The kidney is removed in a bag
US surgeons say they have successfully removed a healthy donor kidney through a small incision in the back of the donor's vagina.
Removing the kidney through "a natural orifice" speeds up recovery and gives a better cosmetic result - avoiding a six inch abdominal scar - they say.
The Johns Hopkins team say the 48-year-old woman who donated the organ to her niece on 29 January is "doing well".
Surgeons have also removed gallbladders and appendixes through the mouth.
Diseased gallbladders, kidneys and appendixes have been removed through the vagina before.
But this is believed to be the first time that doctors have managed to harvest a healthy donor kidney for transplantation in this way.
Dr Robert Montgomery, chief of the transplant division at Johns Hopkins University School of Medicine, Maryland, who led the team that performed the operation, said: "Surgeons have been troubled by the need to make a relatively large incision in the patient's abdomen after completing the nephrectomy to extract the donor kidney.
"That incision is thought to significantly add to the patient's pain, hospitalisation and convalescence. Removing the kidney through a natural opening should hasten the patient's recovery and provide a better cosmetic result."
The operation left three pea-size scars on the Lexington Park woman's abdomen, one hidden in her navel, from where the wand-like camera and operating tools were inserted through small incisions.
Once the kidney was cut from its attachments to the abdominal wall and its arteries and veins were stapled shut, the surgeons placed the kidney in a plastic bag inserted through an incision in the vaginal wall and pulled it out through the vaginal opening with a string attached to the bag.
Dr Montgomery said the surgery took about three and a half hours, roughly the same as a traditional keyhole or laparoscopic procedure.
With keyhole surgery, an incision is typically made below the bikini line to remove the kidney.
The surgeons hope the new procedure will lead more women to become donors.
Anecdotal reports suggest living donor transplant numbers went up after keyhole procedures became available.
Dr Anthony Kalloo, the director of the Division of Gastroenterology at Johns Hopkins University School of Medicine, who pioneered the procedure, said: "Natural orifice translumenal endoscopic surgery is the final frontier to explore in making surgery scar-less, less painful and for obese patients, much safer."
In the UK, living donor kidney transplants are increasing - from 589 in 2005-2006 to 829 in 2007-2008 - and now represent more than one in three of all kidney transplants.
But the number of people on waiting lists for a transplant is also increasing - nearly 7,000 people were on the list last year and more than half of these will still be waiting for a donor, according to UK Transplant.
A spokesman for UK Transplant said: "Any development that is likely to boost donor numbers would be positive for people on waiting lists.
"Although 90% of people in the UK say that they are in favour of organ donation in principle, only 26% of the population have actually registered on the NHS Organ Donor Register. We need more people to join the register."
David Mayer, consultant transplant surgeon at the Queen Elizabeth Hospital in Birmingham, said: "This is quite interesting in terms of having scar-less surgery and because one of the obvious problems after surgery is pain.
"There might be some discomfort but nothing like having a wound the size of a kidney on the surface of the body which might cause pain for several weeks."