Pathophysiology
During each monthly bleed prostaglandins are released by the endometrial cells as they are shed. This process leads to uterine contractions, ischaemia and vasoconstriction and in women with severe dysmenorrhoea prostaglandin levels have been found to be particularly high, especially during the first 2 days of bleeding (Holder, 2011). In women with primary dysmenorrhoea pains are most intense during the first or second day of the menstrual flow, consistent with the time of maximal prostaglandin release (Dawood, 2006). The cramping pains experienced have been described as similar to those experienced when prostaglandins are given to induce labour or an abortion. Vasopressin is a hormone that is also though to play a part in inducing menstrual pain because of its ability to cause vasoconstriction of blood vessels. Elevated levels have been reported in women with primary dysmenorrhoea