PCOS vs Endometriosis: Key Differences, Overlap and Diagnosis

• PCOS is a hormonal-metabolic condition (high androgens, insulin resistance, irregular ovulation); endometriosis is an inflammatory condition of misplaced endometrial-like tissue. They are different diseases.
• The simplest clue: PCOS is usually about irregular periods, acne, excess hair and weight changes and is typically not painful; endometriosis is usually about progressively worsening period pain, pelvic pain and pain during sex.
• PCOS is diagnosed mainly through symptoms, blood hormone tests and ultrasound (Rotterdam criteria). Endometriosis is diagnosed through symptom history, examination, expert ultrasound or MRI, and sometimes laparoscopy.
• Both can reduce fertility, but through different mechanisms — PCOS through irregular ovulation, endometriosis through scarring and inflammation. Both are treatable.
• A small number of women have both. If your symptoms do not fit one neat box, ask your gynaecologist to assess for both rather than settling for a single label.

PCOS (polycystic ovary syndrome) is a hormonal and metabolic condition. The core features are higher-than-usual levels of male-type hormones (androgens), irregular or absent ovulation, and often insulin resistance — where the body has to produce extra insulin to keep blood sugar normal. Doctors diagnose it using the Rotterdam criteria, which require at least two of three features: (1) irregular or absent ovulation (long cycles over 35 days, fewer than 9 periods a year, or no periods); (2) signs of high androgens — either visible (acne, excess facial or body hair, scalp hair thinning) or on a blood test; and (3) polycystic-looking ovaries on ultrasound. The 2023 international PCOS guideline raised the ultrasound threshold to 20 or more follicles per ovary on modern high-resolution scanners. Crucially, other causes (thyroid problems, high prolactin, certain adrenal conditions) must be ruled out first. Despite the name, PCOS is not really about "cysts" — those follicles are a sign, not the disease itself.

Endometriosis is a completely different beast. Here, tissue similar to the lining of the uterus grows in places it should not — on the ovaries, the lining of the pelvis, the bowel or bladder surface. This tissue responds to the menstrual hormones each month, bleeds, and triggers inflammation, scarring and adhesions. The result is pain — often progressive, often debilitating. Our deeper explainer on what endometriosis is walks through the stages and causes in detail.

In short: PCOS is a hormone-and-metabolism condition; endometriosis is an inflammation-and-tissue condition. They can occasionally coexist, but they are not the same thing.

• PCOS — typical symptoms: irregular, infrequent or absent periods; acne (often jaw and chin); excess hair on the face, chest or abdomen (Hirsutism in India: Causes, Tests, Treatment and Laser Guide); scalp hair thinning; weight gain around the waist; dark velvety skin patches in the neck, armpits or groin (acanthosis nigricans, a sign of insulin resistance); difficulty conceiving due to irregular ovulation.
• PCOS — usually NOT a feature: cyclical, worsening pelvic pain. PCOS is generally not a painful condition.
• Endometriosis — typical symptoms: period pain that gets worse over the years and is not fully relieved by ordinary painkillers; deep pain during or after sex (Painful Sex (Dyspareunia): Causes & Treatment in India); pelvic pain that can be present even outside periods; painful bowel movements or urination around periods; sometimes heavy bleeding; difficulty conceiving.
• Endometriosis — usually NOT a feature: acne, excess facial hair or other signs of high androgens. Endometriosis does not raise male-type hormones.
• Where they confuse people: both can cause heavy or irregular bleeding and both can affect fertility, so the overlap is real — but the presence of androgen signs points to PCOS, while progressive cyclical pain points to endometriosis.

The diagnostic journeys are quite different, and knowing what to expect helps you avoid unnecessary tests — and avoid being dismissed.

