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One of the most common gynecological diseases, endometriosis often goes undetected for years because the abdominal pain associated with the condition is mistaken for menstrual cramps, or because there may be no symptoms. On average, women in the United States will suffer from endometriosis for 10 years before receiving a proper diagnosis. 

Endometriosis affects one in 10 women, and many women who report chronic pelvic pain are found to have it. The condition affects up to half of women who are infertile. At the Yale Medicine Fertility Center, clinicians take endometriosis very seriously and work closely with patients to accurately screen for and diagnose the disease.

Women come to us from around the country to seek treatment from our experts in endometriosis. "We are involved in clinical trials to bring new drugs to market that could be useful, in addition to developing a blood test to detect the disease," says Yale Medicine's Hugh Taylor, MD, chair of obstetrics, gynecology & reproductive sciences. "We are at the forefront of diagnosing and treating this disease, from which many women suffer in silence for years." 

What is endometriosis?

Endometriosis occurs when the normal lining of the uterus starts to grow outside the uterine wall. It may spread to the ovaries, fallopian tubes, uterus, bowel or bladder, or anywhere inside the abdominal cavity.  

In most cases, the abnormal uterine lining will shed when a woman starts her period, which leads to bleeding, inflammation and scarring inside the pelvic cavity. 

Often, endometriosis causes pain far greater than would be expected during a normal menstrual cycle, but even in cases where no pain is experienced, the condition can lead to organ damage, internal scarring and infertility.

"It is a progressive disease. If we can catch it early, we can stop it from spreading and causing scarring and adhesions," Dr. Taylor says, adding that this is important because once scarring occurs, hormonal treatments and even surgery may not help.

Making women aware of symptoms is crucial, he says, because a proper diagnosis and treatment can make a huge difference in a woman's life.

"Endometriosis can often start during the teenage years or when a woman is in her 20s, which are formative years in her life," Dr. Taylor says. "If you are young, and in school or just starting your career, being disabled from pain can stop women from reaching their full potential, which is a shame." 

What are the risk factors for endometriosis?

Scientists have not found a single cause for endometriosis, but a few factors may increase the risk of developing the condition. 

These include:

  • Family history: Women with female relatives who have had endometriosis are more likely to develop it themselves.
  • Never having been pregnant: Because pregnancy will sometimes reduce the symptoms of endometriosis, women who have never been pregnant are at a higher risk. 
  • Retrograde menstruation: This occurs when monthly discharge that would normally leave the body through the vagina flows backward into the fallopian tubes. Nearly all women experience a small degree of retrograde menstruation, yet only about 10 percent will develop endometriosis. In these cases, small pieces of endometrial tissue may grow inside the abdominal cavity. Experts at Yale are working to understand why some women develop endometriosis under these circumstances, while others do not. 

What are the symptoms of endometriosis?

Pelvic pain is the primary symptom. Because pelvic pain can be attributed to many different diseases, such as irritable bowel syndrome and other inflammatory diseases, the symptoms of endometriosis are often misdiagnosed. 

The condition is also commonly overlooked or downplayed as “normal” period cramps among young women. Pain that increases over time and varies through the menstrual cycle is often endometriosis.

"We think cases of endometriosis are under-reported because it is often dismissed as something normal," Dr. Taylor says. "If a young girl has painful periods and she tells this to her mother, her mother might just say, 'Cramps are supposed to hurt. That is our lot in life.'"

In the past, there were social taboos that often stopped women of prior generations from discussing their periods or painful sex, which could also delay diagnosis and treatment. "But that is changing now," Dr. Taylor says. 

Does endometriosis affect fertility?

Many women with endometriosis have questions about their ability to become pregnant. Having endometriosis does not mean you will be unable to have children, but it may make the process more difficult. 

Women with mild endometriosis who never seek treatment become pregnant on their own at a rate of 2 to 4.5 percent per month, compared to a 15 to 20 percent fertility rate in women without endometriosis.

Laparoscopic surgery is the best option for women who want to manage pain and boost their chances of becoming pregnant. In one study, 29 percent of women with endometriosis who had laparoscopic surgery were able to become pregnant within nine months, compared to 17 percent of women with the condition who were not treated. However, if pain is not present, there are often other ways to help a woman with endometriosis conceive.

How is endometriosis diagnosed?

