Humans still make better surgeons than robots, carrying out operations in a shorter time yet making no more mistakes, a study has suggested.
Robotic-assisted surgery has grown substantially since the first machines were installed a decade ago, and is commonly used for prostate, bladder and kidney removal as well as for cutting out tumours.
It was hoped that robots would be more accurate, dexterous and quicker than humans, but a study has shown that they do not improve outcomes for patients, and operations take longer.
Researchers at Stanford University School of Medicine in the US reviewed nearly 25,000 operations in 416 American hospitals between 2006 and 2012.
They found that just 28 per cent of kidney removal patients who had keyhole surgery performed by a human surgeon were under the knife for more than four hours, compared with 46 per cent of those operated on by a robot. Robotic surgery was also around £2,000 more expensive per patient.
Dr Benjamin Chung, associate professor of urology at Stanford, said: "Although there was no statistical difference in outcome or length of hospital stay, robotic-assisted surgeries cost more and had a higher probability of prolonged operative time."
There are around 60 "da Vinci" machines in British hospitals offering assistive robotic surgery. Costing about £1 million each, the robots offer enhanced 3D vision and instruments such as tiny cameras and ultra-small tools.
The researchers say that robots are undoubtedly helpful in tricky operations, which require a high degree of delicate manoeuvring, or extensive internal stitching. But for less technically challenging surgery, such as the removal of a whole kidney, the new study shows that humans alone are likely to be better.
Although the authors say the operating time may decrease and that the cost differences between the two procedures will narrow over time, for now, the results show that robot-assisted surgery is not always the right choice.
Chung questioned: "Although robotic surgery has some advantages, are those advantages relevant enough in this type of case to justify an increase in cost?"
The research was published in the Journal of The American Medical Association.