Diagnosing PCOS relies on the Rotterdam criteria (two of three: irregular ovulation, high androgens, polycystic ovaries), after excluding other causes. A typical Indian workup includes a menstrual and symptom history; a clinical check for acne, excess hair and skin changes; height, weight, waist and blood pressure; a pelvic ultrasound (around ₹800–2,500 in private centres, often free or subsidised at government hospitals); and blood tests for testosterone, DHEAS, TSH (thyroid), prolactin and 17-hydroxyprogesterone. Because insulin resistance is central, doctors also check fasting glucose, an OGTT or HbA1c, and a lipid profile. A full hormone panel runs roughly ₹3,500–8,000 privately. For a step-by-step look, see our guide to PCOS treatment options in India.

Diagnosing endometriosis is less about blood tests and more about history, examination and imaging. It starts with a careful symptom history (progressive period pain, pain with sex, cyclical bowel or bladder symptoms, infertility) and a pelvic examination. A skilled transvaginal ultrasound can detect ovarian endometriomas and, increasingly, deeper disease; an MRI of the pelvis (₹6,000–18,000) maps deep disease before surgery. Laparoscopy — keyhole surgery that lets the surgeon see and biopsy the tissue — remains the definitive test when imaging is unclear or surgery is planned. One reason endometriosis is so often missed is that there is no simple blood test for it, which is part of why diagnosis can take years.

Blood tests pull a lot of weight in PCOS but very little in endometriosis — a key practical difference.

In PCOS, hormone tests often show a recognisable pattern: raised total testosterone or free androgen index, sometimes raised DHEAS, a raised LH-to-FSH ratio (less relied upon now), and frequently a high AMH level reflecting a high follicle count. Markers of insulin resistance — raised fasting insulin, abnormal glucose tolerance — and an unfavourable lipid profile are common. Thyroid and prolactin are checked mainly to rule out mimics.

In endometriosis, there is no diagnostic blood test. CA-125 can be raised but is non-specific (it goes up in many benign and serious conditions) and is not recommended for diagnosis. AMH may actually be reduced if endometriomas have damaged the ovaries or after surgery. The takeaway: a normal hormone panel does not rule out endometriosis, and an abnormal one does not confirm it.

Because the underlying problems differ, the treatments barely overlap.

PCOS treatment targets metabolism, androgens and ovulation. The foundation is lifestyle — a balanced, lower-refined-carbohydrate, higher-fibre and protein PCOS diet, regular activity, and where relevant a realistic, gradual approach to weight, since even a 5–10% reduction can restore ovulation. Metformin improves insulin sensitivity; combined oral contraceptive pills regularise cycles, lower androgens and protect the uterine lining; anti-androgens like spironolactone help acne and excess hair. When pregnancy is the goal, ovulation-inducing tablets are first-line — see our guide to PCOS fertility treatment.

Endometriosis treatment targets pain, inflammation and the cyclical stimulation that feeds the disease. Options include NSAIDs (such as mefenamic acid) for pain, hormonal contraceptives taken continuously to suppress periods, progestins like dienogest (now often first-line), a hormonal IUD, and for severe disease, GnRH medicines. Surgical excision via laparoscopy is used for endometriomas, deep disease and fertility. A structured walkthrough is in our endometriosis pain management guide. Note how little the two drug lists share — that is the whole point.

Both conditions can affect fertility, but the mechanism — and therefore the fix — differs.

In PCOS, the main problem is irregular or absent ovulation: if an egg is not released, conception cannot happen. Treatment usually follows a ladder — weight optimisation if needed, then ovulation-inducing tablets, then injections, and IVF if those do not work. Many women with PCOS conceive once ovulation is restored. Pregnancies do carry a somewhat higher risk of gestational diabetes and blood-pressure problems, so PCOS pregnancy care involves closer monitoring.

In endometriosis, infertility is driven by anatomy and inflammation — adhesions distort the tubes and ovaries, endometriomas reduce egg reserve, and the inflamed pelvic environment hampers fertilisation. Treatment depends on age, ovarian reserve and disease severity; for some women surgery plus timed conception works, while for others IVF is more efficient. Our detailed guide on endometriosis and infertility covers the decision-making. Where both conditions coexist, a fertility specialist addresses each in turn.

