Endometriosis affects an estimated 10 percent of women of reproductive age, and yet the condition remains shrouded in mystery and misconceptions. The endometrium, or the specialized cells that normally line the uterus and are shed during menstruation, can attach and grow at other sites within the body. Typically, the cells adhere to the lining of the abdominal cavity or its organs, such as the colon, bladder, ovaries, and fallopian tubes, although they sometimes lodge farther away, such as in the chest.

Complications arise because the displaced cells still behave as if they were within the uterus, thickening and shedding during menstruation. Over time, the repeated shedding and pooling of blood can cause inflammation and scarring, often resulting in severe, debilitating pain and even infertility.

Though the condition is typically diagnosed in women in their 30s, symptoms begin much earlier—during the teen years.

“This is a frustrating and complex disease, with no known cause or cure,” explains gynecological surgeon Kathy Huang, MD, director of the new Endometriosis Center at NYU Langone. “To help women holistically, we’ve brought together experts in gynecology, reproductive medicine, surgery, radiology, pain management, pelvic floor therapy, and other specialties.” Here, Dr. Huang addresses some common issues regarding endometriosis.

No One Really Knows Why Endometrial Cells Turn Up Outside the Uterus

The most accepted theory is that not all of the cells shed during a woman’s period are expelled from the body. Some may travel backward through the fallopian tubes and into the abdomen, attaching to organs. This process, called retrograde menstruation, may occur in most women, and while many are able to clear the tissue naturally, others are not. Another theory is that some endometrial cells are absorbed into the bloodstream or lymphatic system and are simply carried away to distant sites. The most intriguing hypothesis relies on the potential of one type of cell to transform into another, a phenomenon known as metaplasia. In this scenario, normal cells may be stimulated by attached endometrial cells and the hormones that trigger menstruation to change into endometrial cells themselves. Heredity and a glitch in the body’s immune system may play parts as well.

Diagnosis is Frequently Missed, Especially in Teenagers

Though the condition is typically diagnosed in women in their 30s, symptoms begin much earlier—during the teen years. “Unfortunately, young women are often told that intense pain is a normal burden of menstruation,” says Dr. Huang. “But severe pain is never normal.” Risk factors for endometriosis include a mother or sisters with the condition, and the onset of menstruation at age 11 or younger. “Early diagnosis prevents needless suffering and is the key to preserving fertility, since endometriosis is a progressive disease,” notes Dr. Huang.

Adult women also get dismissed. “They’re often told the problem is all in their heads,” she adds. But even when complaints are taken seriously, diagnosis can lag because the symptoms may be mistakenly ascribed to other conditions, such as fibroids, ovarian cysts, irritable bowel syndrome, a urinary tract infection, or a sexually transmitted disease.

An MRI is Often the Best Way to See Hidden Endometrial Cells

A variety of techniques are used to diagnose endometriosis, including pelvic exams and ultrasound, but it’s hard to spot all the embedded cells. The Endometriosis Center uses magnetic resonance imaging (MRI) because it often provides a clearer view of what’s happening internally. “This helps in assessing the extent of the disease, as well as in planning any surgery,” says Dr. Huang. “We have found that MRI offers 80 percent accuracy as a diagnostic tool for endometriosis.”

Endometriosis Does Not Automatically Doom Women to Infertility

For various reasons, endometriosis seems to hinder fertility. One factor may be the scarring that obstructs the tubes, possibly preventing the sperm from reaching and fertilizing the egg. Nevertheless, women can usually become pregnant. “They just have a harder time and may require more help,” explains Dr. Huang. A study of 4,000 women with endometriosis found that while more than half didn’t conceive within a year of trying, 70 percent did eventually have a child.

Neither Pregnancy Nor a Hysterectomy Can Cure Endometriosis

Pregnancy subdues the symptoms of endometriosis by eliminating the menstrual cycle. But after pregnancy, menstruation resumes, and symptoms will likely reappear. Many people think that by removing the uterus, and thus permanently eliminating the menstrual cycle, endometriosis will be eradicated. Not so. It is the ovaries that produce the estrogen and progesterone that stimulate shedding of the uterine lining, so unless they are removed as well, they will continue to stimulate escaped endometrial cells. While there is no cure, endometriosis is often treated with hormonal therapy to regulate or eliminate the menstrual cycle, or surgery to excise endometrial lesions.