Many injuries caused by a specific form of S&M are not being reported to doctors - due to embarrassment.
The practice of kinbaku, which originates from Japan, sees people tying each other up with rope very tightly in an elaborate pattern.
Wounds occur when the ropes aren't tied correctly and can result in limb necrosis and other serious ailments.
There's also a risk of whiplash, neck injuries, burns, jaw problems, dislocated joints and nerve issues.
According to The Daily Beast, there has been an increase in the number of unreported injuries caused by BDSM.