You can absolutely have PCOS and endometriosis at the same time, and the overlap is more common than many clinicians once assumed. In one clinical study, roughly one in four women with endometriosis also met criteria for PCOS. The two conditions were long treated as near-opposites because their hormonal profiles trend in different directions, which led to a persistent belief that having one essentially ruled out the other. That belief has not held up well under scrutiny.
How Often the Two Conditions Overlap
Pinning down exact numbers depends on who you study and how you look. In a large population-based cohort, about 2% of women had both endometriosis and PCOS documented in their medical records. In a smaller operative cohort of women who had undergone surgery, the co-occurrence rate was higher at around 5%.1PubMed Central. Examining the co-occurrence of endometriosis and polycystic ovarian syndrome Those numbers may look modest, but they likely undercount the real overlap. Endometriosis can only be confirmed definitively through surgery, and PCOS diagnosis itself is inconsistent. Many people with both conditions have one diagnosed and the other missed for years.
A cross-sectional study focusing on women already diagnosed with endometriosis found that about a quarter of them also had PCOS. Women with both conditions had significantly higher rates of infertility and reported worse symptoms than women with endometriosis alone. Having both roughly doubled the odds of infertility compared to endometriosis on its own.2PubMed Central. Epidemiological study and clinical consequences of endometriosis and PCOS co-occurrence in a clinical population of women The takeaway is that these conditions co-occur often enough that assuming one rules out the other can delay the right diagnosis and treatment.
Why Doctors Once Thought They Were Mutually Exclusive
For decades, a popular framework in reproductive medicine positioned PCOS and endometriosis as hormonal opposites. The logic went like this: PCOS is associated with higher-than-typical testosterone and other androgens, irregular or absent ovulation, and metabolic features like insulin resistance. Endometriosis, meanwhile, is driven by estrogen and involves tissue resembling the uterine lining growing outside the uterus, typically in the pelvis. One hypothesis framed the two conditions as “diametric disorders,” proposing that they stem from opposite ends of a hormonal spectrum shaped during development, with PCOS linked to high prenatal testosterone exposure and endometriosis linked to low prenatal testosterone.3Evolutionary Applications. Endometriosis and polycystic ovary syndrome are diametric disorders
That framework is intellectually tidy, but biology rarely cooperates with tidy frameworks. The prediction that these two conditions should almost never appear in the same person has been contradicted by the clinical data described above. The diametric model captures real hormonal differences between the two conditions in their “textbook” forms, but it underestimates how much individual hormonal profiles vary and how many other mechanisms feed into each disease. The idea that they’re opposites still circulates widely, and it can create a blind spot: a woman with a PCOS diagnosis who reports severe pelvic pain may have her symptoms attributed to something else rather than getting evaluated for endometriosis.
What Ultrasound Imaging Reveals
One piece of evidence challenging the opposites narrative comes from imaging. A study using transvaginal ultrasound looked specifically at whether polycystic ovarian morphology (the appearance of many small follicles on the ovary, a hallmark of PCOS) and endometriosis coexist in the same patients. Among 165 patients, about 37% showed polycystic ovarian morphology and about 62% had endometriosis. Roughly a third of those with confirmed endometriosis also had that characteristic polycystic appearance on their ovaries.4Ultrasound in Obstetrics & Gynecology. Challenging prior assumptions: coexistence of polycystic ovarian morphology and endometriosis on transvaginal ultrasound In the overall group, having polycystic-looking ovaries did not make endometriosis less likely, though deep endometriosis was less frequent in people with that ovarian pattern. The researchers framed their findings as directly challenging prior assumptions about the two conditions being incompatible.
This matters practically. If a clinician sees polycystic ovaries on an ultrasound, the reflex may be to stop looking. But those same ovaries can sit alongside endometriotic cysts or superficial endometrial implants. An ultrasound that confirms one condition should not automatically close the door on investigating the other, particularly when symptoms don’t fully fit a single diagnosis.
Shared Biological Threads
Despite their hormonal differences, PCOS and endometriosis share more biology than their surface-level profiles suggest. The most striking overlap is chronic low-grade inflammation. In both conditions, pro-inflammatory signaling molecules tend to be elevated in the fluid surrounding developing eggs inside the ovary. This inflamed environment can trigger oxidative stress and tissue damage, which compromises egg quality and follicle development.5Frontiers in Endocrinology. Chronic low-grade inflammation and ovarian dysfunction in women with polycystic ovarian syndrome, endometriosis, and aging Research on immune cells in these patients supports that picture: macrophages and their associated inflammatory signaling appear to play a role in driving ovarian inflammation in both PCOS and endometriosis.6Human Reproduction. The role of macrophages in systemic and local ovarian inflammation in infertile women with endometriosis and PCOS So even though the hormonal triggers differ, both conditions converge on the same downstream problem: an ovarian environment that is less hospitable to healthy egg development.
