10 Facts About Endometriosis

Eye-popping pain. Bloating. Heavy periods. Infertility. These are all symptoms of endometriosis, a chronic ailment that is believed to affect up to one in 10 women between the ages of 15 and 49. It can also take a serious toll on patients' mental health. Here's what you need to know about this condition.

1. THE NAME DOESN'T REVEAL MUCH ABOUT THE CONDITION.

Endometriosis, or endo, for short, gets its name from endometrium—the thin layer of tissue that lines a woman's uterus. "Endo is a condition in which endometrial-like tissue grows outside of the uterus, typically in the pelvic area," says Kristin Patzkowsky, M.D., an assistant professor of gynecology and obstetrics at the Johns Hopkins University School of Medicine. Common sites for endometrial growths, called lesions, include the ovaries, fallopian tubes, outer surface of the uterus, and the ligaments and other tissues that hold the uterus in place. The number of lesions can vary and range in size from a few millimeters to grapefruit-size.

2. DOCTORS AREN'T SURE WHAT CAUSES ENDOMETRIOSIS.

The most widely accepted view is that endometrial tissue relocates to other parts of the body during a woman's period. Here's a quick review of the female reproductive cycle: Each month, under the influence of the hormone estrogen, the endometrium thickens and swells in preparation for a potential pregnancy. If pregnancy doesn't occur, the endometrium sheds and flows out of the body. This bloody discharge is menstruation, commonly known as a period. But sometimes menstrual blood flows backward, passes through the fallopian tubes, and enters the pelvic cavity—what doctors call retrograde menstruation. This backward flow can carry endometrial tissue to places far afield of the uterus, such as the digestive tract, lungs, and even the brain. It's been proposed that these transplants set up shop in their new locations, where they continue to respond to the cyclical influences of estrogen by swelling and bleeding each month, and causing the pain associated with endo.

There's an issue, though: Almost all women experience retrograde menstruation, so according to Patzkowsky, doctors don't know why some get endo and others don't. Some researchers think an imbalance in reproductive hormones might be to blame, while others suggest that a faulty immune system—which would normally curb the growth of endometrial cells outside their normal locale—may be responsible. Risk factors for endo include long periods (more than seven days), short cycles (less than 27 days), and having a family member who has endo.

3. PAIN IS A CLASSIC SYMPTOM …

Some women with endo feel pain in the back or chest, and others experience discomfort during or after sex or have painful, heavy periods. Since the pelvic region serves as a crossroads for a variety of organ systems, discomfort when urinating or having bowel movements is common. Some endo sufferers have a concurrent—but not the same—condition called adenomyosis, in which endometrial tissues grow into the muscular wall of the uterus. Endo can also cause large painful cysts on a woman's ovaries, called endometriomas. Often called "chocolate cysts," due to their dark, chocolatey appearance, endometriomas are noncancerous, fluid-filled growths that typically form deep within the ovaries. Mysteriously, some women experience no pain at all, Patzkowsky says. One study found that nearly 90 percent of women with endo experience depression and anxiety. According to some mice studies, it's possible that endo reprograms the brain, making women more vulnerable to mental health problems—although other researchers think the depression and anxiety are more to do with the pain and fertility problems.

4. … AND SOME WOMEN CAN EVEN EXPERIENCE INFERTILITY.

As many as half of all infertile women have endo, and up to 50 percent of women with endo are infertile—but doctors aren't sure how the condition affects a woman's ability to get pregnant. Endo lesions can block or scar a woman's reproductive organs, making it harder for the egg and sperm to meet up, but it's also possible that the scarring prevents the endometrium from developing properly each month, preventing implantation. Other theories suggest that the inflammatory milieu that accompanies endo creates an unfavorable environment for pregnancy.

5. MANY WOMEN WITH ENDO GO UNDIAGNOSED.

Up to one in 10 of all pubescent girls and women worldwide have endo. In the U.S., that translates to some 6.5 million females of reproductive age. Some experts say the number is higher because many women go undiagnosed. That's because some women confuse the pain of endometriosis with normal period pain, and others just don't talk about it. On the other hand, "Not all menstrual pain is endo," Patzkowsky says.

