A robotic surgical device takes measurements from a doctor and does the rest on its own, carving out bad tissue using precise jets of water.
The technology, dreamed up by Silicon Valley pioneers, has been tested for the first time at Tauranga Hospital - and is being touted as the future of medical operations.
Two prostate operations were successfully carried out on Wednesday by a team including California-based Procept Biorobotics founder Nikolai Aljuri and Auckland University associate professor Peter Gilling, a urologist at the hospital.
A surgeon, after examinations, told the machine how much tissue to remove, and inserted the robotic arm into the patients' prostates.
The prostates were suffering from benign prostatic hyperplasia, an enlargement of the gland that makes lives miserable for as many as a quarter of men older than 60.
The machine took over from there.
A jet of water as thin as a strand of hair and accelerated almost to the speed of sound tore off the affected tissue with precise, automated incisions, a process dubbed "aquablation".
Water jets avoid the usual complications of heat-based surgeries - instead of damaging neighbouring tissue, they affect only the problematic areas, which are softer with less collagen.
Once a clean channel was opened in the prostate, restoring a normal flow of urine through the neighbouring urethra, the device switched to its "aquabeam" mode - for cauterising the bleeding areas.
The jet was softened - so soft you wouldn't feel it if it was aimed at your eye - and used as a pipe to carry laser light.
The laser bounced off the insides of the water stream to reach the bleeding tissue, closing it up.
"It's novel," Dr Gilling said. "I'm the chairman of the international committee for surgical treatment of BPH, and we've just completed a review of all the different literature ... so I can confidently say what these guys are bringing to the table is completely unique."
"You set this thing up, and it does the work."
It made sense to automate routine procedures while surgeons focused on the more complex, he said.
The two Tauranga patients were quickly discharged after an overnight stay.
Dr Aljuri said the successful operations had been the moment he had been waiting for through four years of research.
"This is the future," Dr Aljuri said.
The biggest challenge had been to convince people that water jets could be so effective, he said. "It's still the beginning. The road is still in front of us. But at this time it looks positive."
Procept Biorobotics had come to New Zealand for its testing so it could work with Dr Gilling, a leader in the field, Dr Aljuri said.
Dr Gilling said a lot of pioneering medical research was being done in New Zealand. "And we speak English - which is huge for American companies.
"The interest is in coming to a country they know they can trust."
How it works
*A doctor takes measurements of how much tissue to remove and inputs it in a handheld computer.
*A robotic arm is inserted into the patient.
*Jets of water carry out the rest of the operation automatically.