What causes cramping pain?
Possibly a combination of uterine contractions, ischemia.
Using novel MRI methods our study shows that menstrual cramping pain occurs immediately and 30-70s after a decrease in myometrial T2 signal intensity. The combination of early and delayed subjective pain report – relative to a decrease in T2 weighted signal intensity – provides new evidence supportive of a contribution of myometrial activity and impaired hemodynamics to menstrual pain.
A video of results is on twitter: