Surgeons at Johns Hopkins Medicine are planning to conduct experimental penis transplants in the hope of restoring urinary and sexual function to 60 wounded servicemen.

Doctors at the Baltimore institution have been practicing on cadavers to prepare for their first patient, said a medical school spokeswoman.

If the first round of transplants is successful, the procedure might be made available to men who have had cancer, and in gender reassignment surgery.

Johns Hopkins has been approved to conduct transplants only on injured servicemen, said spokeswoman Taylor Graham. More than 1,300 U.S. servicemen have suffered urogenital injuries since 9/11. Injuries that would have killed soldiers in the past are increasingly survivable, thanks to medical advances. But, especially for younger men, identity can be deeply tied to sexuality.

"When they wake up after getting hurt, they don't care if they're missing an arm or a leg. The first thing they do is to make sure, 'Is my penis still intact?'," Graham said. "They worry about the arms and legs later."

The procedures will involve only the penis and will not include the testes, Graham said.

Though operations have not been scheduled, they are expected to begin shortly at Johns Hopkins. Other hospitals elsewhere in the country also have been approved to perform the transplants, according to the United Network for Organ Sharing.

The technical and ethical issues involved in transplanting a penis are similar to those that come with face or hand transplants, said L. Scott Levin, a surgeon at the University of Pennsylvania, who led the world's first pediatric double hand transplant last year at Children's Hospital of Philadelphia.

All require several teams of specialists to stitch together blood vessels, nerves, and small muscles during procedures that last many hours, Levin said. And none is considered lifesaving.

"If you don't have a functioning heart, we know you're going to die," Levin said. "We know you can live without hands, a face, or a penis, but your quality of life is extremely compromised. Some would say, 'Without them, 'I'm not living.' "

Chinese doctors made the first attempt to transplant a penis in 2006 to a man who had lost his own in an accident. But because the recipient and his wife "could not psychologically accept" the donation, the penis was removed after 14 days, according to the Journal of the American Medical Association, which was first to report the ambitious Johns Hopkins plan.

In 2014, surgeons in South Africa successfully grafted a donated penis to a 21-year-old who lost his own in a botched ritual circumcision.

A professor of bioethics at New York University raised the issue of antirejection drugs, which are needed after a transplant but can prove toxic over time. "We don't worry about it when it comes to the heart, because without the transplant they're dead," said Arthur Caplan. "But if you transplant someone at 20 with a new penis, and their kidneys fail at 30, is that a success?"

He also noted that the prospect of one's face or penis going to someone else might make it harder to get people to sign up for organ donation.

"It does have some potential to frighten away people from making lifesaving donations," Caplan said. "I don't think people will be that eager to donate these kinds of externally visible organs."

But volunteer organ donors who have checked off the requisite box on their driver's license applications or renewal forms should not be worried, said Anne Paschke, spokeswoman for the United Network for Organ Sharing.

"Rest assured. When you sign up to become an organ, eye, and tissue donor, it does not include the face, hands, uterus, or penis," Paschke said. "There has to be a separate request and consent for those."