That good ole time of the month.

There is nothing we can do to change it, but for some women, this time is accompanied by severe pain that is associated with a condition called endometriosis

Although endometriosis has received a lot of press lately, with multiple celebrities opening up about their struggles with the disease (Halsey, Lena Dunham, Chrissy Teigen, Whoopi Goldberg, and more) awareness of it remains low.

What is endometriosis and how is it caused?

The endometrium is a layer of tissue that lines the uterus and is the site of attachment for a fertilized egg, which will eventually develop into an embryo. Every month, as part of the menstrual cycle, the endometrium thickens in preparation for these early stages of pregnancy. If pregnancy does not occur, the endometrium breaks down and is shed in the process of menstruation.

Endometriosis is a condition that is caused when endometrium-like tissue is found outside of the uterus, often as small lesions attached to the outside pelvic organs like the ovaries, fallopian tubes, or the uterus itself. These lesions are still able to act as the endometrium does, thickening and bleeding with the monthly cycle. However, since these endometrium-like lesions are located in places they’re not supposed to be, this behavior can cause inflammation and pain.

The cause of endometriosis and the mechanism by which endometrial tissue gets outside the uterus is still unclear, but the most common hypothesis is retrograde menstruation, which is essentially the backward movement of menstrual fluid. Instead of exiting the body like it’s supposed to, menstrual fluid can flow in the reverse direction, out of the fallopian tubes, and into the abdominal cavity.

Illustration of endometriosis, endometrial tissue in the uterus, female disease, womens medicine
Endometriosis occurs when endometrial tissue gets outside of the uterus. These lesions thicken and bleed with the monthly cycle, causing inflammation and pain.

Why is it so hard to diagnose endometriosis?

Endometriosis affects approximately 10% (~190 million) of women worldwide. Although endometriosis is not rare, it can have a reputation for being fairly unknown given the historical lack of awareness surrounding it. Additionally, endometriosis is notoriously difficult to diagnose, with an estimated average of seven years to make a diagnosis. 

One of the challenges associated with diagnosing endometriosis is the lack of symptom specificity. Since the main symptom of endometriosis is pelvic pain, it can be difficult to distinguish from other conditions such as inflammatory bowel disease or pelvic inflammatory disease.

Although endometriosis can sometimes be diagnosed using imaging techniques like MRI, a definitive diagnosis of endometriosis is only established with visual inspection via laparoscopy. During this surgical procedure, a small camera is inserted via an abdominal incision to look for and identify endometriosis lesions.

Of note, confirmative laparoscopy may not be a suitable choice for some women and so these cases, along with the estimated 20-25% of asymptomatic cases, may go undiagnosed.

Another challenge in the diagnosis of endometriosis is the assessment of pain. Women are familiar with the concept that menstrual pain is normal, but how to know how much is too much? Or, what type of pain suggests endometriosis? As individual pain symptoms differ widely among women with endometriosis, quantitative assessments of pain using a pain scale may be very difficult to parse due to individual interpretation and the variety of ways an individual might describe her pain. 

Qualitative assessments of pain, focused on understanding how women’s lives are impacted by endometriosis, such as whether endometriosis-related pain prevented one from attending school or work, may prove to be more informative in understanding the impact of this disease on everyday life.

What treatments are available for endometriosis?

The economic burden of health care costs associated with the condition can be high, with a 2008 study estimating a similar cost (including the cost of physician visits and surgical procedures) to that of other chronic diseases such as diabetes and Crohn’s disease. This is in addition to the cost on quality of life caused by severe menstrual pain, which can negatively affect work productivity and other aspects of everyday life. Women with endometriosis can also suffer from pain during intercourse and approximately 30% experience infertility, an estimated rate two times that of women without endometriosis.

There is no cure for endometriosis. Even the most aggressive treatment option does not guarantee success, and many may experience limited benefit from available treatments. Furthermore, most of the treatment options available for women with endometriosis are not available to those wanting to become pregnant, leaving many with few options to relieve the chronic pain.

Hormonal birth control, including oral contraceptive pills and hormone-releasing intrauterine devices, is the most common method for treating endometriosis-associated menstrual pain. However, with a huge catalog of birth control pills to choose from, and certain hormone combinations likely to be more effective than others, a one-size-fits all pill regimen is not practical.

Elagolix is a gonadotropin-releasing hormone antagonist that reduces levels of estrogen, the hormone that drives endometriosis and growth of endometrial tissue. In 2017, results from a phase 3 trial of elagolix (now branded as ORILISSA®) for the treatment of endometriosis were published, demonstrating improvements in endometriosis-associated pain over a 6-month period. Elagolix was approved in 2018 for the management of moderate to severe pain associated with endometriosis, but it has not had a glowing reception. In particular, its critics argue that elagolix offers few benefits over currently available treatments, particularly given its cost ($974.54 list price for a 4-week supply).

There are also surgical interventions for endometriosis. Endometriosis lesions can be targeted during a laparoscopy via ablation (burning with a laser) or by cutting out the lesions directly. Finally, as a more aggressive option, a hysterectomy can be performed. A hysterectomy involves removing the uterus and may include removal of the cervix and/or ovaries. The rationale behind a hysterectomy as an endometriosis treatment is that by removing the endometrium with the uterus, the source of the lesions is also removed. However, even a hysterectomy does not prevent endometriosis recurrence. 


Gynecology and women health. Consultation with a gynecologist or reproductologist. Isolated vector illustration
Treatments for endometriosis include hormonal birth control and surgical interventions.

What’s next for endometriosis?

The choice between severe chronic pain managed with oral contraceptives or surgery and potential surgical sterilization is the choice that women with endometriosis currently face. For those wanting to conceive, the choices are even fewer as most of the available non-invasive interventions are hormone-based, and their regular use is likely (or designed) to prevent pregnancy.

As of the writing of this post, there are 19 active clinical trials for endometriosis in the US, with 157 more planned or recruiting/enrolling. According to a review in the New England Journal of Medicine last year, 15 currently registered clinical trials will focus on non-hormonal treatments for endometriosis with the goal of evaluating new approaches to treatment. This review highlighted the urgent need for better options, stating: 

“Given the high prevalence of endometriosis, the cumulative effect of the disease on health and well-being across the life course, and the high associated economic costs, improvements in awareness, education, and action are long overdue.”

While the clinical world investigates new ways of treating endometriosis, you can help by raising awareness of the disease. Awareness starts by getting comfortable talking about aspects of women’s health that make you uncomfortable. 

Remember, half of the world’s population has had, will have, or currently has a monthly period.