Not all pelvic pain or back pain in women is due to endometriosis. Pain that’s felt at period time, or soon afterwards, is the most typical of endometriosis pain. The pain can be spasmodic, but really only at period time. It can be accompanied by diarrhea and pain evacuating the bowel, but again really only around period time, except perhaps in particularly severe cases of endometriosis affecting the tissue that lies between the vagina and the rectum (in which case the endometriosis can be easily felt by the doctor on vaginal examination). More than a few hours of pain at ovulation can come from endometriosis affecting the ovary.

Spasms of pain -- rising, knife-like, to a crescendo, then sooner or later abating -- have to come from a muscular tissue that is contracting in an involuntary way inside the abdomen. The organs a woman has that have such involuntary muscle tissue in them are the uterus, the fallopian tubes and the intestines. Spasms at times other than around period time and ovulation are almost always coming from the intestines, the bowel.

Because endometriosis is so common, very many women whose pain is really from abnormal contractions of the bowel and/or heightened sensations of pain from the bowel (together known generally as the irritable bowel syndrome), have the label "endometriosis" placed on their condition and go through an extraordinarily frustrating time with their doctor trying to get relief from their symptoms through treatments that will work only for endometriosis.

Premenstrual tension (PMT) is another condition whose symptoms are commonly confused with those of endometriosis. PMT symptoms usually precede the period (though some women feel emotionally at their worst toward the end of menstruation).

Many women with endometriosis have both PMT and the symptoms of endometriosis. Unless you and your doctor distinguish them carefully, treating one without the other will inevitably result in much dissatisfaction. (To be sure, this is one major reason hysterectomy has a bad name, because whatever hysterectomy does for symptoms of endometriosis it does nothing for the monthly symptoms of PMT.)