Endometriosis, sometimes called endo, is a chronic disease in which the kind of tissue that normally makes up the lining of the uterus (the endometrium) is found other places within the body. Endometriosis is one of the primary causes of infertility and of menstrual pain.

The wandering endometrial tissue can be attached to other organs or implanted within other tissues. Usually endometriosis is confined to the pelvic cavity, with clumps of unwanted endometrial tissue on the ovaries and around the outside of the uterus. Less frequently it is found in the vagina, near the small intestine, bladder, or appendix. But endometrial tissue has been found as far away as the lungs and the nasal passages. It has also been found in skin and in scar tissue remaining after surgery. These occurrences far from the pelvic area are rare.

No matter where it is located, whether in its rightful place inside the uterus or elsewhere, endometrial tissue responds to estrogen stimulation. Every month all the misplaced endometrial tissue acts just like the lining of your uterus: it swells and thickens, gets ready to receive a fertilized egg, and then, responding to hormonal changes, breaks down and sloughs off.

It is this monthly cycling that leads to the symptoms associated with this disease: men strual pain, pain during intercourse, and infertility. Endometriosis can cause inflammation, internal bleeding, and the formation of scar tissue or blood-filled cysts.

Figure: Common sites of en dometriosis in the pelvis

Figure: Common sites of en dometriosis in the pelvis

What causes endometriosis?

No one really knows the answer to this crucial question. There are several contending theories, but no single one accounts for all the places in the body that endometrial tissue may appear. It is suggested that endometriosis is a disease of the immune system, that it is a genetic disease, or that it is an inflammatory disease. Some researchers hypothesize that the endometrial tissue may migrate through the lymphatic system to other sites in the body. Others suggest that a hereditary tendency plus an immune reaction to one’s own tissues may bring on the disease. Still others believe that environmental factors, for example exposure to the pesticide dioxin, may contribute to endometriosis.

One of the oldest explanations is the menstrual backflow theory, according to which some of the flow from your menstrual period, including bits of endometrial tissue, backs up through the fallopian tubes and enters the pelvic cavity. The bits of tissue then implant themselves on nearby organs and begin to grow. However, this hypothesis cannot account for endometrial implants in sites far from the pelvis, such as the lungs or nose; nor can it account for the fact that the cervix and other locations regularly exposed to the menstrual flow rarely get endometrial implants.

I am inclined to favor the “potential tissue” theory, which is based on embryonic development. The tissue that lines many of the body cavities is called “totipotential” tissue because it can develop into anything — it has the potential to become any other kind of tissue. According to this theory, this totipotential tissue that covers the lining of the lungs, for example, lies dormant until a girl begins producing estrogen; then, in the presence of estrogen, it gradually changes into endometrial tissue. The answer may lie in a combination of these theories, and several disease-causing mechanisms may be at work to account for endometrial implants in the distant places they have been found.

Who is at risk for endometriosis?

Endometriosis appears to be more common now than when first described in 1920, perhaps because we have better tools for diagnosing it, but also because current social patterns favor later childbearing. The “typical” woman diagnosed with endometriosis is in her late 20s or early 30s and does not have children. Endometriosis used to be thought a disease primarily of white women, but as more black women have begun pursuing careers and putting off childbearing, the incidence has risen in them as well. For unknown reasons Japanese women are more at risk than Caucasians. In parts of the world where the culture emphasizes early childbearing, endometriosis is rare. Endometriosis is more common in women whose sisters or mothers have the disease, but it is certainly not a genetic disease like hemophilia, whose inheritance can be predicted with some statistical certainty.

Does endometriosis always get worse with time?

Because endometriosis is primarily a disease of women of childbearing age that responds to estrogen, it goes on as long as a woman produces estrogen. Generally the longer it goes on, the worse it gets; but this is not always the case. Some researchers estimate that only between 25 and 40 percent of women with mild endometriosis go on to have more severe stages of the disease.