These two conditions follow very different long-term paths, and Indian women face some specific risks.

PCOS carries a real, lifelong metabolic and cardiovascular risk. Women with PCOS have several times the risk of type 2 diabetes, plus higher rates of fatty liver, sleep apnoea, and mood difficulties. Indian women, who tend to have higher baseline insulin resistance and central fat, are particularly vulnerable — which is why diabetes screening and metabolic care matter even in your twenties and thirties. Infrequent periods also leave the uterine lining unprotected, modestly raising the risk of endometrial overgrowth and cancer over time, which is why doctors recommend regular withdrawal bleeds via the pill, cyclical progestin or a hormonal IUD.

Endometriosis is associated with a small increase in the risk of certain ovarian cancers in long-standing cases, but the absolute risk stays low. The dominant long-term burden is chronic pain and its impact on work, relationships and mental health — which is why ongoing, joined-up care beats episodic painkiller prescriptions. Both conditions are best managed as long-term conditions, not one-off problems.

A small minority of women genuinely have both PCOS and endometriosis. The conditions are independent, so having one does not protect you from the other.

The overlap is where misdiagnosis happens. A woman with PCOS who also has worsening period pain may be told her pain is "just PCOS" (it usually is not — PCOS is not typically painful). A woman with endometriosis who also has acne and weight gain may be steered only toward a PCOS workup. If your symptoms straddle both pictures, the right move is a parallel assessment: a hormone and metabolic panel for PCOS and expert imaging (and sometimes laparoscopy) for endometriosis.

When both are confirmed, treatment is layered — metabolic and ovulation management for PCOS, plus pain and disease control for endometriosis — and fertility planning accounts for both. The single most useful thing you can do is refuse to let one label close the book on the other.

• Periods that are consistently irregular, very far apart (over 35 days), or absent for three months or more.
• Period pain that is getting worse year on year, is not relieved by ordinary painkillers, or makes you miss school, work or daily activities.
• Pain during or after sex, or pain with bowel movements or urination that comes around your periods.
• Pelvic pain that is present even when you are not menstruating, or that has lasted more than six months.
• New or worsening acne, excess facial or body hair, or hair thinning — especially with irregular periods.
• Difficulty conceiving after 12 months of trying (or after 6 months if you are over 35, or if periods are irregular).

If your symptoms are confusing, a tiered approach saves time and money. Start with a general gynaecologist (₹600–2,500 for a consultation) for history, examination, a pelvic ultrasound and baseline bloods. If PCOS is suspected, the path leads to a hormone and metabolic panel and lifestyle, pill, metformin or fertility treatment depending on your goals. If endometriosis is suspected, the path leads to expert imaging and, where needed, MRI or laparoscopy.

Specialist referral is appropriate for difficult cases — an endocrinologist for severe metabolic disease, a dermatologist for stubborn hirsutism or acne, and a reproductive medicine specialist for fertility. Deep or surgical endometriosis is best handled at centres with subspecialist experience, including major teaching hospitals (AIIMS, PGIMER, JIPMER, CMC Vellore, KEM Mumbai) and established private networks. Most standard health policies cover diagnostic workup and laparoscopic surgery; IVF coverage varies, so confirm in advance. Finally, do not underestimate peer support — PCOS support groups and the Endometriosis Society India reduce the isolation both conditions can bring.

• WHO — Polycystic ovary syndrome (fact sheet)
• WHO — Endometriosis (fact sheet)
• 2023 International Evidence-Based Guideline for the Assessment and Management of PCOS (Monash University / ESHRE / ASRM)
• ESHRE — Endometriosis Guideline (2022)
• NHS — Polycystic ovary syndrome
• NHS — Endometriosis
• ACOG — Endometriosis (FAQ)