Endometriosis: The Disease Affecting 1 in 10 Women That Most People Don’t Learn About Until They’re Already Suffering
If one in ten men had a disease that caused this level of pain, inflammation, and disruption to daily life, we would likely learn about it in middle school health class. Instead, most people don’t learn what endometriosis is until they, or someone they love, are already suffering from it.
Endometriosis affects approximately 1 in 10 women and people assigned female at birth worldwide, which translates to nearly 190 million individuals globally. Despite being one of the most common chronic gynecological diseases, it remains widely misunderstood, underdiagnosed, and historically underfunded (Zondervan et al., 2018; PMID: 29574452).
For many people, the journey to understanding the disease begins the same way it did for me — with a body that starts sending signals that something deeper is wrong.
When Your Body Starts Sending Signals Something Is Wrong
For years my body was dropping hints that something deeper was going on.
The symptoms didn’t appear as one obvious problem. Instead, they showed up as a constellation of issues that seemed unrelated at first: severe bloating, pelvic pain, gastrointestinal symptoms, fatigue that didn’t match my lifestyle, hormonal instability, and systemic inflammation that felt like it came out of nowhere.
Individually, each symptom could be explained away. Maybe it was stress. Maybe it was diet. Maybe it was IBS. Maybe it was simply “bad periods.” None of the symptoms clearly pointed to one diagnosis, and that is one of the reasons endometriosis is so often missed.
For millions of people, these seemingly random symptoms are actually connected. It just takes years for anyone to realize it.
What Is Endometriosis?
Endometriosis is a chronic inflammatory disease defined by the presence of tissue similar to the endometrium (the lining of the uterus) growing outside the uterine cavity.
These lesions are most commonly found on pelvic structures including the ovaries, fallopian tubes, pelvic peritoneum, bladder, and bowel. However, endometriosis has also been identified in more distant locations including the diaphragm, abdominal wall, and peripheral nerves (Giudice, 2010; PMID: 20478545).
Because of this, endometriosis is not simply a reproductive condition. It is increasingly understood as a systemic inflammatory disease involving hormonal, immune, and neurological pathways (Burney & Giudice, 2012; PMID: 22772044).
What Causes Endometriosis?
One of the most common questions people ask is “what actually causes endometriosis?”
The honest answer is that scientists still don’t fully know. Endometriosis is considered a complex, multifactorial disease, meaning it likely develops from a combination of genetic, hormonal, immune, and environmental factors rather than a single cause.
One long-standing theory is retrograde menstruation, where menstrual blood flows backward through the fallopian tubes into the pelvic cavity. However, retrograde menstruation occurs in many people who never develop endometriosis, which suggests it cannot be the sole explanation.
Researchers now believe the disease may involve a combination of mechanisms, including immune dysfunction that allows endometrial-like cells to implant and survive outside the uterus, chronic inflammatory signaling that promotes lesion growth, and hormonal factors that stimulate the tissue to proliferate. There is also strong evidence for a genetic component, as individuals with a close relative who has endometriosis are significantly more likely to develop the condition themselves.
Emerging research is also exploring the role of environmental exposures, alterations in the microbiome, and stem cell activity in the development of endometriosis. The reality is that endometriosis likely develops through a complex interaction of biological systems, which is one reason the disease can be so difficult to diagnose and treat.
Why Endometriosis Causes So Much Pain
Endometriosis lesions respond to hormonal signals during the menstrual cycle, particularly estrogen, which promotes growth and inflammation within the lesions.
As hormone levels fluctuate, endometriotic tissue can proliferate, swell, bleed, and stimulate inflammatory signaling pathways.
Unlike the uterine lining, however, this tissue has no natural outlet to leave the body, which leads to a persistent inflammatory environment within the pelvic cavity.
Over time, chronic inflammation can lead to fibrosis, scar tissue formation, and adhesions that tether organs together. In advanced cases, surgeons may find ovaries adhered to the bowel or the uterus fused to surrounding structures by fibrotic tissue (Bulun, 2009; PMID: 19196841).
Inflammation and nerve sensitization also contribute to the chronic pain experienced by many patients with endometriosis (Stratton & Berkley, 2011; PMID: 21497367).
Endometriosis Has Some Cancer-Like Biological Behaviors
Although endometriosis is classified as a benign condition, it shares several biological features with malignant disease processes.
Endometriosis lesions can invade surrounding tissues, recruit new blood vessels through angiogenesis, evade immune surveillance, and proliferate in response to hormonal signaling (Vigano et al., 2018; PMID: 29374627). These characteristics help explain how lesions can establish themselves in new locations and persist over time.
However, unlike cancer, endometriosis does not metastasize through the bloodstream or lymphatic system in the same way malignant tumors do.
Despite this distinction, the invasive nature of the disease contributes to the structural damage, chronic inflammation, and severe pain that many patients experience.
Common Symptoms of Endometriosis
The clinical presentation of endometriosis varies widely between individuals.
While severe menstrual pain (dysmenorrhea) is often the most recognized symptom, many people experience a broader range of manifestations including chronic pelvic pain, painful intercourse, pain during bowel movements or urination, severe bloating, fatigue, and gastrointestinal disturbances.
Because of the overlap with other conditions, endometriosis is frequently misdiagnosed as irritable bowel syndrome or other gastrointestinal disorders (Zondervan et al., 2020; PMID: 32188952).
