Not Just a Pelvic Problem: Endometriosis is linked to migraines, asthma, and more

The pain from endometriosis, which affects an estimated one in 10 Americans born female, can be terrible. Some people are unable to work or go to school. Yet many physicians don’t recognize the symptoms. On average, it takes sufferers seven to nine years to get a diagnosis. That startling statistic, along with the general lack of familiarity with endometriosis, is a powerful example of the gap in knowledge about women’s and men’s health. There has been limited funding and investigation into what causes endometriosis or who is at highest risk. That is finally changing, in part because the understanding of endometriosis is changing. It is not purely a gynecological condition. “In the past three to five years there’s been a complete reframing of this disorder as a neuroinflammatory whole-body condition,” says reproductive biologist Philippa Saunders of the University of Edinburgh. “It isn’t just about a little bit of tissue stuck in the wrong place. Your whole body has reacted.” Endometriosis, which involves tissue from the uterus, begins with a process known as retrograde menstruation, in which menstrual blood flows back up the fallopian tubes and into the pelvis. The blood carries bits of endometrial tissue, which lines the uterus. Sometimes, instead of being cleaned up by the immune system, this tissue adheres to the ovaries or pelvic lining, then grows and creates its own blood supply. The lesions can cause infertility as well as debilitating pain. “We’re not talking a little bit of pain here,” Saunders says. “[People] can’t function.” And unlike menstrual cramping that occurs during a period, pain from endometriosis can flare at any time. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. The medical profession’s habit of restricting health issues to narrow silos—traditionally, only gynecologists saw endometriosis patients—hasn’t helped. “We chop up human health into specialties and systems, but we know now that [those systems are] much more interconnected than we had presumed,” says Stacey Missmer, a reproductive biologist at Michigan State University. Endometriosis creates symptoms and consequences that affect many other parts of the body, she points out. For example, adolescents and young women with endometriosis are five times more likely to be diagnosed with irritable bowel syndrome than women with no endometriosis. Cardiovascular events are rare in all women younger than 60, but in those with endometriosis, the relative risk of high blood pressure, stroke, angina or heart attack increases by 20 to 80 percent, depending on the study and condition. Patients are at twice the risk of rheumatoid arthritis, and asthma, lupus and osteoarthritis have higher prevalence among people with endometriosis. These people are also more likely to suffer from overlapping conditions such as migraines, low back pain and fibromyalgia, a chronic pain condition. Scientists cannot yet say for sure why these conditions are so often seen together. “We think one of the key pathways is chronic inflammation,” Missmer says. It could be, for instance, that affected people have inflammatory responses to certain triggers that some diseases share. Researchers do know that about half the risk of endometriosis results from genetic factors. Although early studies failed to find a common high-risk gene for the condition—one akin to the BRCA gene for breast cancer—more recent large-scale work has implicated genetic variations across the genome. A 2023 study in Nature Genetics of about 60,000 people with endometriosis and over 700,000 without the condition found more than 40 places in the genome that harbor changes associated with a higher risk of the disease. “That really led to a jump in our understanding,” says genetic epidemiologist Krina Zondervan of the University of Oxford. That jump, in the same study, allowed researchers to highlight shared biology in some of the diseases that often co occur with endometriosis. For instance, they found a link in the genetics underlying endometriosis and other types of pain, such as migraines. Such pain conditions trigger a biological process called central sensitization, which occurs when chronic pain changes the way the central nervous system reacts to pain stimuli, and many of the genes involved are associated with pain perception or maintenance. They also found links to inflammatory conditions such as asthma. What may help with diagnosis and treatment is the recent recognition that endometriosis is not a single disease. It’s a condition with three subtypes. Ovarian endometriosis, which results in lesions on the ovaries, is the most heritable. Deep endometriosis infiltrates farther into the pelvis and produces very hard nodules. In peritoneal or superficial endometriosis, smaller lesions scatter more diffusely along the pelvic lining. As in breast cancer, the subtypes most likely have different risk factors. Until recently, the only way to diagnose endometriosis was laparoscopic surgery. But now less invasive methods are being used. Ultrasound imaging can spot ovarian endometriosis, for instance, and an MRI scan can reveal lesions of the deep form. Unfortunately, imaging doesn’t yet work well for peritoneal endometriosis, the most common type. Also, patients need to be referred for such imaging, and not everyone is because of misdiagnosis and inequities in health-care access. For treatment, surgical removal of lesions works for some but not all patients. Identifying the accompanying conditions may determine who won’t be helped. Those suffering from widespread pain beyond the pelvis may not benefit from surgery. “There’s not something to cut out,” Missmer says. Clinical trials are underway in the U.K. to study outcomes with and without surgery. Right now anyone with a diagnosis of endometriosis or with worrying symptoms should discuss it not just with a gynecologist but with their primary doctor, too. This is not a one-body-part problem.