Endometriosis is a chronic, often painful condition that affects an estimated 1 in 10 people with a uterus during their reproductive years, roughly 190 million people worldwide. Despite how common it is, endometriosis remains widely misunderstood, underdiagnosed, and under-researched. On average, it takes several years from the first onset of symptoms to receive an accurate diagnosis, with many people told for years that their pain is normal, psychological, or simply “bad periods.”
This article offers a comprehensive look at endometriosis: what it is, how it develops, its symptoms, how it’s diagnosed, the range of available treatments, and what it means to live with the condition day to day.
What Is Endometriosis?
Endometriosis occurs when tissue similar to the lining of the uterus, called the endometrium, grows outside the uterus. This tissue is most commonly found on and around the pelvic organs: the ovaries, fallopian tubes, the outer surface of the uterus, the ligaments supporting the uterus, the bladder, and the bowel. Less commonly, it can appear on the diaphragm, in the lungs, or in surgical scars, and in rare cases even further afield in the body.
Like the tissue lining the uterus, these misplaced growths (called lesions or implants) contain hormone receptors and respond to the hormonal fluctuations of the menstrual cycle. Each month, they thicken, break down, and bleed in a process similar to menstruation. But because this tissue is not inside the uterus, the blood has no natural way to exit the body. It becomes trapped in the surrounding tissue, triggering inflammation, irritation, and, over time, scarring.
This scarring can lead to the formation of adhesions, which are bands of fibrous tissue that cause organs and tissues to stick together that normally would not. In advanced cases, adhesions can distort pelvic anatomy, bind organs to one another, and contribute to chronic pain independent of the menstrual cycle.
Endometriosis is classified into different types based on where and how the tissue grows:
- Superficial peritoneal endometriosis: lesions on the thin membrane lining the pelvic cavity (the peritoneum). This is the most common form.
- Endometrioma (ovarian endometriosis): cysts that form on the ovaries, sometimes called “chocolate cysts” because they contain thick, dark, old blood.
- Deep infiltrating endometriosis (DIE): tissue that grows more than 5mm beneath the peritoneal surface, often affecting the bowel, bladder, or the area between the vagina and rectum. This form tends to cause more severe symptoms and can be more complex to treat surgically.
Doctors also use a staging system (Stage I through IV) to describe the extent of disease found during surgery, based on the location, depth, and number of lesions, as well as the presence of adhesions. It’s important to note that stage does not reliably predict the severity of symptoms. Someone with Stage I disease can experience debilitating pain, while someone with Stage IV disease may have relatively few symptoms.
How Common Is It, and Who Does It Affect?
Endometriosis can affect anyone who menstruates, typically emerging any time after the first period and persisting until menopause, though symptoms can sometimes continue afterward, particularly for those on hormone replacement therapy. It has been documented in people as young as their early teens.
While endometriosis is sometimes framed narrowly as a “women’s health issue,” it’s worth noting that it affects anyone with a uterus and functioning ovaries, including some transgender men and nonbinary people, who often face additional barriers to diagnosis and care due to a lack of clinician familiarity with their needs.
Common Symptoms
Symptoms of endometriosis vary enormously from person to person, both in type and severity, and, as noted above, severity doesn’t necessarily correlate with how much tissue has grown or where. The most frequently reported symptoms include:
- Pelvic pain, which may be constant or may flare around menstruation
- Dysmenorrhea (painful periods) that is often more intense than typical menstrual cramps and may begin days before bleeding starts
- Dyspareunia, or pain during or after sexual intercourse, particularly with deep penetration
- Painful bowel movements or urination, especially during menstruation
- Heavy menstrual bleeding, prolonged periods, or bleeding and spotting between periods
- Chronic fatigue, which can be significant and is sometimes overlooked as a symptom
- Gastrointestinal symptoms, including bloating (sometimes called “endo belly”), constipation, diarrhea, or nausea, especially around the menstrual cycle
- Lower back and leg pain, sometimes radiating from the pelvis
- Difficulty conceiving: endometriosis is found in a significant proportion of people evaluated for infertility
A subset of people with endometriosis experience few or no symptoms at all, and the condition is discovered incidentally, for instance during a fertility workup or unrelated abdominal surgery. This variability is part of why the condition is so often missed or misattributed to other causes.
What Causes Endometriosis?
