Affairs may do more than break hearts — they may break penises as well, a new study says.

Sex outside marriage, and sex that occurs under out-of-the-norm circumstances, may increase the risk of penile fractures, said study researcher said Dr. Andrew Kramer, a urologist at the University of Maryland Medical Center.

The heightened risk appears to be due to the unconventional situations, and consequently, locations, surrounding sexual acts, the researchers said. Men in the study who had suffered penis fractures commonly were having sex in unusual settings, including in restrooms or at work, when the injury occurred. The majority were having extramarital affairs.

In such atypical situations, sex may be rushed and involve unusual or awkward sexual positions, Kramer said.

"All these factors could make the man less able to protect his penis from an unexpected sudden downward thrust leading to the fracture," Kramer said.

'Broken' penis

A penile facture, or "broken penis," is an injury that occurs to the erect penis. There are no bones in the penis; the "fracture" refers to tearing or laceration of a fibrous membrane called the tunica albuginea, which surrounds the spongy tissue in the center of the penis.

A "fracture" is followed by hemorrhaging, swelling and loss of erection. While previous research has focused on the physiological mechanism of the facture, and how to surgically treat it, no study has looked at exactly what men were doing when they broke their penises. Kramer's study aimed to fill this gap.

Kramer studied 16 cases of penile fractures treated at the University of Maryland Hospital between 2004 and 2011.

Half of the patients were having extramarital affairs, the study found. Most were having sex in unusual places, including bathrooms, cars and elevators. Only three patients were having sex with their own wives in their own bedrooms, Kramer said.

Sex can be risky

While penile factures are rare occurrences, they may be underreported due to the potentially embarrassing circumstances surrounding the injury, Kramer said.

Kramer cautions that, just as with sports, sex can come with risk of injury.

"If you're having acrobatic sex…you do have to be careful," Kramer said. "If you are doing something in a weird position or a weird situation…you do have to be careful of fracturing the penis."

The study is published online on Sept. 22 in the Journal of Sexual Medicine.

Pass it on: Men who have sex under unusual social circumstances may be at increased risk for penile fractures.

This story was provided by MyHealthNewsDaily, a sister site to LiveScience. Follow MyHealthNewsDaily staff writer Rachael Rettner on Twitter @RachaelRettner. Find us on Facebook.