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Endometriosis 101

Top things to know:

  • Endometriosis is a disorder where endometrial-like tissue (like that which lines the uterus) is present in other parts of the body

  • Endometriosis is a leading cause of pelvic pain and painful sex

  • Until endometriosis is better understood, only the symptoms can be treated, and not the underlying causes

  • Management options include medications, surgery, and possibly lifestyle changes

What is endometriosis?

Endometriosis is a common disorder in which endometrial-like tissue grows where it isn’t meant to be. Endometrial tissue is the tissue that grows and sheds in the uterus. In most cases, this growth happens on and around organs in the pelvic cavity. The tissue in endometriosis acts similarly to that inside the uterus: it grows, thickens, and tries to shed with every menstrual cycle. Since the tissue has no way of leaving the body, it can cause adhesions, nodules, and lesions which trigger an inflammatory response (1). This can lead to pain and other complications, like infertility (2).

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Endometriosis may affect about 1 in 10 women of reproductive age, though estimates vary widely and prevalence probably differs across populations (2, 3). Incidence may be lower in black and hispanic women, for example (4).

It can be a difficult condition to diagnose early, because many people don’t have symptoms, and because confirming a diagnosis requires a surgical procedure. Others have symptoms for years, and visit several doctors, before being diagnosed (5). If you think you could have endometriosis, tracking your pain, bleeding and other symptoms in Clue can provide your healthcare provider with information that may help with diagnosis and in forming a treatment plan. Early treatment can reduce the risk of complications.

What you might notice

The symptoms of endometriosis can begin in early adolescence, or show up later in adulthood (6). Symptoms may occur at all times, or may be cyclical. Cyclical symptoms come and go around the same time each menstrual cycle, often occurring around the same time as menstruation. The symptoms and impact of endometriosis can vary based on where the tissue is located. Ovarian endometriosis, for example, is one type that can cause infertility. The stage of advancement of the endometriosis doesn’t appear to correlate with the severity of symptoms (7).

Common symptoms of endometriosis include:

  • Premenstrual/menstrual cramps that are very painful

  • Pain during or after sex (dyspareunia)

  • Painful bowel movements and/or urination

  • Pain in the abdomen, lower back, or thighs often lasting throughout the cycle

  • Heavy periods

  • Difficulty becoming pregnant (infertility) (8-11)

Endometriosis can begin around the same time as the first period (*menarche*). This can lead a person to think a high level of pain is “normal” for them, when it may actually be caused by endometriosis or by another medical condition (5-6).

If you’re questioning your menstrual pain, talk to your healthcare provider to see if endometriosis might be a factor.

What causes endometriosis?

The reasons why endometrial-like tissue grows where it does in endometriosis are unknown. It was originally thought that it was caused by uterine tissue flowing back through the fallopian tubes into the pelvic cavity (ie. retrograde menstruation), but up to 9 in 10 people have retrograde menstruation, and most do not develop endometriosis, suggesting the involvement of other factors (12, 13).

Also, some girls develop the condition before they reach menarche (6). One theory is that endometriosis could develop from endometrial cells traveling through blood vessels or the lymphatic system (14). Another is that cells outside of the uterus might develop into endometrial cells (15). In premenarchal endometriosis, it’s been suggested that exposure to maternal hormones, and neonatal uterine bleeding play a role (16, 17). Excess estrogen, genes and the immune system may all play a role in the development of this condition (14,18-21). There is evidence that endometriosis can be passed down through families (21-23). This means a person may be more likely to have it if someone in their biological family does, too. Someone may also be more likely to develop endometriosis if they give birth later in life or not at all, if they have an earlier age at menarche or late menopause, or if they have short menstrual cycles (< 28 days) (22-24). This may be because they have had more menstrual cycles on average, and more exposure to estrogen. Some research shows that people with endometriosis also tend to have higher overall inflammation in the body, higher levels of “bad” vs. “good” fats in the blood (low-density lipoproteins vs. high-density lipoproteins) and higher levels of oxidative stress (25-28). Oxidative stress refers to the level of damage in the body’s cells, tissues and organs from things such as environmental toxins or by-products of our metabolism. It’s not yet understood why these characteristics often appear in people with endometriosis, or what the underlying causes are.

Why get it checked out

Endometriosis is typically a progressive condition, meaning it can get worse over time (29). Infertility is a common complication of endometriosis that may be avoidable with early treatment. Up to half of those with endometriosis have decreased fertility (30). Recent research has also found that people with endometriosis may be at higher risk of cardiovascular problems including heart disease and heart attacks (25). This could be due to the levels of inflammation, fats, and oxidative stress seen in many people with endometriosis. Early diagnosis can improve outcomes down the road. Early management can help reduce progression of the condition, reduce complications, and keep symptoms under control.

