A man had to have part of his penis amputated after being treated for a two-day erection.

The 52-year-old man turned up at a medical facility in Delhi, India, with an unusually-sustained erection. The erection had lasted for more than 48 hours, and required treatment to alleviate the pressure.

Doctors created a T-shunt (using a scalpel through the head of the penis to create an "escape hole" for the trapped blood) for the swelling to subside. He was fitted with a catheter, and dressing was applied. Though this sounds alarming, the most likely side effects from the procedure are swelling and bruising of the penis, as well as a semi-rigid erection that can last for several days.

Unfortunately for the man described in the BMJ Case Reports, the next day the head of his penis became discolored, and started to turn black.

Four days after the onset of his erection, the man was transferred to the Department of Urology, King George's Medical University, where he was examined and treated.

First, doctors removed the catheter and performed a suprapubic cystostomy (surgically inserting a catheter in the abdomen in order to drain the bladder) in order to reduce risk of infection associated with a urethral catheter. The authors noted they were not sure why this had not been performed before.

The gangrene, where a loss of blood supply causes tissue to die, continued to spread on his penis.

"Still the black color of the glans penis deepened over the next day," Dr Saqib Mehdi wrote in the case report. "And a clear line of demarcation became visible between it and the penile shaft." A photo can be viewed in the paper in the BMJ Case Reports, though we'd heavily advise against it.

The medical team decided that in order to stop the gangrene spreading, they would have to perform a glansectomy (amputation of the head of the penis).

It's unknown what caused the priapism, the name for a prolonged and often painful erection, though doctors suggest the treatment of the patient for it may have been a factor in causing the gangrene that led to his amputation.

"Various factors like urethral catheter, tight pressure bandage dressing around the penis and local infection alone or in combination have been implicated in causing penile gangrene in cases of priapism," the authors write.

"In our case too, the patient was catheterized and a compressive dressing was applied around his penis."

After the operation was performed, he recovered quickly and was discharged within 48 hours. Three weeks later he was seen again, and his wound was found to be healing well.