Endometriosis is also strongly associated with infertility, affecting an estimated 30–50% of individuals experiencing difficulty conceiving (Practice Committee of the ASRM, 2012; PMID: 23182321).
What Is “Endo Belly”?
Another symptom that many people with endometriosis experience, but that often goes unrecognized, is something commonly referred to as “endo belly.”
Endo belly describes the severe abdominal bloating and distention that can occur with endometriosis. For some individuals, the abdomen can become dramatically swollen, sometimes expanding several inches in circumference over the course of a day.
This bloating is not simply cosmetic or digestive discomfort. It is believed to result from a combination of inflammatory processes, hormonal fluctuations, gastrointestinal involvement, and altered nervous system signaling.
Endometriosis is strongly associated with gastrointestinal symptoms such as constipation, diarrhea, nausea, and abdominal pain. In some cases, lesions directly involve the bowel. In others, inflammation within the pelvic cavity affects surrounding organs and nerve pathways, contributing to digestive disturbances and visceral hypersensitivity.
For many people, endo belly is one of the most frustrating aspects of the disease because it can appear suddenly and significantly impact daily life, clothing comfort, body image, and physical activity.
Can Endometriosis Be Cured?
Currently, there is no known cure for endometriosis.
However, there are treatments that can help manage symptoms and improve quality of life. Treatment approaches often include hormonal therapies designed to suppress the hormonal stimulation of endometriosis lesions, pain management strategies, and surgical interventions to remove endometriotic tissue.
One of the most effective surgical approaches is excision surgery, where a specialist carefully removes endometriosis lesions from affected tissues. For some individuals, excision surgery can significantly reduce symptoms and improve fertility outcomes.
However, even with surgery, endometriosis can sometimes recur, which is why ongoing research is so critical.
Improving treatment outcomes requires better diagnostic tools, earlier detection, and a deeper understanding of the biological mechanisms driving the disease.
Why Endometriosis Takes 7–10 Years to Diagnose
Despite affecting roughly one in ten women, the average diagnostic delay for endometriosis is between seven and ten years (Nnoaham et al., 2011; PMID: 22194015).
Nearly a decade of symptoms. Nearly a decade of wondering why your body feels like it is working against you. Nearly a decade of hearing phrases like “bad periods are normal” or “maybe it’s just stress.”
Several factors contribute to this delay. One major issue is the lack of reliable non-invasive diagnostic tools.
Currently, there is no widely accepted blood test capable of diagnosing endometriosis, and imaging modalities such as ultrasound or MRI frequently fail to detect superficial lesions.
The gold standard diagnosis remains laparoscopic surgery, during which surgeons visually identify and often biopsy lesions to confirm the disease.
For many patients, this requirement for surgical diagnosis contributes to years of delayed answers. That was true for me as well. Eventually, my own journey led to surgery.
Endometriosis Is a Whole-Body Disease
One of the most persistent misconceptions about endometriosis is that it is purely a gynecological condition.
Research increasingly shows that the disease involves complex interactions between hormonal signaling, immune dysregulation, inflammatory pathways, and nervous system sensitization.
These systemic processes help explain why people with endometriosis frequently experience fatigue, digestive disturbances, and chronic pain that extends beyond the pelvis (Burney & Giudice, 2012; PMID: 22772044).
Understanding endometriosis as a systemic inflammatory disease rather than solely a reproductive disorder is essential for improving diagnostic and treatment approaches.
The Endometriosis Research Funding Gap
Despite affecting nearly 200 million people globally, endometriosis research has historically received relatively little funding.
For many years, the U.S. National Institutes of Health allocated under $30 million annually toward endometriosis research which is a small fraction of the agency’s overall biomedical research budget.
Limited funding has slowed progress toward better diagnostic tools, improved treatments, and a deeper understanding of the disease’s underlying mechanisms.
Increasing investment in endometriosis research is critical for reducing diagnostic delays and improving outcomes for millions of patients.
Why Endometriosis Awareness Matters
Right now, someone reading this article is living with endometriosis and doesn’t know it yet. Their symptoms may have been dismissed, normalized, or attributed to something else entirely. For many people, it takes years before someone finally connects the dots.
If something about your body doesn’t feel right, keep advocating for yourself. Your pain & symptoms deserve to be taken seriously.
References
Zondervan KT et al. Endometriosis. Nat Rev Dis Primers. 2018. PMID: 29574452
Giudice LC. Clinical practice: Endometriosis. N Engl J Med. 2010. PMID: 20478545
Burney RO & Giudice LC. Pathogenesis and pathophysiology of endometriosis. Fertil Steril. 2012. PMID: 22772044
Bulun SE. Endometriosis. N Engl J Med. 2009. PMID: 19196841
Stratton P & Berkley KJ. Chronic pelvic pain and endometriosis. Nat Rev Endocrinol. 2011. PMID: 21497367
Vigano P et al. Endometriosis: epidemiology and etiological factors. Best Pract Res Clin Obstet Gynaecol. 2018. PMID: 29374627
Nnoaham KE et al. Impact of endometriosis on quality of life. Hum Reprod. 2011. PMID: 22194015
Practice Committee ASRM. Endometriosis and infertility. Fertil Steril. 2012. PMID: 23182321
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