Keyhole or minimally invasive surgery has been hailed as one of the great medical innovations of the century. Using the latest microtechnology, surgeons can perform major operations, without the trauma of conventional open surgery.

As a result, the patient should be able to leave the hospital quickly often, even an overnight stay is unnecessary and should enjoy a far less painful and speedier recovery.

Although initial research indicates these benefits have still to be fully proven, the technique is the fastest growing in the whole health field. It's already being used in one in five of all abdominal operations, and is likely to be used in 70 per cent of all operations by the end of the century. That would mean that, in the UK alone, it would be used in 2.1 million operations a year, according to current levels.

Quite an elevation for a technique that was introduced as recently as 1990 and whose benefits and dangers have never been scientifically tested.

Keyhole surgery involves making four or five minor incisions usually only five to seven centimetres long through one of which a device called a laparoscope is threaded. The laparoscope is the "eyes" of the surgeon, and a minute lens on its tip transmits pictures of the internal organs onto a video screen.

Other tubular instruments are threaded down the other incisions and the operation takes place via the video screen. If any growth or part of an organ has to be removed, it is first cut away and then compressed and squeezed through the incisions. The technique also involves the use of xenon light beams and lasers.

The laparoscope has been used for over 20 years by gynecologists, but only recently has the technology developed sufficiently to allow instruments to be fitted and used for investigative procedures (say, to check the state of a woman's ovaries), or to cut and perform ligatures (tying up arteries or cutting out tumours).

The entire process usually takes far longer than conventional, open surgery sometimes seven times as long. But surgeons report that patients usually have a far shorter hospital stay afterwards, and can be fully recovered even months sooner than they would be after a conventional operation.

While most experience has been on gall bladder surgery, and increasingly on abdominal procedures, it is a technique that is being used for other diseases. The first operation on cell cancer using laparoscopic equipment was carried out in 1991; the first kidney was removed using the procedure a year earlier.

Surgeons maintain that the escalation of keyhole surgery is patient driven.

While it would be only natural for patients to prefer keyhole surgery to the trauma of a major, invasive procedure, their consent can hardly be informed. There simply hasn't been enough research into the procedure and its after effects for anyone to claim to possess all the facts.

The shortage of beds in many hospitals coupled with the desire of surgeons to try the new technology and not to feel left behind would indicate that pressure is not coming from patients alone.

At a London inquest into the death of a woman who died after receiving a keyhole bowel exploration, it was claimed she had been frightened and confused when the technique was suggested. The surgeon denied this.