Two natural occurrences interfere with the progress of endometriosis. Menopause, after which the ovaries no longer produce estrogen, usually brings relief, although some women do have endometriosis later in life. Pregnancy, during which the usual balance of hormones is altered, also can stop the advance of the disease.

Why does it get worse over time?

When the endometrium itself breaks down every month, it has somewhere to go: it flows out the vagina. But the blood and debris formed by misplaced endometrial tissue may have no natural exit. If the endometrial implants are inside the pelvic cavity (but outside the uterus), the tissue simply bleeds into whatever tissues surround it. This process, which goes on every month unless treated, can cause inflammation and pain, and eventually will produce scar tissue.

Early on, endometriosis may appear as little speckles or flecks of tissue, scattered here and there in the abdominal cavity. Over time, as scar tissue develops, the patches of endometrial tissue may cause one organ to adhere to another. These adhesions may, for example, glue the ovaries to the back wall of the pelvic cavity. Sometimes more advanced endometriosis forms a cyst, called an endometrioma or a “chocolate cyst,” filled with dark blood that looks like chocolate syrup. Chocolate cysts can be very large, as big as basketballs. They are fragile and, unlike other kinds of cysts or tumors, are difficult to remove surgically in one piece. These masses may change the position of the uterus or push against the fallopian tubes, distorting the normal pelvic architecture. If the tumors and scarring build up, they may “freeze” or “fix” the reproductive organs in place and interfere with their functioning.

In 1985 the American Society for Reproductive Medicine established a system for categorizing, or staging, endometriosis, so that physicians would have a standard way of describing its severity. Although the guidelines are somewhat controversial, the simplified version in Box 5 gives a general picture of the stages of the disease.

What are the symptoms of endometriosis?

Although up to 30 percent of women have no symptoms, the three classic symptoms of endometriosis are menstrual pain, pain on intercourse, and infertility. Your personal symptoms depend on where the wandering endometrial tissue has landed. If it is in your pelvic cavity near the uterus, you may feel abdominal tenderness or have painful menstrual periods with or without heavy, irregular flow. You may have pain between periods, just after your period ends or before it begins. You may have pain with intercourse. By contrast, if you have a large endometrial cyst on your ovary, you may have no symptoms at all. If endometrial tissue has lodged in your nasal passages, which happens rarely, you may have nosebleeds around the time of your period. If it has landed in your lungs (also very rare), you may have bleeding into your lungs, a condition known in medical terms as catamenial hemothorax, and cough up blood during your periods.

Stages of Endometriosis

Stage I: Mild
  • Small scattered implants on lining of pelvis or surface of ovary
  • No scarring
  • No adhesions
  • No endometriomas (endometrial cysts)
  • No involvement of bowel
Stage II: Moderate
  • One or both ovaries involved, small endometriomas (endometrial cysts)
  • Mild adhesions
  • Endometrial implants may show scarring
  • Ligaments supporting uterus may be involved
  • No involvement of bowel
Stage III: Severe
  • Large endometrial cysts
  • Involvement of both ovaries, ovaries fixed in place by adhesions
  • Fallopian tubes blocked or fixed in place
  • Uterus pushed out of its normal position or fixed in place
  • Bowel, bladder, or ureters involved

Strangely, there is no correlation between the severity of your symptoms and the severity of the endometriosis. Sometimes people with tiny endometrial implants have a great deal of pain. Or women with huge masses of endometriosis may have no symptoms.

Can endometriosis turn into cancer?

Endometriosis is not the same thing as endometrial cancer, which is a malignant disease of the actual lining of the uterus. Nor is endometriosis a disease that is likely to turn into cancer. Although it is possible for an endometrial implant located in the ovary to become malignant, it is very rare.

If you have endometriosis, are you more at risk for premenstrual syndrome or other menstrual problems?

