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Endometriosis is the name given to tissue like the lining of the uterus (the endometrium) when it grows where it should not, in locations other than in the cavity of the uterus itself. It can affect the lining of the pelvis and abdomen (the peritoneal cavity), including the surfaces of the pelvic and abdominal organs. This web page considers Web Page 16 will consider its treatment. To the gynecologist or surgeon looking inside your abdomen (at a laparotomy or a laparoscopy carried out for one reason or another), endometriosis typically has a dark brown appearance, in the form of spots or cysts. This color comes about because it bleeds each month at about the same time that the lining of the uterus menstruate. Because the blood has nowhere to go it gets stuck in the tissues, dries out and goes dark. If the endometriosis has formed a cyst in an ovary (it happens to about one in eight women with endometriosis), the semi-fluid material in the cyst is rather like chocolate in its color and texture, which gives rise to its usual description as a "chocolate cyst". The tissue most affected by endometriosis is the serosa of the peritoneum, which is the one-cell-thick, smooth membrane that lines all of the pelvic and abdominal cavity and its organs (see Web Page 13), together with the soft supporting tissue just under the serosa. The peritoneum anywhere can be affected, even under the diaphragm, but in general the closer the peritoneum is to the ovaries the more likely it is to be affected by endometriosis. Behind the uterus, the surface of the bladder, and the ovaries themselves are all common locations. In 1986 my friend and colleague Professor Peter Russell, a pathologist in Sydney, helped me to study a range of abnormal appearances in the peritoneal cavity to work out what they were. We took biopsies of more than 160 such lesions. The great majority turned out to be endometriosis. We published our results in the American Journal of Obstetrics and Gynecology, and from this time on gynecologists have recognized what we called "nonpigmented endometriosis" ... early endometriosis that has not developed yet to the point of bleeding and so does not have the usual brown color. Nonpigmented endometriosis can have the appearance of thickened, white tissue; gland-like excrescences that look a bit like the endometrium itself; and red, flame-like lesions that are full of blood vessels. Researchers at the Gasthuisberg University Hospital, in Leuven, Belgium, have since shown that these nonpigmented lesions can be just as chemically active as, or more active than, more typical pigmented endometriosis, secreting substances capable of disturbing reproductive function. How common is endometriosis?Return to Top In the past about one in a hundred women had very troubling symptoms of endometriosis, including severe pain and abnormal bleeding bad enough to lead to an operation. But endometriosis is a lot more common than this. Often it causes minimal or no symptoms. Many women have it without ever knowing about it. If it's not causing symptoms there’s no need to worry about it (unless it’s discovered by accident, say, in someone very young, who might be likely to develop symptoms as she gets older). Among women in their thirties whom I’ve operated on to rejoin tubes to reverse a sterilization operation, about 20 percent have had some endometriosis, whether they have symptoms or not. In women I investigate with a laparoscopy because they’re having trouble getting pregnant, the incidence is about 40 percent. This makes endometriosis very common -- too common, strictly speaking, to justify alling endometriosis "abnormal"! Nonetheless it's a major cause of symptoms and suffering in women. What symptoms does it cause?Return to Top The symptoms that suggest endometriosis include pain, in the form of painful periods (dysmenorrhea) and painful sexual intercourse (dyspareunia), and abnormal bleeding, particularly premenstrual spotting and, later, heavy periods (menorrhagia). Dysmenorrhea should be suspected as being caused by endometriosis if it gets worse instead of better as a woman grows out of her teens; if it starts to last longer than the first day of menstruation; or if it is increasingly felt in her back. The pain of dysmenorrhea can be caused by the endometriosis bleeding as the endometrium does at menstruation, but with congestion and trapping of blood in the endometriosis tissue. More often, the same hormones -- the endometrial prostaglandins -- that cause normal, first-day menstrual cramps are released by the endometriosis at menstruation time, making the cramps coming from the uterus worse and more persistent than they would otherwise be. Note, though, that menstrual cramps, especially in teenagers, can be severe without endometriosis being present; non-endometriosis dysmenorrhea, even though distressing, usually becomes less severe once a woman is in her late teens or early twenties, especially after a pregnancy and childbirth. A common site for endometriosis is on or below