'The snip' has been a convenient and popular form of contraception since the Sixties. But is the operation always effective? And are there any risks?
"Child-hating ER hunk" George Clooney is keen on it, according to the tabloids. Bishop Philip Boyce of Rathoe, Donegal, has branded it as "against God's law". One man, writing to The Sun's "Dear Deirdre" column, said it had sent his sex drive "through the roof"; another complained it had made his wife too randy. A woman at an auction in Devon, meanwhile, bought it for pounds 70 as a present for her husband.

Vasectomy, or male sterilisation, introduced in Britain in the Sixties, is fast becoming a popular contraceptive option, with about 90,000 men undergoing the operation annually (although according to one London clinic, it is usually the woman who suggests it). In the last few years, some men have been put off "the snip" by studies suggesting a link with cardiovascular disease and cancer. But a report on vasectomy published this month is, for the most part, reassuring.

The operation itself, widely available on the NHS, is simple and safe enough: carried out under local anaesthetic, it involves cutting the vas deferens, the tube that carries sperm from each testicle to the penis. A small cut is made in the skin of the scrotum and either a small piece of each tube is removed, or the tubes are cut and the ends closed. The operation takes about 10 minutes and usually results in some bruising and tenderness (tight underpants help).Slight bleeding may occur; in some cases, sperm leaks out of the tube and collects in surrounding tissue, causing inflammation. Most men, however, return to work within a few days and resume sex within a week to 10 days, although they need to use another method of contraception until sperm left in the tubes have been ejaculated. Only after semen has been analysed and found to be sperm-free is a man considered sterile.

Despite male fears that it makes a man less "manly", vasectomy does not normally affect the ability to ejaculate or come to orgasm; although it blocks the passage of sperm, it has no effect on the glands secreting fluids that form most of the semen. Since the testicles still produce male sex hormone, a man's sex drive and ability to have an erection should not be affected.

Vasectomy is a highly effective method of contraception, though in up to five cases in every 1,000 the severed parts of the tube reunite and sperm reappear, necessitating further surgery. But in the long term, is it safe?

Most of the scares associated with vasectomy have been shown to be without foundation. In the Eighties, animal studies linked vasectomy to cardiovascular problems, but to date there is no evidence of this in research using humans. A suggested link between vasectomy and testicular cancer has not been substantiated. Several studies have indicated that prostate cancer may be twice as common among vasectomised men, but other studies do not show this; most experts feel that the risk, if any, is small. In the 65-74 age group about 3 men per 1,000 in Britain develop the disease. If the risk were doubled for vasectomised men, this would mean 6 vasectomised men per 1,000 per year. In this age group, the chances of dying from another cause are five times greater.

The new review of research, published in the British Journal of General Practice, points out that the effects of vasectomy on the reproductive tract, particularly the testicles, are not well understood: a small group of men develop chronic discomfort and testicular pain, probably caused by scar tissue forming around the nerves. The psychological effects of vasectomy are less well documented. In a detailed study of 68 men who had had vasectomies, about 10 years previously, published in the British Journal of Family Planning, 12 per cent said it had impaired their orgasmic intensity, erectile function and sex drive (while that of their wives had increased); only 61 per cent felt that sexual function was completely undisturbed. The majority of such problems are thought to be psychological (and could well be the result of ageing rather than surgery), which is why it is crucial that anyone considering vasectomy should undergo counselling.

About 3 per cent of vasectomy patients later change their minds about having a family, usually because they have changed their partners. Reversing the operation, although complicated (and costly - it is available only privately, for about pounds 1,000), is more successful than in the past, thanks to new techniques using microsurgery. If a reversal is carried out within three years of the original operation, success rates - (ie, the woman getting pregnant) - can be as high as 76 per cent; after 15 years they fall to less than 30 per cent. Many men produce antibodies to their own sperm once they have had a vasectomy, and therefore suffer from low fertility following reversal, although some doctors are now using IVF to overcome this problemn

Cherrill Hicks