Dear Dr G,

I am a 58 year-old man who recently discovered that my wife is eight weeks pregnant. The trouble is, I already had my vasectomy!

My wife and I decided that I should undergo sterilisation after our last child was born seven years ago. Of course, being a selfless and conscientious man, I decided to go through the vasectomy. The vasectomy itself was uneventful and I must say it has been liberating in our sex life, as the fear of parenthood is no longer in our minds during intimacy.

Needless to say, I was shocked when my 28-year-old wife informed me that she is now eight weeks pregnant, despite the vasectomy. I immediately went to see my doctor and had a semen analysis. I was told I have no sperm (azoospermia).

Putting Dr G on the spot, I will like to ask – isn’t vasectomy a guarantee of sterilisation? Can you tell me what are the odds of a vasectomy failure. If so, what is the mechanism of failure? Can my wife still get pregnant despite the azoospermia? I am confused!

Please help,

Vasectomy is the surgical intervention for sterilisation or permanent contraception for men.

During the procedure, the vas deferens (ductal systems that delivers the sperm to the ejaculate) will be identified and ligated. Such occlusion can prevent the sperm from entering the prostatic ducts, hence it is unable to reach the female eggs for fertilisation. Vasectomies are commonly done under local anesthesia in clinics. Such modality of contraception is significantly risk-free, less invasive and more cost effective, in comparison with female tubal ligations.

As a result, the decision to use vasectomy as a form of contraception has gain tremendous popularity in recent years, with some countries reaching 20% of all forms of contraception. With near 100% efficacy for sterilisation, even the remote possibility of vasectomy failure can send chills down the spine of men who built up the courage to go for the snip.

According to the Royal College of Obstetricians and Gynecologists, the spontaneous re-canalisation of the vas deferens following vasectomy is around 1 in 2,000. The 2005 review including both early and late failures revealed a total of 183 reconnections of the ligated vasa, from the astounding 43,642 vasectomies carried out. This translates to 0.4% of vasectomies destined for failure. Additionally, 60 pregnancies were recorded after 92,184 vasectomies.

Meaning the chances of the partner getting pregnant is about 0.07% after the snip. Although such statistics may seem alarming for men, the odds are much better than female tubal ligation having one in 300 failure rate.

The mechanism of errors in vasectomies can be divided into early and late failures. In early failures, this may be due to surgical errors during which the wrong tubes are removed. (Yes, this has happened even in the hands of the most skilled urologist).

Other causes of early failures may be due to lingering live sperm present in the men’s semen after the snip. Most doctors will encourage men to produce semen for analysis after three months, or 25 ejaculations, to verify their sperm-free status.

The late vasectomy failure although is documented, is exceedingly rare. It is estimated one in 4,000 men may face the “escape of the sperm” months or years after the ligations. This is believed to be due to scarring formed at the cut end of the vas deferens. The tiny channels can induce sperm granuloma resulting in nature delivering the gametes in a mysterious way.

The American photographer, Diane Arbus, noted for the images of marginalised individuals once profoundly said: “Love involves a peculiar unfathomable combination of understanding and misunderstanding.”

Meanwhile, Dr G’s response is: “Nature also involves a peculiar and mysterious combination or understanding and misunderstanding!” If the only way to identify the source of the sperm is through a DNA analysis of the offspring, will one be magnanimous enough to accept the “misunderstanding”?

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