Some of the latest virtual reality simulators that teach doctors how to perform complex surgery have been demonstrated at the British Association's Festival of Science.

Believe it or not, a plastic model of a human bottom is part of one of the most sophisticated tools now in use.

It is a sigmoidoscope simulator, designed to mimic the tricky technique in which a flexible probe connected to a camera is inserted into a patient's colon to look for signs of disease.

The procedure requires a great deal of skill, which is why surgeons at St Mary's Hospital in London have been working with the simulator to see how effective it is at training surgeons for the real thing.

The probe on the simulator is connected to a computer that generates images on screen, just like those inside a real patient.

Simulated cancers

Nick Taffinder described to the festival how the simulator could be used to train doctors to search out bowel cancers.

"The computer can generate any images you care to program into it," he said. "So you can place simulated cancers at various bits in the bowel - and remove them."

Also on display were computer simulators that mimicked keyhole surgery, in which long probes are used to do delicate operations through a small hole in the body, avoiding the need for a large incision.

Nick Taffinder said this type of simulation would never replace practise with real patients but it did allow trainee surgeons to learn some of the challenges of the technique before they had to do the operation for real.