Some women with endometriosis do not experience pain and are diagnosed only if a doctor happens to notice abnormal tissue during a different procedure, such as tubal sterilization. While certain symptoms like pelvic pain may point to endometriosis, the only way to know for sure is to conduct a laparoscopic surgical procedure in which a small telescope is inserted inside the abdomen through the belly button. This allows the physician to observe and surgically remove the endometriosis if necessary. 

Unless the disease is particularly bad, endometriosis will not be visible on any imaging tests, Dr. Taylor says. 

"The gold standard has been to diagnose through surgery, but that has been a barrier for women. Today, there is a push, which I have championed, to make a clinical diagnosis and start treatment,” he says.

Furthermore, Yale researchers have developed a new blood test to detect endometriosis. 

In the meantime, Dr. Taylor emphasizes that women should pay attention to pain that is progressive and "cyclical," or always comes at the time of their menstrual period. "If it varies with your menstrual cycle and you have painful menstruation and cramps and bowel pain, it will likely be endometriosis," he says. "But if you've had horrible periods since you were 12 and it has never changed, not necessarily." 

Plus, a 13-year-old girl who is exhibiting symptoms of endometriosis doesn't always warrant a pelvic exam. "That is sometimes what keeps younger women out of our office. But we can make a diagnosis just by talking to them or by palpating the abdomen."

What medical treatments are used for endometriosis?

Our clinicians work closely with you to understand your goals for pain management and fertility. Medical therapy generally involves altering the hormones that cause the growth of the endometrium and spread of these cells within the abdomen. These medications may be used on their own or after surgery to prevent recurrence of the disease. 

Options include:

  • Oral contraceptive pill: This is often the first treatment attempted. The pill can suppress the period and stop mild to moderate endometriosis from progressing while addressing the pain. The combined oral contraceptive can be given in a fashion that completely eliminates menstruation, and therefore stops painful periods. For women who don't plan to conceive immediately, this may be a good option. 
  • Progestin: If oral contraceptives do not work or if there are side effects, often a progestin is given as a second-line therapy. Progestin also inhibits estrogen and the growth of the endometrium. These pills are given orally and often are more effective than oral contraceptives at relieving the symptoms of endometriosis. They may have more side effects than an oral contraceptive, but less than some other medications. 
  • Danizol: A hormone derived from the male hormone testosterone, it also can be very effective at reducing endometriosis. However, because of its male-like hormone, there may be unwanted side effects such as hair growth or acne. 
  • Gonadotrophin-releasing hormone agonists: Also known by the brand name Lupron, these hormones stop the production of estrogen and progestin and are highly effecting at relieving endometriosis. They are given by injection. 

At Yale Medicine, our researchers are involved in clinical trials for new medications to treat endometriosis. 

What are the surgical options for endometriosis?

For some women, drug treatments might not be enough and surgical options may be explored.

Surgery is often used to restore the function of any damaged organs, removes scarring and adhesions, and alleviate pain. It is very successful in both relieving the symptoms and improving pregnancy rates. Unfortunately, even though the disease is removed, its underlying cause has not changed and it will likely recur over time. 

"Fifty percent of surgical patients will have a recurrence in two years unless we keep them on medication after surgery to help avoid that," Dr. Taylor says. "But endometriosis will go away on its own after menopause." 

In severe cases of endometriosis, surgeons should be prepared to remove endometriosis from the bowel or bladder. Most women will be able to have a laparoscopic procedure (a minimally invasive surgery with small instruments placed through incisions that are approximately ½ inch long in two to three areas of the abdomen). The surgeon excises the endometriosis. Most women will go home on the same day as the operation and will generally take between five to seven days to recover.

In rare cases, the disease is so severe that a laparoscopy may not be possible. A full incision called a laparotomy may be required. This operation requires a larger open incision and several nights in the hospital as well as a longer recovery time. Unless the disease is very advanced this is unlikely to be necessary. 

A hysterectomy should be reserved as a last resort in extreme cases and only after a woman has indicated that she has completed her family.

What makes Yale Medicine's approach to treating endometriosis unique?

Our researchers are at the forefront of looking into the root causes of endometriosis, including how genetic factors play a role.

"We are developing a blood test to diagnose as well as personalized medical treatments that look at the disease on a molecular basis and allow us to tailor our care," Dr. Taylor says. "Plus, with a large academic center behind us, we have gastro-intestinal and urologic surgeons and other specialists ready to help. Having medical and surgical options allows women to weigh all of their choices at once."