A young US military veteran has received the world’s most extensive penis transplant in a 14-hour operation in Baltimore.

The veteran, whose genitals were blown off by a bomb, got a new penis, scrotum and portion of the abdominal wall from a deceased organ donor.

The surgery was performed last month at Johns Hopkins Hospital by a team of nine plastic surgeons and two urological surgeons. It is the world’s most complex and extensive penis transplant yet, and the first performed on a combat veteran maimed by a blast.

The operation was estimated to have cost $US300,000-$US400,000 ($393,000-$524,000), although the team of nine plastic surgeons and two urological surgeons worked for free.

Two other successful penis transplants have been performed – in South Africa in 2014 and at the Massachusetts General Hospital in 2016. But they involved only the penis, not the scrotum or surrounding flesh.

BREAKING NEWS: @HopkinsMedicine performs the first total penis and scrotum #transplant in the world. https://t.co/HO7uwbOXta pic.twitter.com/BbWP931YFc

— Hopkins Med News (@HopkinsMedNews) April 23, 2018

In this latest operation, surgeons transplanted a single piece of tissue that measured 25 centimetres by 28 centimetres and weighed about two kilograms.

“We are hopeful that this transplant will help restore near-normal urinary and sexual functions for this young man,” said Dr Wei-Ping Andrew Lee, professor and director of plastic and reconstructive surgery at the Johns Hopkins University School of Medicine.

The recipient is a veteran who was injured in Afghanistan and wished to remain anonymous. Except for his immediate family and a few close friends, he had told no one about the nature of his wounds, he said.

“It’s a real mind-boggling injury to suffer, it is not an easy one to accept,” he said.

He has recovered from the surgery and is expected to be discharged from the hospital this week.

“That injury, I felt like it banished me from a relationship,” he told The New York Times last week. “Like, that’s it, you’re done, you’re by yourself for the rest of your life. I struggled with even viewing myself as a man for a long time.”

Four weeks after the surgery, the veteran said he felt whole again.

“When I first woke up, I felt finally more normal … [with] a level of confidence as well. Confidence … like finally I’m OK now.”

Image: Devon Stuart for Johns Hopkins Medicine

Dr Lee said the goal of such a transplant was “to restore a person’s sense of identity and manhood”.

For most men, that means regaining the ability to urinate while standing up, and to have sex. Dr Lee thinks the operation can make both possible. Urination is expected first, within a few months.

Although the scrotum was transplanted, the donor’s testes had been removed for ethical reasons: Keeping them might enable the recipient to father children that belonged genetically to the organ donor, something not considered acceptable by medical guidelines.

Medical teams in the US are evaluating more candidates for the surgery. But it can take a long time to find a matching donor – the Johns Hopkins patient waited more than a year on the transplant list.