luck.

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