It's the wound that any man who has ever put on a uniform and deployed to a war zone has thought about.
In "The Sun Also Rises," Ernest Hemingway's hero Jake Barnes deals with it stoically and never really talks about it. It's that kind of wound.
The Defense Department's Trauma Registry reported that between 2001 and 2013 while serving in Iraq and Afghanistan, 1,378 male service members incurred injuries to the genitals and other parts of the genitourinary tract.
Of 965 cases examined, 65 had severe injury to the penis or amputation, Dr. Jean Orman of the U.S. Army Institute of Surgical Research and the Joint Trauma System reported in December 2014 at the Bob Woodruff Foundation.
These wounded find it tough to talk about. So do their loved ones.
At a symposium on genitourinary wounds held in 2012 at Walter Reed National Military Medical Center in Washington, D.C., Rep. Tim Murphy, a Republican from Pennsylvania, noted, "On a national scope, Congress is so filled with the psyche of embarrassment that they cannot talk about the topic of genital trauma."
But medicine and science may soon restore what war took away.
At Johns Hopkins University School of Medicine in Baltimore, a medical team is preparing to conduct the first penis transplant in the U.S. At Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina, researchers are working on a bioengineering a replacement penis grown from a patient's own cells.
Johns Hopkins has been cleared to perform 60 penis transplants as part of a clinical trial, with the first slated to take place anytime in the next few to a few months, depending on availability from a deceased donor, according to the school. Its focus will be on those whose injuries were caused by trauma, in particular combat veterans, Dr. Richard Redett, director of pediatric plastic and reconstructive surgery, explained in a question-and-answer page on the school's website.
Doctors have been able to construct penises using skin grafts for decades, but the procedure does not provide full functionality.
A penis transplant, if successful, will provide that full functionality, including the ability to have children naturally if the patient's testes are intact and able to produce sperm.
To date, there have only been two penis transplants in the world, one in China and another in South Africa. The China recipient later asked to have the penis removed because of "psychological rejection," according to a report in The New York Times.
The South African surgery proved more successful, to the point where the recipient became a father, the Times reported.
Redett, in the Johns Hopkins interview, said the family of a deceased person must specifically authorize the donation of a penis.
"Many people might think that organ donation means unquestioned consent for donation of all organs. That's not the case with the face, hand or penis," he said. Also factored in to determining an appropriate donor is blood type, age -- within five to 10 years -- and skin tone, he said.
As with other transplants, the recipient can expect to be on medications to help ensure their body does not reject the donor penis.
In North Carolina, a team led by Dr. Anthony Atala is working on growing a replacement penis in the lab using the cells of the recipient. If successful, the bioengineered penis would eliminate the risk of rejection because the new organ would have been grown from the recipient's own tissue.
The Wake Forest team is now doing the required studies required by the Food and Drug Administration for clearance to begin human testing. Atala said those clinical trials are probably two years away.
But if the trials are successful, a soldier or veteran whose penis is amputated or destroyed by blast injury would not need to rely on a donor or deal with the risk of organ rejection.
Several years ago Atala's team at Wake Forest Institute for Regenerative Medicine successfully grew new penises for rabbits that went on to have normal sexual function, including procreate.
"You basically take a small piece of tissue from a patient - less than half the size of a postage stamp," Atala said. "You then expand the cells outside the body ... You're then able to reconstitute the cells into actual structures using 3-D scaffolds and put it right back into the patient."
Atala was the first to successfully grow an organ in the laboratory -- a bladder -- and such bladders have now been engineered and placed in dozens of patients over the past 16 years.
"There is a complexity in terms of the organs," he said. "Flat structures are the least complex - such as skin. The second level of complexity are tubular organs, like blood vessels, because they're tubular, not flat and they have two major cell types instead of one."
The third level would be the "hollow, not-tubular organs," such as the bladder and stomach. These are "more architecturally complex, the cells are more complex and there is more interaction with other organs.
"And finally the most complex organs are the solid organs, like the kidney, the liver -- the penile organ would be in this category, as well," he said.
"We have not yet implanted a [bioengineered] solid organ," he said.
The bioengineered penis would begin by taking a tissue sample about half the size of a postage stamp from the intended recipient and growing it in the lab. As the cells multiplied, they would be inserted into a "scaffold" in the shape of the penis and created biocompatible, fully degradable materials such as those used for dissolving sutures.
Once the replacement penis is grown, it would be attached to the patient.
"Once in the body the scaffold goes away and, as it goes, the cells lay down their own scaffold," Atala said. "The cells sense they need that architecture underneath them and secrete their own architecture. They build their own bridge."
The cells also grow back nerves.
"Both the vessels and enervation comes from the body," he said. "Let's say you have surgery and they make an incision over a nerve. It cuts the nerve. At first you feel numb, then it starts itching, and then you get your sensation back. That's basically because it cuts through the nerve and the nerve has regrown.
"It's the same thing. You put the tissue in and the body does the rest. It puts the nerves back in," he said.
Though the Defense Department has over the years has funded research into penile transplantation and organ regeneration, such procedures will remain outside Defense Department and VA medical facilities until clinical trials are over and the surgeries become standard medical practice, officials said.
Those who have a penis transplant or, later, a bioengineered penis replacement during the clinical trials will, once they've cleared the protocols established for the trials, receive all follow-up care, including medicines, counseling and therapy, from the VA, said Dr. William Gunnar, the VA's National Director of Surgery.
"If an active duty soldier or veteran [has this kind of surgery] under a research protocol, will VA provide follow-on care? The answer is 'yes," said Dr. William Gunnar, the VA's National Director of Surgery. "These wounded warriors we hold in the highest regard."
--Bryant Jordan can be reached at email@example.com. Follow him on Twitter at @bryantjordan.