A man in South Africa who underwent a penis transplant has impregnated his girlfriend, according to news reports.

But it's not clear whether the man's transplanted penis works the same way an undamaged penis would, said Dr. Andrew Kramer, a urologist at the University of Maryland Medical Center who wasn't involved in the transplant.

The penis is not necessary for a man to ejaculate or urinate, so it's possible that the man's transplanted penis doesn't function completely normally, Kramer said. Ejaculation is controlled by the spinal cord and does not require the penis; the rhythmic contraction of pelvic muscles forces semen outward, as if from the bulb of a syringe, he said.

It's possible the man could ejaculate without the penis getting erect, he added. "Maybe ejaculate just dripped out," and he got the woman pregnant, Kramer told Live Science. [8 Wild Facts About the Penis]

Freak accident

The 21-year-old man, whose name has not been released, had all but 0.4 inches (1 centimeter) of his penis amputated after a ceremonial circumcision went horribly wrong, according to the BBC.

Penile amputations are incredibly rare complications of circumcision, but there are some recorded cases of it. In one case, a 7-year-old boy had part of his penis amputated in an accident involving a guillotine-like circumcision tool, according to a 2011 article in the Korean Journal of Urology.

And, in extremely rare cases, dirty conditions can cause serious bacterial infections that require penile amputation, according to a 2013 study in the journal Archives of Plastic Surgery.

Complicated procedure

The South African man received his transplant on Dec. 11, 2014, in a 9-hour procedure performed by doctors at the Stellenbosch University in Cape Town and Tygerberg Hospital in South Africa. The surgeons used techniques pioneered in face transplantation, according to news reports. He resumed sexual activity five weeks after the operation, and his girlfriend is now four months pregnant, the BBC reported. (No DNA tests have been done to confirm paternity.)

A penis transplant is a tricky operation, Kramer said. He and his colleagues have discussed the possibility of performing them, for instance, on veterans who have been injured in explosions in Iraq or Afghanistan. However, the doctors decided against the idea because too many things can go wrong, Kramer said.

"Historically, they haven't ever worked — that's been the issue. There's so many moving parts to the whole thing," Kramer said.

For instance, the blood vessels, nerve endings and urethra all must be aligned and connected properly, and the outer portion of the penis must be aligned at its base to the rest of the organ.

"The penis is anatomically complicated: Half is in the body, half is outside; it doesn't just stick to the skin," Kramer said.

And, unlike with other organs — for example, a transplanted kidney — the ultimate appearance of a transplanted penis is important for the operation to be considered a success, Kramer said.

Nowadays, for men with injuries, doctors typically take muscle tissue from the forearm and reconstruct a penis, Kramer said. A man typically maintains sensation in whatever portion of his penis is left.

As good as new?

Though the South African man's transplanted penis may be functional in the sense that it is a conduit for ejaculate and urine, that's no guarantee it looks, feels or even operates like an undamaged penis, Kramer said.

In addition, there's no way to know whether the transplanted penis looks like an undamaged penis because no pictures have been made available, Kramer said.

The South African man is the second person to have received a penis transplant, and the first to have impregnated a woman. A previous penis transplant recipient in China asked to have his removed after a severely negative psychological response, CNN reported.

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