A 20 year old woman gives a history of pain in the lower abdomen for 2-3 days every month staing approximately 3 days before the menses. The most probable etiology is?

Menstrual pain is known as dysmenorrhea & if it stas 2 - 3 days before the onset of menstruation that is known as congestive dysmenorrhea. Endometriosis most characteristically presents with congestive dysmenorrhea. Fibroid classically presents with spasmodic dysmenorrhea (congestive dysmenorrhea can also seen) which is present mostly on the first & second day of the menstruation. Mittelschmerz (ovulation pain) - ovulation pain occurs in mid cycle.