Endometriosis, frequently referred to as just “endo”, is a genetic disease that affects women and causes pain, inflammation, and infertility. The severity of pain varies from person to person, just as the severity of disease does, however they are not linked. What this means is that one person may have mild disease and severe pain, whereas someone else could have severe disease and minimal symptoms. This has led physicians and researchers to call endometriosis “enigmatic”, meaning perplexing or mysterious. In reality it’s really no more mysterious than considering that Tiger Woods played a whole round of golf on a broken leg, while my mother can fall down and get no more than a bruise and stay in bed for 3 days. Pain is perceived differently by different individuals. For details on this, please see My Philosophy on Treating Pelvic Pain Patients.
So back to endo- the formal definition is “endometrial glands and stroma existing outside the endometrial cavity”. Essentially, it is tissue that resembles the endometrium (lining of the uterus), that exists other places. Most often, it is found in the pelvic peritoneum, or the lining of our abdominal cavity. The most frequent locations are the uterosacral ligaments, culdesac, pelvic sidewalls (under the ovaries), and over the bladder. It also is commonly found on the intestines (large and small bowel, appendix), in the wall of the bladder, and in the muscle of the uterus where it is called adenomyosis. It can also be found less often on the diaphragm, lung, and has been reported in the brain and male prostate.
Contrary to popular opinion, it does not spread from one location to another, and can remain rather static. When it does grow, it typically stays in the same location and grows only deeper. There may be 2 separate varieties of endo- that which stays superficial within the peritoneum, and that which infiltrates the deeper tissues of the pelvis such as the rectovaginal septum, bowel wall, bladder wall, and ovaries. This is referred to as Deeply Infiltrating Endometriosis (DIE). Unfortunately, because we can’t install a permanent time-lapse camera in the pelvis, or even do repeated laparoscopies every year for 10-20 years, we don’t have a great understanding of how the disease progresses. We do have snapshots of the disease in different women at various ages that allows us to know some things. Redwine wrote a paper looking at this very subject, and what he found was that older women don’t have more locations of endometriosis, but they do tend towards having deeper disease with more bowel involvement in women in their 30s than in their 20s. This tells us that endo doesn’t metastasize like cancer, but grows fairly slowly in place, and where it is initially is where it will be in the future.
What causes endo? Again, popular opinion and the medical facts diverge, mysteriously. Most people, including gynecologists, believe that endo is caused by retrograde menstruation (Sampson’s Theory), a process by which endometrial cells from the uterine cavity flow backwards through the fallopian tubes and wind up in the pelvis. Prominent doctors and researchers have done intellectual contortions trying to make their observations conform to this theory, trying to use the “clockwise peritoneal fluid circulation” to explain why lesions are more common in some areas, such as why there’s more endo found on the left uterosacral ligament and sidewall than on the right. Based on this theory, there should be more endo on the gallbladder than the diaphragm, but endo has only been reported 3 or 4 times on the gallbladder, and while diaphragmatic disease is rare, it’s numbers are probably in the many hundreds to thousands of cases. Based on this theory, there should be endo anywhere on the bowel including the mesentery, yet lesions are almost always found directly across from the mesentery (the antimesenteric surface). Based on this theory, women in their 40s should have endo everywhere, yet they have no greater number of lesions than younger patients. There are many other inconsistencies- endometriosis should be genetically identical to endometrium, yet it is not. An abrupt transition between normal and abnormal tissue should be able to be seen microscopically – yet research shows a gradual transition between normal tissue and endometriosis, not what would be expected by an autotransplant mechanism. Sampson’s theory can’t explain lesions in the lung and brain, or in males. Nor can it explain the findings by Dr. Signorili of endometriosis in 9% of baby girl fetuses he autopsied. Finally, 85% of women have retrograde menstruation. Why don’t all of them have endo?
So if it’s not Sampson’s theory, what is is?
The theory of origin that fits best with the facts at hand is that of metaplasia. Metaplasia is a word that describes benign changes of tissue from one type to another. This happens frequently in normal processes such as within the cervix, and is different than neoplasia, which is where normal tissue turns into cancer. Metaplasia of the peritoneum has been extensively documented by pathologists as the cause of primary peritoneal carcinoma, which is essentially ovarian cancer in women who have had their ovaries removed. The peritoneum can also morph into cervical, tubal, and uterine muscle type tissue as well as endometrial type. This explains the existance of endometriosis outside the pelvis, in fetuses and pre-pubertal girls, as well as the static nature of the disease and that there are locations within the pelvis where we frequently find lesions, and places where it is virtually never seen.
Metaplasia also means we can cure endometriosis – yes I said it! While I’m sure you’ve been told endo can never be cured, it always comes back and the only way to deal with it is to either go on Lupron or have all your reproductive organs removed, I will bet you a million bucks that whoever told you that believes in Sampson’s theory. The metaplasia theory not only integrates with everything we know to be true about endo, but it means that since the disease doesn’t spread, if we remove it and make sure to get it all, it won’t come back…. No, this is not heresy, it is science.