The precise cause of endometriosis is not yet fully understood, and researchers increasingly believe it results from a combination of factors rather than a single mechanism. Leading theories include:
Retrograde menstruation. This long-standing theory proposes that during menstruation, some blood flows backward through the fallopian tubes into the pelvic cavity instead of leaving the body, allowing endometrial cells to implant and grow outside the uterus. However, retrograde menstruation is common and occurs in most menstruating people, most of whom never develop endometriosis, suggesting other factors must also be at play.
Coelomic metaplasia. This theory suggests that certain cells outside the uterus can transform into endometrial-like cells under the right hormonal or inflammatory conditions.
Immune system dysfunction. Normally, the immune system would be expected to identify and clear misplaced endometrial-like cells. Some research suggests that immune dysregulation may allow these cells to survive and grow instead.
Genetic and epigenetic factors. Endometriosis tends to run in families. Having a first-degree relative with the condition significantly increases risk, and researchers have identified several genetic variants associated with higher susceptibility.
Lymphatic or vascular spread. Endometrial cells may travel to distant sites in the body via the lymphatic system or bloodstream, which could help explain rare cases of endometriosis found outside the pelvis, such as in the lungs.
Surgical scar implantation. In some cases, endometrial cells appear to become implanted in a surgical incision, such as after a cesarean section, leading to localized endometriosis at the scar site.
It’s likely that different combinations of these mechanisms are relevant for different individuals, which is part of why endometriosis presents so differently from person to person and why a single unifying cause has been difficult to establish.
Diagnosis
Diagnosing endometriosis is often a lengthy and frustrating process. Because its symptoms overlap substantially with other conditions, including irritable bowel syndrome, pelvic inflammatory disease, ovarian cysts, interstitial cystitis, and other causes of chronic pelvic pain, it is frequently misdiagnosed or dismissed, particularly in the early stages of investigation.
The diagnostic process typically involves several steps:
Clinical history. A detailed conversation about symptoms, their timing and severity, menstrual history, and family history is often the starting point. Because pain is subjective and can’t be measured directly, clinicians rely heavily on a thorough history.
Pelvic examination. A physical exam can sometimes detect tenderness, masses, or nodules suggestive of endometriosis, though a normal exam does not rule it out.
Imaging. Transvaginal ultrasound is commonly used and can identify larger endometriomas (ovarian cysts), though it often misses smaller superficial lesions. MRI can provide more detailed imaging and is particularly useful for detecting deep infiltrating endometriosis, especially when it affects the bowel or bladder.
Laparoscopy. For many years, laparoscopic surgery, a minimally invasive procedure in which a camera is inserted through a small incision to directly visualize the pelvic organs, was considered the only definitive way to diagnose endometriosis, allowing for direct visualization and biopsy of suspected lesions.
More recently, clinical guidelines in many countries have shifted toward a “clinical diagnosis” model, where treatment can begin based on symptoms, history, and imaging findings alone, without requiring surgical confirmation first. This shift reflects growing recognition that delaying treatment until a surgical diagnosis can prolong suffering unnecessarily, and that laparoscopy carries its own risks and costs. Surgery is still often used when diagnosis remains unclear, when first-line treatments haven’t helped, or when there’s a specific surgical indication such as a large endometrioma.
Treatment Options
There is currently no cure for endometriosis, but a range of treatments can help manage symptoms, slow disease progression, and improve quality of life. Treatment is typically individualized based on symptom severity, whether fertility is a current priority, and personal preference.
Pain Management
For milder symptoms, over-the-counter pain relievers such as NSAIDs (ibuprofen, naproxen) are often tried first, as they can help reduce both pain and the inflammation associated with lesion activity. For more severe pain, prescription pain management strategies may be considered under medical supervision.
Hormonal Therapy
Because endometrial-like tissue responds to hormonal signals, therapies that regulate, suppress, or eliminate those signals are a mainstay of treatment:
- Combined hormonal birth control (pills, patches, or vaginal rings) can reduce or eliminate periods and slow the growth of endometrial tissue.
- Progestin-only therapies, including certain pills, injections, implants, and hormonal IUDs, can thin the uterine lining and reduce lesion activity.
- GnRH agonists and antagonists work by inducing a temporary, medically controlled menopause-like state, significantly lowering estrogen levels to shrink lesions and reduce pain. Because of the side effects associated with low estrogen (such as bone density loss), these are often used for limited periods, sometimes alongside “add-back” therapy to offset side effects.
- Aromatase inhibitors are sometimes used in more complex or treatment-resistant cases to reduce estrogen production throughout the body.