the ligaments that support the uterus from behind, at the level of the cervix, and which lie just below the ovaries. These ligaments are the uterosacral ligaments, running from the sacrum (the lowest part of the back-bone) to the uterus, and endometriosis affecting them is one reason why dysmenorrhea is often felt in the back. Because these ligaments are located behind and to the sides of the uppermost part of the vagina, pain with sex (dyspareunia), is another symptom of endometriosis; it's characteristically felt deep inside the vagina, sometimes particularly after a period, when the endometriosis will have become congested. The dyspareunia might be felt from the time of first intercourse or it can develop in sexually active women who previously had no symptoms with sex. If scarring occurs in the uterosacral ligaments from the repeated irritation and bleeding each month, the uterus can be pulled backwards -- a producing a retroverted uterus -- which can make dyspareunia worse. Not all pain felt in the pelvis, whether or not it’s associated with your periods, is caused by endometriosis (click for what else can cause it). And many women with endometriosis will have no significant pain. Need they (or you) worry? In general, no. Having endometriosis is not like, say, having a positive PAP smear. Rarely does it lead to complications if it's not causing pain. Abnormal bleeding Return to Top Premenstrual spotting or premenstrual staining is the most characteristic symptom of endometriosis. (I won't abbreviate this to PMS, because it has nothing to do with the premenstrual tension syndrome; let's call it PMSP instead.) Periods start in a quite definite manner for most women. It’s usually abnormal to have spotting or staining -- whether fresh or dark in character -- that lasts more than about twelve to 24 hours before menstruation begins properly. The association between PMSP and endometriosis was discovered 20 years ago by Dr Anne Wentz and her colleagues in Memphis, Tennessee -- but it still not well known among gynecologists. We have since found that even a small amount of spotting or staining, sometimes separated from the actual period by several days, correlates with the presence of endometriosis in more than 80 percent of patients -- a surer correlation than for either dysmenorrhea or dyspareunia, both of which can have other causes. This strong association was true both for infertile women and for women who had been referred for reversal of a previous sterilization operation. PMSP is therefore an important clinical symptom; but PMSP is especially interesting scientifically because it may be a clue to explaining the fourth symptom of endometriosis -- infertility -- which we'll get to shortly. In the absence of a desire for fertility, rarely is PMSP a troublesome enough symptom to need investigation and treatment. Bleeding between periods can, however, can be substantial enough to be troublesome. It’s not always clear, though, whether such bleeding is due to endometriosis or to a hormone imbalance associated with abnormal ovulation, particularly in the case of teenagers and older women. How do I know if I've got endometriosis?Return to Top There are three common ways endometriosis prompts you to see your doctor. Teenagers usually go, or get taken, because they have very painful periods, sometimes with bleeding between them or with spotting before the periods. After visits to several doctors, each reluctant to take symptoms seriously, laparoscopy will eventually be decided on, and the endometriosis revealed. The most common way that endometriosis is discovered in women in their 20s or 30s is during tests if they’re having trouble getting pregnant. Just how important the endometriosis actually is in causing the infertility varies a lot. In general, the more substantial the endometriosis is, and the more other symptoms there are such as increasing pain or premenstrual spotting, the more likely it is to be an important factor behind not conceiving. Older women -- those in their later 30s or 40s -- are most likely to have endometriosis discovered if they’re developing heavy and painful periods, troublesome enough for them to see their doctor. Among the tests that will usually be done are a transvaginal ultrasound (+ click for picture), which might show some other causes for the symptoms (such as fibroids, an endometrial polyp and, sometimes, adenomyosis -- see Chapter 17), but which will not reveal endometriosis unless there’s a chocolate cyst from endometriosis visible in the ovary. If you’re having an ultrasound done for these symptoms, make sure you have it during or just after a period, so that the ultrasound appearance of a normal corpus luteum is not mistaken for an endometrioma (or vice versa). Just at the end of a period is the best time to have this test. So the diagnosis of endometriosis can sometimes be suspected if there’s an abnormal cyst seen on transvaginal ultrasound. But it can also be strongly suspected if a careful vaginal examination reveals nodules, often tender, below or to the side of