How endometriosis is diagnosed

Many people with endometriosis are treated based on their symptoms, without a formal diagnosis. In other cases, an official diagnosis is done via a laparoscopy, a simple surgery. In this procedure, doctors make a small incision in the abdomen (usually under 1.5cm/0.6 inches) and insert a camera to look inside the pelvic cavity. Small tissue samples may be collected, called biopsies.

A healthcare provider will probably ask questions about your medical and menstrual history and perform a simple physical exam. They will want to hear about pain symptoms and any issues with infertility or miscarriage. If the healthcare provider thinks endometriosis may be present, they may also perform:

  • A pelvic exam

  • A pelvic ultrasound (sonogram)

  • A laparoscopy

It can be helpful to monitor your pain level and share this information with your healthcare provider. While some discomfort around menstruation is considered “normal,” pain in endometriosis can be much worse, and it's important to communicate what feels true for you (5, 31). You might also try talking to someone who specializes in gynecology or endometriosis. Being an advocate for oneself may help minimize the time it takes to get a diagnosis in people with the condition. It’s not uncommon for a diagnosis to take ~5 years (or between 3-11 years) after the onset of symptoms (5, 32).

What are the treatment and management options for endometriosis?

Endometriosis usually lasts many years, but the symptoms are manageable with treatment. Until endometriosis is better understood, only the symptoms can be treated, and not the underlying causes.

How endometriosis is treated will depend on the symptoms and goals of each person. Goals might be to feel less pain, or to become pregnant. Many people’s symptoms are mild enough that they choose not to have treatment at all, but endometriosis should still be monitored as it can cause issues down the road.


If someone experiences pain from endometriosis, a healthcare provider will often suggest a NSAID — an over-the-counter pain medication. Hormonal medications are also often prescribed as an early approach (33). Other medications that affect the hormones may also be prescribed if first-line approaches are not sufficient: GnRH antagonists prevent ovulation and may stop the thickening and shedding of some endometrial tissue (33, 34). Aromatase inhibitors limit the body’s production of estrogen, and may help with some symptoms, but can cause strong side effects and are usually prescribed after other options have been explored (33, 35).


In some cases, a doctor might suggest a laparoscopy to explore and surgically remove or destroy problematic tissue. This can help with symptoms, and improve fertility (36). Doctors may perform laparoscopic excision or ablation. Excision consists of cutting away problematic tissue, while ablation consists of burning away the tissue through cauterization or a laser.

There is a lot of debate about which method is better for which stage of the condition. A 2017 review found that both methods may have advantages for treating certain symptoms (37). Surgery leads to symptom relief in most people with mild or moderate endometriosis, but is not always effective and recurrence (and the need for further surgical procedures) is common over time (37-41). Surgery also carries its own risks which need to be weighed against potential benefits.

A hysterectomy (removal of the uterus, fallopian tubes, and sometimes the ovaries) might be considered as a “last stop” treatment option in severe cases after other treatment methods have been exhausted. A hysterectomy does not effectively treat endometriosis in all cases, but has lower retreatment rates than other surgeries, especially when ovaries are removed (42). The European Society of Human Reproduction and Embryology (ESHRE) guidelines state that removal of the ovaries should be considered a “radical” treatment option, as it results in surgical menopause in women of reproductive age (33).

Lifestyle changes

Some people consider alternative treatments for their symptoms. These include physical exercise, diet changes, and acupuncture (43-45). Unfortunately, there is still little research and a lack of evidence for the effectiveness of many of these approaches. Only one study of 24 met the criteria for inclusion in a review on acupuncture for pain in endometriosis, and did find an improvement in painful menstruation (especially when severe), but more high quality research is needed (45).

What to track in Clue app

Essential to track

  • Bleeding patterns (including spotting)

  • Pain

Helpful to track

  • Menstrual heaviness

  • Energy

  • Stool

  • Gastrointestinal symptoms, such as bloating and diarrhea

  • Contraception use

You can learn more by checking out the work and initiatives of Clue research collaborator Noemie Elhadad, and colleagues, from Columbia University: Citizen Endo is a research project led by the Department of Biomedical Informatics in partnership with patients to better understand endometriosis. They've published on endometriosis and self-tracking and collected experience stories of women with the disease.

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