Surgery
Laparoscopic surgery can be used both to diagnose and to treat endometriosis by removing or destroying visible lesions and adhesions, either through excision (cutting out the tissue) or ablation (burning or vaporizing it). Excision is generally considered more thorough, particularly for deep infiltrating disease, as it removes the full lesion rather than just its surface.
Surgery can meaningfully reduce pain and, for some, improve fertility outcomes, though symptoms can recur over time as new lesions develop. In severe, treatment-resistant cases, a hysterectomy (removal of the uterus), sometimes along with the ovaries, may be considered. This is not a guaranteed cure, however, since endometrial-like tissue located elsewhere in the body can remain and continue to cause symptoms.
Fertility Treatment
Endometriosis is one of the leading causes of infertility, though many people with the condition do conceive, some without any intervention. For those having difficulty, options range from ovulation-stimulating medications to intrauterine insemination (IUI) to in vitro fertilization (IVF), with the right approach depending on age, disease severity, and other fertility factors. In some cases, surgical removal of lesions or endometriomas before fertility treatment can improve outcomes.
Complementary and Supportive Approaches
Many people find additional relief through approaches used alongside, not in place of, medical treatment:
- Pelvic floor physical therapy, which can address muscle tension and pain patterns that often develop secondary to chronic pelvic pain
- Dietary changes, such as reducing inflammatory foods, though evidence for specific “endo diets” is still limited
- Acupuncture, which some studies suggest may help with pain management
- Stress-reduction techniques, such as mindfulness or therapy, which can help with the significant mental load of living with chronic pain
- Heat therapy and gentle exercise, which some people find helpful for symptom flares
Living with Endometriosis
The impact of endometriosis often extends well beyond physical pain. Chronic pain can affect sleep, concentration, work and school attendance, and relationships. The long road to diagnosis, often marked by having pain dismissed or minimized, can take a toll on mental health, and rates of anxiety and depression are notably higher among people with endometriosis than the general population.
Building a care team that takes symptoms seriously can make a substantial difference. This might include a gynecologist familiar with endometriosis (ideally one with specific expertise in excision surgery, if surgery is being considered), a pain management specialist, a pelvic floor physical therapist, and mental health support. Peer support groups and communities, online or in person, can also help address the isolation that often comes with a chronic, invisible illness.
Workplace and school accommodations, such as flexible scheduling around symptom flares, can also be an important part of managing the condition long-term, and some people find it helpful to track their symptoms over time to identify patterns and better communicate with their healthcare providers.
Endometriosis and Research: What’s Changing
Endometriosis has historically been underfunded relative to its prevalence and impact, a gap that researchers and advocates attribute partly to the long-standing normalization of menstrual pain and partly to broader disparities in funding for conditions that predominantly affect women. In recent years, that has begun to shift, with growing investment in research into the condition’s underlying biology, non-invasive diagnostic tools (such as blood-based biomarkers that could reduce reliance on surgery for diagnosis), and new drug therapies that target inflammation and lesion growth more precisely.
Advocacy movements have also helped raise public awareness, encouraging more people to seek evaluation for symptoms they may have previously accepted as normal, and pushing for improved medical education so that clinicians are better equipped to recognize and diagnose the condition earlier.
When to See a Doctor
Anyone experiencing persistent pelvic pain, periods that are significantly more painful than what over-the-counter medication can manage, pain during sex that interferes with daily life, or unexplained difficulty conceiving should consider speaking with a healthcare provider. Symptoms shouldn’t be dismissed as “just bad periods.” Early evaluation can lead to more effective symptom management and, for those who want to conceive, better fertility outcomes. If a first provider doesn’t take symptoms seriously, seeking a second opinion, ideally from a clinician with specific experience in endometriosis, is a reasonable and often nece
Conclusion
Endometriosis is a complex, common, and frequently misunderstood condition that can have a profound impact on quality of life. While there is no cure, a growing understanding of the disease, paired with a widening range of treatment options, means that most people with endometriosis can find an approach that meaningfully reduces their symptoms. Continued research, greater awareness, and better-informed healthcare providers all play a role in closing the long gap between the onset of symptoms and effective care.
Take Action Today
If any of this sounds familiar, don’t wait years for answers the way so many others have. Start a symptom journal today, noting pain levels, timing, and triggers, so you walk into your next appointment prepared. Book a visit with a gynecologist, and if your concerns are brushed aside, seek a second opinion from a provider with specific experience in endometriosis. Reach out to a support community so you’re not navigating this alone. Your pain is real, it’s valid, and effective care exists. The first step is simply refusing to accept “normal” as an answer.
Book a test at Biopassion Diagnostics
Contact Us +254704150555