Endometriosis is a disease that occurs when the cells of the tissue lining the uterus (the endometrium) travel to other parts of the body and begin to grow Figure 01. Areas affected by this misplaced tissue may include the ovaries, the fallopian tubes, the area behind the uterus, the area between the vagina and rectum, and the pelvis. The misplaced tissue can also grow on the colon, the wall of the abdomen, the appendix, and the lungs.
Figure 01. Female reproductive anatomy
Misplaced tissue, like the uterine lining, reacts to the hormones estrogen and progesterone during the menstrual cycle. Each month, the misplaced tissue builds up to prepare for implantation of an egg. However, as these tissue cells are shed, they have no way of exiting the body. This means that they can build up over time to form lesions, masses, and bands of scar tissue (called adhesions).
Areas where misplaced tissue collects often become inflamed and swollen, are tender to the touch, and can be extremely painful.
Endometriosis tends to be a progressive disease, which means that symptoms usually get worse over time. However, there are no adequate long-term studies of the progression of endometriosis to truly say that is it gets worse in most women.
Endometriosis is usually confirmed and treated by a gynecologist. Your primary care doctor, however, is often the first to recognize endometriosis. A team of specialists, including an endocrinologist and a surgeon, may also become involved in your care.
Experts are not exactly sure what causes endometriosis Table 01. The cause of endometriosis is not known. Many medical researchers believe that it is due to a process called “retrograde menstruation.” In this process, small amounts of blood and tissue flow backward into the fallopian tubes during menstruation. From there, they leak out and begin to grow in the pelvis and abdomen. This process occurs in almost every woman, but certain women have weaknesses in their immune systems that interfere with their bodies' ability to expel the blood and tissue fragments. Another theory suggests that uterine tissue is carried through the blood vessels or lymphatic system to distant organs, where it implants itself and grows. Studies also show that endometriosis is common in women with a family history of the disease. In addition, if a woman has a first-degree relative with endometriosis, she has a higher risk for more severe disease. Finally, a more controversial theory suggests that endometriosis is caused by exposure to environmental toxins, mainly dioxin, which is a by-product of pesticides, bleached pulp and paper products, and the burning of medical or municipal waste.
Table 1. Possible Causes of Endometriosis
Cause What happens Backflow of blood and tissue into the fallopian tubes during menstruation (retrograde menstruation) Blood and tissue fragments may begin to grow in the pelvis and abdomen after flowing back through the fallopian tubes. Certain women are thought to be more vulnerable to this process because their bodies are unable to expel these fragments naturally. Distribution of uterine tissue through the blood vessels or lymphatic system Misplaced uterine tissue may travel through the blood vessels or channels of the body's lymph system to distant organs (including the abdomen, lung, and lymph nodes in the pelvis). It then attaches itself and begins to grow. Genes The gene for endometriosis may be inherited through the mother. Having a twin sister with the disease also increases risk Environmental toxins Studies in monkeys suggest that long-term exposure to the pesticide dioxin leads to endometriosis. Some studies in women with endometriosis have shown higher levels of dioxin in their bloodstream compared to women without endometriosis.
Symptoms of endometriosis, such as pain in the lower abdomen, crampy pelvic pain, and pain during intercourse, are unpredictable Table 02. Symptoms of endometriosis differ among women, and can also change over the course of the disease. As many as 30% of women with endometriosis never have any symptoms. However, three types of pain have been described. The first is lower abdominal and deep pelvic pain that continues throughout menstruation. This crampy pain usually starts about two days before the menstrual flow and lasts for several days afterward. The second type of pain is deep, crampy pelvic pain that lasts throughout the cycle; it usually occurs in women with severe endometriosis. Although most women experience some kind of cramping while they are menstruating, crampy pain associated with endometriosis is usually more severe. The third type of pain, pain during intercourse, worsens on deep penetration, and can be triggered by specific sexual positions; it can also worsen during menstruation.
Endometriosis sometimes causes symptoms that seem to be unrelated to the disease, such as difficult bowel movements, painful urination, and shortness of breath. If the colon or stomach is involved, bowel movements may be difficult and painful. There may also be blood in the stool. Likewise, endometrial tissue in the urinary tract can cause blood in the urine or pain while urinating. In the lungs, endometriosis can cause coughing, shortness of breath, and chest pain. Tissue can grow on abdominal scars and cause tenderness and swelling. Sometimes misplaced tissue even grows within the nerves that connect the brain and spinal cord to other organs; this may cause sciatica (pain that begins in the lower back and travels down the back of the thighs) and headaches during menstruation.
