To understand the disease known as Endometriosis, it is important to understand that the normal version of this type of tissue is the innermost lining of the uterus (womb) that sloughs away with each period. It's all part of the normal cycling in what is a monthly preparation for implantation of a fertilized egg. When conception doesn't occur, the cycle begins anew by casting off the old layer so as to build up a new one. This innermost lining is called "endometrium," from which the actual disease of endometriosis gets its name.
The disease of endometriosis is when endometrium or endometrium-like tissue is in other places besides the uterus. Since it is a very hormonally reactive tissue, and since it isn't discarded away on a tampon to the outside world, it can sit in a woman's pelvis and thicken and shrivel cyclically with no way out. It is a fairly bloody substance, and since blood is very inflammatory to the lining of the abdomen, it causes pain and scarring that can cause adhesions (things meant to be floating free sticking together). Besides the bloody inflammation, there are other chemical irritants that not only contribute to the inflammation, but also can retard the normal conception process.
Infertility is one of the big tip-offs of endometriosis. Although pain is a famous component, some cases of endometriosis have no pain at all. There are two main routes of infertility at the hands of endometriosis. One, as mentioned above, is the inflammatory and humoral disruption of a conception-friendly environment. The other is adhesion formation that may kink a fallopian tube or put up a mechanical barrier between the ovulating ovary and the tube which would normally carry the egg toward conception at mid-tube.
Endometriosis is a terrible disease for many reasons. The pain and suffering, and the depriving a couple of children is one thing. The other thing is that it is a surgical diagnosis. In other words, a doctor cannot examine a patient and say, "You have endometriosis." He or she can say a patient may have it, but the actual determination has to be based on seeing it in the abdomen or pelvis. Since this can only be done by laparoscopy or other surgery, the judgement of a woman's doctor is very important:
If a doctor is too aggressive in ruling out or ruling in endometriosis, then too many needles laparoscopies will be done. If the doctor is too conservative, not enough laparoscopy will be done and too many undiagnosed cases of endometriosis will be allowed to continue on damaging a woman's reproductive chances. It's a difficult fine line to negotiate, and most doctors over the years narrow that line to a point that is comfortable for them.
My own fine line involves time limits. If a woman wants me to investigate her pelvic pain, I do a careful exam, including a thorough history. An ultrasound is also part of my work-up to rule out other diseases or cysts. If all of my findings are normal, including negative cultures for sexually transmitted diseases, and if the only abnormality remaining is the history of pain, I usually give her discomfort a time limit. We together determine at which point it will be appropriate to get more invasive with the diagnostics--meaning a laparoscope exam. (The laparoscope is the insertion of a lighted tube into the belly button to actually look into the pelvis.)
During the course of the laparoscopy, if endometriosis is identified, it can be burned away and the tubes checked for patency. Post-operative therapy for endometriosis involves a wide assortment of medical treatments. The newest one is called a GnRH-agonist, a drug that stimulates the production of female hormones until her ability to make them "burns out," which then starves any remaining endometriosis.
GnRH-agonists are fairly effective, but the down side is that they put the patient into a temporary menopausal state. After a few months of the treatment, assuming the patient hasn't discontinued therapy herself because of the menopausal side effects, the drug must be withdrawn anyway because of the dangers of osteoporosis. What all of this means is that the disease is terrible, the diagnosis method is very inconvenient, and the treatment is terrible, too. But we strive to do better. Newer drugs are on the pipeline already in hopes of treating the disease without the side effects.
Endometriosis tends to run in families. What causes it is still mysterious, but the most commonly held theory is that it's from "retrograde" menstruation--that is, menstrual tissue is squeezed backwards through the tubes during a period, and it drips onto the pelvic surfaces. But this theory doesn't explain how some women can have endometriosis in their lungs, brain, or elsewhere. There are reports of nosebleeds with periods!
Although our treatment of this very frustrating disease still goes unperfected, we nevertheless are pursuing it aggressively in the research areas of pharmaceuticals, surgical techniques, and early detection. The most important thing a woman can do is report pelvic pain to her gynecologist. Her very fertility may depend on it.