A condition called endometriosis is the most common. This is a condition in which the lining of the uterus, called your “endometrium”, which sheds and bleeds every month, backflows through the tubes during your menses and reimplants itself into the lining of your abdomen, or onto your bowel, or bladder, ovaries, tubes, or the surface of your uterus. There it cycles, just as it does when it is located inside your uterus, and embeds itself into the organ on which it is now located. Needless to say, this is not comfortable. Typically endometriosis causes lower abdominal crampy pain that begins a few days prior to your periods, radiates into your back, can be excruciating, and is often relieved a few days into your period. It can also cause pain with intercourse and infertility. Sometimes it does not cause symptoms at all. More about endometriosis
Adenomyosis is a form of endometriosis in which the lining of the uterus invades into the muscle layer and cycles there. It can cause pain with intercourse and intense pain with periods.
A chronic low grade infection (“chronic endometritis”) can cause mild to severe pain with periods.
Hormonal changes that affect the bowel and the pelvic floor can cause pain that is worse with periods. Bladder conditions, such as interstitial cystitis, can be exacerbated during menses.
Sometimes, we never find out a specific cause for pain with menses, which doesn’t mean that it isn’t happening. The theory is that some people produce more prostaglandins with their menses or that their menstrual period may induce a painful pelvic spasm if they are prone to that.
Almost always, we can improve pain with menses. Usually we start with a history and physical and a pelvic ultrasound. Laparoscopy and tests of the pelvic floor may also occasionally be part of the work-up.