A man in India had to have his penis partially amputated after he developed gangrene due to an erection that lasted two days.
The anonymous 52-year-old introduced himself to doctors because he could not get rid of the "painful and sustained" erection.
Grumpy doctors quickly drained blood from his penis, but left a catheter and tightly clothed his penis, causing the patient to develop black gangrene.
They were left with little option but to amputate after it reported back to them showing signs of severe tissue damage caused by an acute loss of blood circulation.
Details of the highly unusual case at King George Medical University in Lucknow, North India, were published last month in the British Medical Journal.
The man suffered from priapism, a medical term for a persistent and painful erection.
It is not known what caused the patient's condition, but experts consider an erection lasting more than 48 hours from a medical emergency.
The NHS says that priapism can be caused by sickle cell disease or by using illegal or legal prescription drugs for erectile dysfunction, including Viagra.
"We removed the urethral catheter," Saqib Mehdi wrote in the case report.
"But still the black color of the glans deepened the next day and a clear line of demarcation became visible between it and the shaft of the penis."
Three weeks after the life-changing operation, the man was able to urinate as usual and now has a "healthy wound."
Dr. Mehdi suggested that the catheter and tight dressing after the procedure could have caused gangrene in the patient.