Pregnancy after the snip: Exceedingly rare, but not ‘mission impossible’

Dear Dr G,

In conjunction with the theme of contraception this month, I am hoping to put Dr G on the spot for my conundrum in life.

I am a happily married man in my late thirties and have two beautiful kids.

Both my wife and I agree we have completed our family.

One thing we cannot agree on is who should shoulder the responsibility for sterilisation.

My wife referred to your article and highlighted the drawbacks for women to undergo surgical tying of the tubes as this must be carried out under general anesthesia with higher risks.

I also accept the risks for the snip in men is lower and generally straightforward.

But I read somewhere that the failure rate of vasectomy is also high, as many report pregnancies despite the snip.

My argument is that total contraception is “mission impossible” for men, therefore it is better to have women tie the tubes to ensure it is flawless.

We are putting Dr G on the spot for the real data for vasectomy failures.

First, can you explain the vasectomy procedure and why it can fail?

What is the most common interval for such failures?

Can vasectomy failure be detected?

What is the longest interval of failure after the snip?

Surely that has shaken and stirred a stable relationship.

Hope to hear from you soon.

Yours truly,

Mission Impossible Mike

Vasectomy is a surgical intervention performed for the intention of permanent contraception. During this procedure, the vas deferens on both testicles are segmentally cut and tied to prevent the flow of sperm mixing with the seminal fluid.

As most of the ejaculated semen is derived from the secretion in the prostate, the snip will result in “normal” ejaculation, without the alteration of the climatic sensation, amount, colour, odours, or texture of the semen, despite having no active sperm within the ejaculates.

As such a mode of sterilisation is easily performed and has virtually no long-term impact on sexual pleasure in men, the acceptance of such contraception is gaining popularity amongst men who choose not to have more children.

In North America and European countries, vasectomy acceptance is at around 10%. Even in conservative Asian countries like South Korea, the vasectomy rates is reported to be as high as 21% as a form of permanent contraception.

Worldwide, New Zealand has the highest levels of vasectomy, with 18% of all sexually active men, and this constitutes 25% of all married men there, having undergone the snip!

With so many men putting their trust in vasectomy as a mode to enjoy the pleasure of unprotected sex with no pregnancy consequences, it is reasonable to ask the question on the efficacy of vasectomy to completely occlude the passage of the stubborn little fellas!

Despite the near perfect efficacy, vasectomy is still not 100% “play and no pay” foolproof. Yes, that’s right, a guy can have the snip and still get his partner pregnant!

And it is not the “milkman” that is responsible! Vasectomy failure can be classified as early and late failure.

Early failure is by far the commonest, when the pregnancies occur due to unprotected sex too soon after the snip. “Hanger-on” sperm usually can survive in the vas deferens for months after the surgery.

Most clinicians would insist on a post-procedural semen analysis to verify a successful outcome. Many men may have failed to do so due to inconvenience, forgetfulness or embarrassment.

Of course, some men may be such an “eager beaver” and start having unprotected intercourse and end up with failures.

In fact, the United States FDA has even cleared a home test kit called SpermCheck Vasectomy that allows men to perform the test themselves; sadly, the compliance for the post-vasectomy semen analysis still remains low.

Late failure of vasectomy is rare, but well documented in the medical literature. This is generally related to postoperative infections, abscess and a short segment of vas that was removed. The Royal College of Obstetricians and Gynecologists states that vasectomy failure rates in the late stages is about one in 2000 vasectomies.

This is based in one review in 2005 revealing total failure rates of 183 from 43,642 vasectomies (0.4%).

Another publication reported sixty pregnancies happened after a review of 92,184 vasectomies, which translates to a total failure rate of 0.07%.

When pregnancies occur years after the snip, sensational reporting from the press is inevitable. In fact, the most recent media report of late failure of vasectomy was seven years after the snip.

Before striking fear down the spine of millions of men who have had the vasectomy and worry about its failure rates, let me reiterate the fact that vasectomy failure is exceedingly rare!

In the darkest hours of World War II, Winston Churchill famously said: “Success is not final, failure is not fatal: It is the courage to continue that counts!”

When Dr. G is often put on the spot to verify whether the unlikely event of pregnancy is possible after the snip, his advice for those fearing the darkest hours of vasectomy failure is: “Success of vasectomy is almost final, Near impossible failure may seem fatal: Post-op sperm counts are the best courage to tackle the Mission Impossible after the snip!”