Genetics adds another layer of shared ground. A study using large-scale genetic data found a positive genetic association between the two conditions and identified 12 spots in the genome that influence risk for both.7PubMed Central. Dissecting the shared genetic architecture between endometriosis and polycystic ovary syndrome Separate work has pointed to specific gene variants that affect disease risk for both conditions by altering how genes are expressed in reproductive tissue.8Scientific Reports. Genetic regulation of disease risk and endometrial gene expression highlights potential target genes for endometriosis and polycystic ovarian syndrome None of this means PCOS causes endometriosis or the reverse. It means the genetic wiring that predisposes someone to one condition doesn’t protect them from the other, and in some cases actively raises their risk for both.
An emerging line of research also implicates the gut microbiome. A review has proposed what researchers call the “Gut-Reproduction-Oral-Immune Axis,” arguing that disrupted gut bacteria may be a shared upstream driver for both conditions. Despite different core features, PCOS and endometriosis show similar patterns of microbial imbalance that may fuel disease through inflammation and immune dysregulation.9PubMed. The Gut-Reproduction-Oral-Immune Axis: Microbial Dysbiosis as a Shared Driver in Polycystic Ovary Syndrome and Endometriosis This is still early-stage work, but it reinforces the picture of conditions that are far less separate than the older hormonal-opposites framework suggested.
Why Getting Both Conditions Diagnosed Is So Difficult
Diagnostic delays are already a well-known problem for each condition individually. People with endometriosis wait an average of seven to ten years from the onset of symptoms to a confirmed diagnosis. PCOS diagnosis varies depending on which clinical criteria a doctor uses, and many cases are caught incidentally during fertility workups rather than because someone connected the dots between irregular periods, acne, and metabolic symptoms.
When both conditions are present, the challenge compounds. Symptoms can mimic each other or get attributed to a single diagnosis. Pelvic pain, for instance, is the hallmark complaint of endometriosis but also occurs with large ovarian cysts in PCOS. Irregular periods are a core criterion for PCOS but also occur in people with endometriosis. On top of that, conditions like irritable bowel syndrome, inflammatory bowel disease, interstitial cystitis, and fibromyalgia share overlapping pain symptoms with endometriosis and can lead to false or delayed diagnoses.10PubMed Central. Burden of Endometriosis: Infertility, Comorbidities, and Healthcare Resource Utilization Add a PCOS diagnosis into the mix, and a clinician may attribute chronic pain to ovarian cysts rather than pursuing the surgical evaluation needed to find endometrial implants.
One useful indicator that both conditions may be at play: if your treatment for one condition isn’t resolving all your symptoms. Someone on hormonal management for PCOS who still has worsening pelvic pain around their period, pain during sex, or bowel symptoms that cycle with their menstrual pattern should push for further investigation. Similarly, someone treated for endometriosis who continues to have very irregular cycles, signs of androgen excess like persistent acne or unusual hair growth, or metabolic issues like insulin resistance may benefit from a PCOS evaluation.
What Happens to Fertility
Both PCOS and endometriosis independently affect the ability to conceive, and having both makes things harder. The co-occurrence study cited earlier found that women with both conditions had roughly twice the odds of infertility compared to those with endometriosis alone.2PubMed Central. Epidemiological study and clinical consequences of endometriosis and PCOS co-occurrence in a clinical population of women The mechanisms are somewhat different for each condition. PCOS primarily impairs fertility through irregular or absent ovulation: if you don’t release an egg predictably, conception becomes a matter of chance. Endometriosis impairs fertility through inflammation, adhesions, and structural damage to the fallopian tubes and ovarian tissue.
When both are present, you can end up dealing with both problems simultaneously. Ovulation may be unpredictable, and even when it does occur, the inflammatory environment may compromise egg quality or block the egg’s path. Research on egg quality in IVF patients has found that oocytes from women with endometriosis and those with PCOS show different patterns of cellular stress. In one study, oocytes from endometriosis patients had visible spindle structures (a sign of maturity) more often than those from PCOS patients, but pregnancy rates after IVF were actually lower in the endometriosis group.11PubMed Central. Assessment of oocyte quality in polycystic ovarian syndrome and endometriosis by spindle imaging and reactive oxygen species levels in follicular fluid and its relationship with IVF-ET outcome That hints at how tricky fertility management gets when both conditions are involved, since the two diseases undermine egg development and implantation through different pathways.
