Many women silently endure years of living with endometriosis, a disease that's not often talked about, dismissing their pelvic pain as normal and believing they are just among the unlucky ones who get really bad periods.

LISTEN UP: Add the new Michigan Medicine News Break to your Alexa-enabled device, or subscribe to our daily audio updates on iTunes, Google Play and Stitcher.

International research indicates there is often a delay in diagnosis, with some women suffering with pelvic pain for as long as 12 years before getting the right diagnosis.

Endometriosis affects an estimated 1 in 10 reproductive-aged women, or nearly 200 million worldwide. The inflammatory disease includes tissue growth outside the uterus and may severely disrupt a woman's quality of life and ability to have children.

But despite its high prevalence, research in endometriosis remains underfunded. As such, there have been few improvements in diagnosis and treatment over the past few decades.

Now, experts are calling for that to change.

A group of researchers and clinicians who came together through the Society for Women's Health Research outlined major research gaps and unmet needs of women with endometriosis that have stalled progress in treatment. Their review was recently published in the American Journal of Obstetrics and Gynecology.

"Education and research funding are desperately needed to advance the science and improve care for women who suffer from this debilitating disease," says lead author Sawsan As-Sanie, M.D., MPH, a gynecological surgeon specializing in endometriosis and minimally invasive surgery at the University of Michigan's Von Voigtlander Women's Hospital.

"It is unfortunate that a condition that negatively impacts millions of women's physical and emotional well-being, quality of life and productivity remains so poorly underfunded and under-researched," she says. "Minimal investment in this area has significantly limited our understanding of the disease and slowed progress in treatment."

Symptoms of endometriosis may include pain before and during periods, fatigue, painful bowel movements and painful urination, especially during menstruation. About a third of patients with endometriosis are infertile, and more than half experience pain during sex.

The condition is thought to explain 50 to 80 percent of cases of chronic pelvic pain in women.

As-Sanie has traveled across the globe to communicate the urgency for investing in research to improve treatment, giving keynote presentations at academic and medical conferences in Dubai and Australia just this year.

As-Sanie answers more questions about endometriosis below.

What causes endometriosis?

As-Sanie: We know that this is an estrogen-dependent condition associated with local and systematic inflammation. There appears to be a genetic component, and it tends to affect reproductive-aged women. Studies in baboons, which have spontaneous endometriosis similar to humans, also suggest this is a progressive disease, with periods of regression. However, experts don't believe this to be consistently true in humans, with signs of progressive disease symptoms in about one-third of women with endometriosis.

MORE FROM THE LAB: Subscribe to our weekly newsletter

But there are major gaps in research on the underlying biology of the condition that would help us predict occurrence, explore preventive interventions or enable new therapies.

How is endometriosis diagnosed?

As-Sanie: There is often a significant delay from the onset of patient symptoms and time of diagnosis (anywhere from one to 12 years). A major contributing factor is that diagnosis requires surgical evaluation, and there are currently no available blood tests to definitely confirm or exclude a diagnosis. Imaging is helpful but only detects advanced disease.

Unfortunately, society has also normalized menstrual pain, and women may attempt to ignore or understate the severity of their symptoms.

If the first-line clinician who sees the patient when symptoms begin is not trained in the evaluation and management of pelvic pain, this may also delay a diagnosis. Indeed, more than half of endometriosis patients had been told by health care providers that nothing was wrong with them, according to the Endometriosis Association's research registry. This is a major concern.

More education is clearly necessary to help women and providers identify symptoms of endometriosis earlier and then look for physical clues through a pelvic exam, ultrasound, MRI or laparoscopy, which involves a tiny incision near the navel to insert a viewing instrument to learn about the location and size of endometrial tissue.

What are the biggest problems with treatment?

As-Sanie: Current treatment options are limited to medical therapies that suppress estrogen or surgery to remove lesions in the pelvis, and neither option is effective for all patients. Nor are these permanent cures, since the condition recurs in about 50 percent of women regardless of whether medical or surgical treatment is used.

SEE ALSO: Plotting the Downward Trend in Traditional Hysterectomy

For the last two decades, there have been minimal changes in treatment options due to inadequate funding and research in this area. But with aggressive research, we have hope to change this. There are many inflammatory pathways that have yet to be targeted — presenting great opportunities to further research and move the needle in treatment.

What are the greatest burdens of the disease?

As-Sanie: Endometriosis places significant economic and social burden on patients, their families and society. This is a condition that may negatively impact all aspects of a patient's daily life, including sexual health, appetite, exercise, sleep, emotional well-being, social activities, child care and the ability to have children.

Nearly 95 percent of women with endometriosis also report at least one or more comorbid disorders, such as migraine, depression, anxiety, irritable bowel syndrome, painful bladder syndrome, chronic fatigue syndrome, fibromyalgia, uterine fibroids and ovarian cysts. Endometriosis is also associated with a slight increased risk for several types of cancer (ovarian cancer and cutaneous melanoma), systemic lupus, rheumatoid arthritis and cardiovascular disease.

Total workplace productivity loss averages 6.3 hours per week, with the majority of that loss due to absenteeism, while total household productivity loss averages 4.9 hours per week.

What are the goals of this review?

As-Sanie: The Society for Women's Health Research convened an interdisciplinary group of experts, researchers, clinicians and patients for a roundtable meeting to review the current state of the science on endometriosis and identify areas of need. Stigma surrounding the disease and societal normalization of women's pain continue to stand in the way of timely and accurate diagnosis and effective treatment. This team of experts concluded that a lack of research has also slowed much-needed innovation in diagnostic and treatment options.

SEE ALSO: Will Uterine Fibroid Surgery Become Obsolete?

As a field and as a society, we need to do better. Currently, medical and surgical therapies focus on treating lesions but often don't address the negative impact endometriosis may have on a woman's quality of life.

We owe it to women, their families and communities to invest in research that will expand our knowledge of endometriosis, improve education to prevent delays in diagnosis, increase access to quality care and develop new ways to treat and even prevent the disease in the future.