the cervix. (I should say though that detecting the signs of endometriosis in young girls is more difficult, because vaginal examination, except gently, under anesthesia, is usually not an option.) Confirmation then comes by looking for it and seeing it at laparoscopy. And that same laparoscopy can often be used to treat it (see Web Page 16). What causes endometriosis?Return to Top Many diseases and disabilities are the result of both hereditary and environmental causes acting together. Endometriosis is no exception. Inheriting endometriosisReturn to Top Professor Joe Leigh Simpson, now of the Baylor College of Medicine in Houston, Texas, but in 1980 at North Western University in Chicago, studied the families of 123 women with proven endometriosis. Nine of their 153 sisters (aged over 18) and 10 of 123 of their mothers had also had diagnoses of endometriosis made. This means that of the first-degree relations there was particularly substantial endometriosis in 19 of 276 - a prevalence of 17 percent. Furthermore, only one of 104 sisters of the patients' husbands -- i.e. sisters-in-law -- and only one of 107 husbands' mothers -- i.e. mothers-in-law (non-genetic relations used as a control group) -- had had endometriosis of similar severity. So, if you have a positive history of endometriosis among your closest relations, you’re about seven times more likely to have endometriosis. This substantial increase in relative risk of endometriosis if you have a mother or sister with it is consistent with endometriosis being inherited by the interplay of several genes. Environmental influences: ovulations and menstruationsReturn to Top We know that different women are at different inherited risk of developing endometriosis. But there's also a special risk factor for endometriosis apart from this hereditary tendency ... and this is the number of ovulations and menstruations a woman has had. Two things happen in the ovarian or menstrual cycle that are crucial in the development of endometriosis. First, the ovaries, with each ovulation, pour huge amounts of hormones, especially estrogens, out of the follicle into the peritoneal cavity. If there's tissue there that's potentially even a little bit sensitive to estrogens, it will respond and grow. With each ovulation there is another chance of this. Second, all women who menstruate and who have fallopian tubes that aren’t blocked will bleed backwards during their menstrual period, out through the fallopian tubes and into the abdomen. Menstrual blood, coming as it does from an endometrium that’s come apart and is all set to regrow itself over the next few days, is presumably chock full of growth factors and other substances that the endometrium uses to rebuild itself. It could even contain some viable endometrial gland cells. So with each ovulation and each menstruation there's another opportunity for abnormal growth. Modern women, who have many, many more ovarian and menstrual cycles than their predecessors through history and prehistory (see the box, Endometriosis and the modern woman), are now sharing the effects in the form of endometriosis. Thus we have two reasons so far as to why some women get endometriosis early, some get it late, and some never get it at all. We have the likelihood that women can have a varying genetic susceptibility to it. And we have this "environmental" variable, the number of ovulatory menstrual cycles a woman has had. It's the accumulating effects of ovulatory menstrual cycles that’s the explanation for how the prevalence of endometriosis increases with age and increases in women who delay having children. It's also clear from the genetic influences why some women develop endometriosis at a young age, whereas other women never develop it at all. It can cluster among close relatives for genetic reasons, yet many affected people have no relatives affected by it (sisters or daughters are still more likely not to develop it than they are to develop it). Once it's present, continuing ovulation and/or menstruation usually makes it develop further. Environmental pollution too?Return to Top There are indications that endometriosis might be getting more and more common for reasons beyond the social circumstances that have increased the experience of ovulation and menstruation. Part of the increase, to be sure, is that many women are postponing having children. Doubtless too, we're more likely to diagnose it than we were in the past. More laparoscopies are done than they used to be for investigating the once-more-tolerated synptoms of pain and infertility. We're also aware, now, of nonpigmented endometriosis (click for Figure), which a decade ago was often missed. But still there’s the possibility that there might be other environmental factors that have changed over the last generation or two, just as there seem to be more environmental contributions to oligospermia in men (discussed on WebPage 10). Recent discoveries in monkeys have pointed the finger at an industrial pollutant, the poison dioxin. While we all await more definite information before