An encouraging finding: among women with PCOS who were found to also have endometriosis, the endometriosis was predominantly mild. About three-quarters had stage I or II disease, the earliest and least structurally damaging forms.12Journal of Endometriosis and Pelvic Pain Disorders. Coexistence of Polycystic Ovary Syndrome and Endometriosis in Women with Infertility That doesn’t mean the impact on fertility is trivial, since even minimal endometriosis can create enough inflammation to impair conception, but it does suggest that the endometriosis in co-occurrence cases may respond better to treatment than advanced-stage disease.
Pregnancy Risks When Both Conditions Are Present
Getting pregnant is one challenge; staying pregnant safely is another. A population-level study examined pregnancy, delivery, and newborn outcomes in women who had both PCOS and endometriosis and compared them to women with neither condition. The dual-diagnosis group had significantly higher rates of several serious complications. Placental abruption, where the placenta separates from the uterine wall before delivery, was about three times more likely. Cesarean delivery rates were also elevated, with roughly 75% higher odds. Blood clot complications, including deep vein thrombosis and other venous clotting events, were dramatically more frequent in the dual-diagnosis group.13PubMed. Pregnancy, delivery, and neonatal outcomes among women with PCOS and endometriosis
These findings don’t mean pregnancy is unsafe for people with both conditions, but they do mean that pregnancies should be monitored more closely. If you have both diagnoses and become pregnant, making sure your obstetric team knows about both conditions is important. Extra surveillance for clotting risk and placental health can catch problems earlier, when intervention is most effective.
Managing Two Conditions at Once
Treatment gets complicated when two conditions with different hormonal drivers are present together. Hormonal contraceptives, particularly combined pills, are a first-line treatment for both PCOS and endometriosis individually. They suppress ovulation, thin the uterine lining, and reduce androgen levels, which can address symptoms from both conditions simultaneously. But if you’re trying to conceive, that option is off the table, and the treatment paths diverge sharply.
For fertility-focused management, ovulation induction is standard for PCOS, while surgical removal of endometriotic lesions may be recommended for endometriosis-related infertility. A review of surgical approaches found that laparoscopic surgery was effective for removing ovarian cysts and endometrial implants, leading to improved fertility and reduced chronic pelvic pain in women with both conditions.14Brazilian Journal of Implantology and Health Sciences. Polycystic Ovary Syndrome and Endometriosis: Impact on Fertility and Quality of Life and Surgical Options The risks and benefits of surgery need to be weighed individually, though. Ovarian surgery carries a real risk of reducing ovarian reserve, which is the number of eggs available for future cycles. That risk is particularly relevant when PCOS is also in the picture, because PCOS management may eventually involve IVF, where a strong egg supply matters.
Lifestyle management overlaps meaningfully for both conditions. Regular exercise and a diet that helps manage insulin levels can improve metabolic markers in PCOS and reduce systemic inflammation relevant to endometriosis. Anti-inflammatory dietary approaches have shown some promise for endometriosis pain management, and they align with the insulin-sensitizing diets often recommended for PCOS. This is one area where having both conditions does not double the treatment burden, since the same lifestyle adjustments can benefit both.
When Symptoms Do Not Fit Neatly Into One Box
One of the most practical things to take away from the co-occurrence research is a greater willingness to question a single diagnosis when symptoms linger or evolve. PCOS and endometriosis each have textbook presentations, but real patients rarely match textbooks. A person with PCOS who develops progressive, worsening pain with each cycle deserves a workup for endometriosis. A person being treated for endometriosis whose periods remain very irregular or who develops metabolic symptoms should have PCOS considered.
The quality-of-life impact of having both conditions is severe. The clinical data showing dramatically worse quality-of-life scores in women with both diagnoses compared to those with endometriosis alone is striking and should motivate thorough evaluation.2PubMed Central. Epidemiological study and clinical consequences of endometriosis and PCOS co-occurrence in a clinical population of women Missing one half of the picture means missing treatment opportunities that could substantially improve daily life. If your current diagnosis and treatment aren’t fully accounting for your symptoms, raising the possibility of a second condition with your doctor is a reasonable and evidence-backed step.