The most worrisome symptom of endometriosis is infertility, although the two conditions may not be linked. While there is no evidence that endometriosis directly causes infertility, some 20% to 50% of infertile women have endometriosis. There is no clear explanation for this, although scarring and damage to the reproductive organs may play an important role.
The severity of endometriosis pain depends on where lesions and scar tissue are located, and how far they extend. Pain tends to increase the longer endometriosis goes unrecognized and untreated. Keep in mind that pelvic pain and abdominal pain can have other causes, especially if they do not occur around the menstrual cycle. These causes include tubal pregnancy, urinary tract infection, irritable bowel syndrome, colitis, Crohn's disease, an inflamed fallopian tube, a ruptured ovarian cyst, and scarring behind the uterus and on the walls of pelvis (pelvic adhesions).
Table 2. Symptoms of Endometriosis
Low abdominal or deep pelvic pain that starts two days before menstrual flow and lasts several days afterward. Described as aching, dull, and crampy, spreading to back and thighs. May also cause nausea, diarrhea, and pressure in the rectum. Same as above but lasting throughout the entire cycle Pelvic pain that occurs during vaginal intercourse, especially during deep penetration or during specific positions. Usually worst just before the menstrual flow but may last throughout the cycle Infertility Difficult, painful bowel movements Blood in stool Pain during urination Blood in urine Coughing Shortness of breath Chest pain Sciatic pain Headaches around the menstrual period Pain, tenderness, or swelling in or around abdominal scars, usually associated with menstruation
Endometriosis mainly affects women in their reproductive years (between the ages of 15 and 44) Table 03. Although the exact numbers are unknown, about 10% of women between the ages of 15 and 44 (approximately 5 million women) are affected by endometriosis. Certain factors appear to increase risk. For example, endometriosis is more common in women with shorter menstrual cycles (<27 days), longer menstrual flow (>7 days), and spotting before their periods begin. It is less common among women who have had at least one pregnancy, although this protection seems to decrease as the time between pregnancies increases.
Endometriosis also appears to be related to estrogen levels. Estrogen is responsible for the thickening of the uterine lining during the menstrual cycle. Some lifestyle factors seem to reduce the risk for endometriosis by reducing estrogen levels. For example, exercising regularly and maintaining a lower percentage of body fat ratio seem to reduce risk because they lower the amount of estrogen circulating in the body at any given time.
A family history of endometriosis increases risk. Endometriosis is inherited through the mother. Also, studies show that a woman who has an identical twin with endometriosis is four times more likely than a woman in the general population to have endometriosis herself. For nonidentical twins, the risk is twice as high.
Table 3. Factors Affecting Risk for Endometriosis
Increases risk Menstrual periods >7days Menstrual cycle <27 days Spotting before the menstrual period begins Increased estrogen levels in the blood Having a mother with endometriosis Having an identical twin with endometriosis (quadruples the risk) Having a nonidentical twin with endometriosis (doubles the risk) Decreases risk A previous pregnancy Exercise A low body fat ratio
Your doctor will take a detailed medical history to help determine whether you have endometriosis, and to rule out other possible illnesses. Details about your symptoms, including when they first started, how long they last, and where in the body they occur, can help to confirm or rule out endometriosis. Severe symptoms that occur suddenly usually indicate another type of illness.
A physical examination can sometimes help your doctor locate definite signs of endometriosis. Physical examination findings are normal in about 50% of women with endometriosis. Other times, the doctor may find nodules and tissue masses on the upper part of the vagina, on the back of the uterus and cervix, and between the rectum and vagina. These may be tender when touched. The uterus may also be tilted upward because of scarring behind the uterus and on the pelvic walls.
The only way to confirm endometriosis is through a procedure called laparoscopy Figure 02. There are no laboratory or blood tests that are sensitive enough to diagnose endometriosis. Your doctor may use imaging studies, such as ultrasonography or magnetic resonance imaging, to look at tissue masses felt during the physical examination and to determine which areas of the body are affected. However, the only way to absolutely confirm a diagnosis is by performing laparoscopy. In this procedure, a microscope-like, tube-shaped instrument is inserted into the abdomen just below the navel. Laparoscopy can be done in the hospital or in an outpatient setting, and is usually reserved for women who do not respond to treatment of their pain.
Figure 02. Laparoscopy
Prevention and Screening
- Common Side Effects of AntidepressantsFind out about common and not-so-common side effects of antidepressants and how to manage them.
- How Drugs Can Lower CholesterolDiscover how cholesterol-lowering medications work in your body to bring your cholesterol numbers down to ideal levels.
- Do Over-the-Counter Proton-Pump Inhibitors Work?You might wonder why you need a prescription for GERD if many PPIs are available over the counter. Get the answers to this and other questions about OTC PPIs.