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.