6. THERE ARE SEVERAL WAYS TO LOOK FOR ENDO, BUT ONLY ONE WAY TO BE SURE.

The first step is usually a pelvic exam. The doctor will feel for cysts or areas of scar tissue behind a woman's uterus, in an area called the Pouch of Douglas, a common site of endometrial lesions. If the doctor suspects endo, an ultrasound or MRI will often provide more information. The only sure way to diagnose endo, however, is laparoscopy with biopsy—a minimally invasive surgical procedure that allows a doctor to view a woman's internal organs using a small camera and take tissue samples (biopsies) for testing. Laparoscopy is considered the gold standard of endo diagnosis.

Diagnosis also involves determining the stage of the disease based upon the location, size, and depth of the lesions; the presence and size of endometriomas in the ovaries; and the presence of scar tissue. Most women have mild scarring and only superficial lesions, indicating that they have minimal or mild endo. Women with endometriomas and more severe scarring have moderate or severe endometriosis.

In an odd twist, "The stages don’t necessarily correlate with the types of symptoms or degree of pain a woman experiences," Patzkowsky says. For some women, a further element of diagnosis is determining her likelihood of getting pregnant, using the Endometriosis Fertility Index [PDF], a scoring system that considers a woman's age, reproductive and infertility history, and endo severity to predict her chances of conceiving.

7. TREATMENTS AIM TO REDUCE THE SIZE OF THE LESIONS.

If a woman with endo doesn't want to get pregnant, her doctor might prescribe hormonal treatments to reduce the amount of estrogen in her body. Extended cycle and continuous cycle birth control methods reduce or eliminate the number of periods a woman has, blocking the cyclical effects of estrogen. If pregnancy is the goal, however, a woman's doctor might briefly prescribe gonadotropin-releasing hormone agonists—hormone-blocking drugs that induce a sort of temporary menopause that stops a woman's production of estrogen and can often decrease the size of endo lesions. The treatment period typically lasts several weeks to a few months. When the treatment ends, the woman's body will begin to produce estrogen again, providing her a brief window of time in which she has a chance of getting pregnant before the lesions return.

Surgery to remove endo lesions is also an option, but only in severe cases or in situations when a woman can't take hormonal therapies or hormones haven't been successful in the past.

8. ENDO IS COSTLY, AND NOT JUST IN DOLLARS.

Quality-of-life assessments don't accurately capture the toll endo takes on women: Findings from a 2011 study of more than 1400 women with endo found that women lost more than 11 hours of work each week chiefly due to reduced productivity (not absence). A second study, conducted in 2012, estimated that endo costs an affected woman more than $10,000 per year, comparable to diabetes, Crohn's disease, or rheumatoid arthritis. Endo also interferes with sexual pleasure and satisfaction.

9. AN ENDO DIAGNOSIS DOESN'T HAVE TO FEEL LIKE THE END OF THE WORLD.

Many women with endo lead full lives. Northern Irish politician Naomi Long and Australian swimmer Emily Seebohm, an Olympic gold medalist, have shared their personal trials with the condition. Women with endo get pregnant, too, and often have successful pregnancies. "Endo does not equal infertility," Patzkowsky says. Women with endo often find that support groups are helpful, and there's even an app (or two) to help. One advocacy group has organized a worldwide endo march to raise awareness of the disease and promote research.

10. NEW ENDO RESEARCH IS FOCUSED ON IDENTIFYING BIOMARKERS.

Future endo research is focused on not only furthering understanding of the causes and other aspects of the disease, but also on developing non-hormonal therapies to aid in treatment and identifying biomarkers—indicators in blood or easily accessible tissue samples—that can speed diagnosis. Some scientists liken endo to cancer because it has different subtypes that may have different causes, requiring an integrated approach to understanding the genetic, hormonal, metabolic, and molecular factors that influence endo development and progression.