we can be sure, the box, Dioxin gives the details of the studies so far. How does endometriosis develop? Does it spread ?Return to Topp One theory on the way endometriosis gets going --the so-called implantation theory, first developed by Albany, New York, gynecologist John A. Sampson in the 1920s -- has it that live cells from the endometrium in the uterus are shed into the menstrual flow. With passage of menstrual flow back out through the tubes, surviving cells are said to attach themselves to the serosa near the ends of the tubes to produce endometriosis. Further shedding from these "implants" then results in further implants, and so the endometriosis gets more extensive. Just how often this might happen is still debated. The other main theory on how endometriosis gets started and develops is the metaplasia theory, by which the body for some reason determines that there are patches of sensitive tissue in the abdomen, or peritoneal cavity. These patches, it’s thought, then respond either to the repeated huge amounts of estrogen with every ovulation or they respond to repeated exposure to menstrual blood with every menstruation and the growth factors it presumably contains. Metaplasia then involves the peritoneal tissues undergoing a metamorphosis from simple serosa (with nondescript little blebs) to having the structure of endometrial like glands (clearly endometriosis), followed by dark pigmentation once bleeding has occurred. Any apparent spread of endometriosis, according to this theory, is just the slower development of some patches in comparison with others. Traditionally, it’s been the implantation theory that’s captured the imagination, especially in North America -- to the point that each “lesion” of endometriosis has rather presumptively come to be called an "implant". Since we’ve recognized the early, nonpigmented lesions of endometriosis I mentioned at the beginning of the chapter, some gynecologists are becoming convinced that endometriosis only very uncommonly seems to spread from one location to another, previously completely normal location. Unlike cancer, which spreads and spreads, most cases of endometriosis, once the lesions have matured, remain more or less restricted to the same locations throughout a woman's menstrual years. This is not to say that cysts of endometriosis in the ovary don’t often grow back after being removed, but if you've gone 20 years without having endometriosis cysts in the ovary, for example, it's unlikely that they will suddenly then start developing. Endometriosis and infertility: chicken or egg ?Return to Top How ironic! You’re more likely to have endometriosis if you delay having your first baby (because of all those ovulatory menstrual cycles over the years), yet once endometriosis is there it contributes further to not getting pregnant. There are also special conundrums that need explaining. Every experienced gynecologist knows of some paradoxes that just don’t seem to make easy sense. On the one hand, treating the mildest forms of endometriosis rarely seems to be followed quickly by pregnancy. On the other hand, we’ve all seen examples of substantial endometriosis in which pregnancy has happened without any apparent problem. It's like saying that curing a mild form of a disease is more difficult than curing a severe case! How do we explain these paradoxes? The key to understanding endometriosis and infertility is to realize that it’s not like having blocked tubes, or not ovulating, or having no sperm. Unless the scarring that sometimes goes with it obstructs the tubes (accounting for no more than five percent of women with endometriosis) (click for an example), there's always a chance of getting pregnant: it’s a cause of subfertility, not sterility (discussed on Web Page 1). Instead, experience (and theory) is consistent with endometriosis gradually decreasing fertility as it becomes more extensive -- or as it becomes more active in whatever the ways are that it actually gets in the way of conception (see the box, Mild or moderate ...). In practice, though, the chance of getting pregnant naturally, as with most of the reasons for decreased fertility, depends more on the length of time you’ve been trying, and on your age, than it does on the "dose" of the particular infertility factor that's been discovered. Paradoxically, the more severe endometriosis is, the more likely it is that endometriosis is the chief explanation of a couple’s infertility and that successful treatment will be followed by pregnancy. The arithmetic of this paradox is explained on Special Web Page 1. Briefly, because we don’t understand or can’t point the finger at all the reasons why normal fertility varies between different couples, the more dramatic the cause for infertility that’s found, the more likely it is that it will be the only cause, and that treating that particular recognized cause will lead to conception. Treating endometriosis is the subject of Web Page 16.
Copyright © Robert Jansen, W.H.Freeman and Scientific American Books (New York) and Allen & Unwin (Sydney) |