Having 'the snip' without the chop

Vasectomy blocks the tubes carrying sperm to the penis

A new vasectomy technique which avoids the use of invasive surgery could encourage more squeamish men to have one, suggests a study.

Scientists in the US have used ultrasound to block the vas deferens - the tubes that carry sperm out from the testicles.

British experts say it could help shift the burden of sterilisation from women to men.

In most vasectomy operations across the world, a surgeon cuts out a 1.5cm section from the vas deferens.

Anything that's going to encourage men to come and have this done is a move in the right direction

Dr Marianne Perry, Marie Stopes International

The cut ends of the tubes are then either cauterised to seal them shut or blocked with silicone plugs.

Under the new system, the tubes are blocked without making any incisions, according to an article in New Scientist magazine.

The vas deferens are located and a plastic clamp is used to hold them in place in a pinched fold of the skin.

Built into the clip is a device that produces five watts of ultrasound.

A pulse of ultrasound is fired for between 20 and 50 seconds, heating the vas deferens to over 50C.

This kills cells in the tube wall, which coagulate and obstruct the tube.

Developing countries

Dr Nathaniel Fried, who pioneered the technique at Johns Hopkins Medical School in Baltimore, said: "You are essentially cooking the tissue."

Dr Fried's clip contains a water-filled latex balloon that sits between the transducer and the skin.

You are essentially cooking the tissue

Dr Nathaniel Fried

Pumping cold water through the balloon before, during and after the operation ensures the vas deferens can be heated without burning the skin.

So far the treatment has only been tried out on dogs, but Fried says it is so simple it could be routinely used without calling on the skills of a surgeon.

He said: "This could be especially useful in developing countries where people don't have ready access to trained surgeons and sterile hospitals."

Vasectomy is cheaper than female sterilisation and has a higher success rate, with fewer complications.

Dr Marianne Parry at Marie Stopes International thinks the new technique has strong potential.

She said: "Anything that's going to encourage men to come and have this done is a move in the right direction.

"So few men go for vasectomy. Women yet again have to take responsibility for sterilisation, which has a higher risk of failure than sterilisation for men."

Before the new technique can be used on men, Dr Fried will have to prove it can produce a permanent, effective blockage every time without causing burns to the skin.

Dr Fried said: "With a vasectomy, anything less than 100% success is not good enough."