There does seem to be some correlation between premenstrual syndrome and endometriosis. The link maybe physiological, since endometrial tissue is hormonally active and premenstrual syndrome seems to be hormone dependent. There may also be a psychological link. If you know that your period is going to start next week and you are going to feel awful or even be in acute pain, then it is reasonable that you may be depressed and anxious at the prospect. If your endometriosis is causing infertility, the anxieties surrounding that issue may stress and depress you.

How does endometriosis interfere with fertility?

Infertility is one of the hallmarks of endometriosis, but no one is sure exactly why or how endometriosis prevents conception. Sometimes the causes seem to be mechanical. Maybe the endometriosis blocks the fallopian tubes or causes adhesions that interfere with the process of fertilization; or perhaps endometriosis invades the ovaries so that they are unable to function properly.

Sometimes a woman having difficulty getting pregnant may appear to have no blockages caused by endometrial tumors. Her fallopian tubes are open. Her pelvis does not contain large endometrial implants. Yet she does not become pregnant.

It is possible that endometriosis causes something to go wrong with ovulation. Many researchers believe that endometrial implants are not chemically inert; rather, they are producing hormones or other substances that may interfere with ovulation. This theory also helps explain why women who have endometriosis experience increased pain with their periods: the endometrial implants may be producing extra prostaglandins, the hormonelike substances that cause menstrual cramping.

How is endometriosis diagnosed?

Your medical history is an important tool in diagnosing endometriosis, but the best way to confirm any suspicion is through laparoscopy, a minor surgical procedure, that is performed under anesthesia and involves only a small incision. If the endometrial implants are small, your doctor may use laparoscopic tools to remove the endometriosis at the time of the diagnosis.

If the endometrial implants are large enough to distort or enlarge your uterus or change the size of your ovaries, your physician may feel thickening around the ovaries or around the back of the uterus during a pelvic exam. While a pelvic exam can suggest that endometriosis is your problem, other conditions might cause the same physical signs; the only certain diagnosis is through laparoscopy. Ultrasound will pick up cysts or large implants, but if your endometriosis is in the form of scattered bits here and there, ultrasound probably will not be helpful.

Magnetic resonance imaging is probably better than ultrasound for diagnosing endometriosis, but it costs more than a thousand dollars a test.

What are the treatments?

Just as there is no definitive theory that explains why endometriosis happens, there is no “cure” that will make it will disappear forever. There are, however, different treatments, some of which deal with the pain that accompanies the disease and some of which focus on reducing or getting rid of the endometrial implants.

Are there self-help measures that will help with the painful periods caused by endometriosis?

Self-help tactics, similar to those for ordinary menstrual pain or premenstrual syndrome, include dietary and lifestyle measures. They are more likely to be helpful during the early stages of the disease. Remember to exercise, for exercise stimulates the brain to produce endorphins, the body’s natural painkillers and mood lifters. Ibuprofen and other over-the-counter medications can also be useful. If these drugs do not do the job, your doctor can prescribe more powerful nonsteroidal anti-inflammatory medications. Some women need narcotic painkillers such as codeine, or narcotic painkillers combined with other drugs.

What treatments will get rid of endometrial implants?

There are two routes for reducing or getting rid of endometrial tissue outside your uterus: you can use hormonal treatment to shrink the implants, or you can have surgery to remove them. The two approaches can be tried separately or they can be combined. The choice of treatment depends on the severity of your symptoms and your interest in having children in the future.

How do you treat endometriosis when fertility is an issue?

There is no easy answer to this question. One choice is to remove surgically as much of the endometriosis as possible and to repair, if possible, the damage the disease may have inflicted on the uterus, fallopian tubes, and other structures. If your endometriosis has resulted in adhesions that have attached an ovary to the side of your pelvis, or in a large cyst of endometriosis sitting on top of an ovary, surgery can repair these problems and enhance your fertility.

The second choice, obviously, is hormonal therapy. The problem here is that the therapy that shrinks the endometriosis also prevents pregnancy.

Endometriosis: Hormonal Treatment

Endometriosis: Surgical Treatment

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