Polycystic Ovary Syndrome (PCOS)
Hyperandrogenism + ovulatory dysfunction + polycystic ovarian morphology; insulin resistance is the common thread.
Also known as: PCOS, Stein-Leventhal syndrome, polycystic ovaries, functional ovarian hyperandrogenism
Overview
Heterogeneous endocrine disorder of reproductive-age women defined (Rotterdam 2003) by 2 of 3 criteria: oligo- or anovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology on ultrasound — after exclusion of other causes.
Epidemiology
Affects 8-13% of reproductive-age women worldwide; most common endocrinopathy in this group and a leading cause of anovulatory infertility.
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Risk factors
- Family history of PCOS or type 2 diabetes
- Obesity, particularly central adiposity
- Premature adrenarche, low birth weight
- Insulin resistance, metabolic syndrome
Pathophysiology
Insulin resistance with compensatory hyperinsulinemia augments LH-driven ovarian theca cell androgen production and suppresses hepatic SHBG, increasing free testosterone. Elevated LH:FSH ratio impairs follicular maturation, producing arrested antral follicles (the 'polycystic' appearance) and anovulation. Unopposed estrogen exposure raises endometrial cancer risk.
Clinical presentation
Symptoms
- Oligomenorrhea or amenorrhea, typically since menarche
- Hirsutism (upper lip, chin, chest, abdomen, back)
- Acne, androgenic alopecia
- Infertility, recurrent pregnancy loss
- Weight gain, difficulty losing weight
Signs / physical exam
- BMI often elevated; central adiposity
- Acanthosis nigricans (insulin resistance marker)
- Modified Ferriman-Gallwey score ≥4-8 (population-dependent)
- Acne, male-pattern hair thinning
Classic findings
Young woman with irregular menses, hirsutism, acne, and obesity; ultrasound with ≥20 follicles per ovary or ovarian volume >10 mL.
Differential diagnosis
- Thyroid disease — Menstrual irregularity from hypo- or hyperthyroidism; check TSH
- Hyperprolactinemia — Galactorrhea, amenorrhea; prolactin elevated; consider pituitary adenoma
- Non-classic congenital adrenal hyperplasia (21-hydroxylase deficiency) — Hirsutism with elevated 17-hydroxyprogesterone (early morning, follicular phase >200 ng/dL warrants ACTH stim)
- Cushing syndrome — Central obesity, striae, easy bruising, proximal weakness; abnormal dexamethasone suppression or 24-h urine cortisol
- Androgen-secreting tumor (ovarian or adrenal) — Rapid virilization, total testosterone >150-200 ng/dL or DHEAS markedly elevated; imaging
- Primary ovarian insufficiency — Amenorrhea with elevated FSH and low estradiol
- Hypothalamic amenorrhea — Low BMI, excessive exercise, stress; low FSH/LH and low estradiol
- Idiopathic hirsutism — Regular menses, normal androgens
Diagnostic workup
Diagnostic criteria
Rotterdam criteria (2 of 3): (1) oligo- or anovulation, (2) clinical or biochemical hyperandrogenism, (3) polycystic ovarian morphology on ultrasound — AFTER excluding thyroid disease, hyperprolactinemia, NCCAH, Cushing, and androgen-secreting tumors.
Labs
- Total and free testosterone, SHBG, DHEAS
- TSH, prolactin, 17-hydroxyprogesterone (early-morning follicular)
- Fasting glucose and 2-h OGTT, A1c, lipid panel
- If amenorrhea: FSH, LH, estradiol, urine hCG
- Endometrial biopsy if prolonged amenorrhea or abnormal bleeding (rule out hyperplasia)
Imaging
- Transvaginal pelvic ultrasound: ≥20 follicles per ovary (2-9 mm) and/or ovarian volume >10 mL (per 2018 international guideline)
- Ultrasound morphology is NOT required if irregular menses + hyperandrogenism present; also not used in adolescents within 8 years of menarche
Diagnostic algorithm
| Domain | Finding | Workup |
|---|---|---|
| Ovulatory dysfunction | Oligomenorrhea (<8 cycles/yr) or amenorrhea | Cycle history; progesterone if uncertain |
| Hyperandrogenism (clinical) | Hirsutism, acne, androgenic alopecia | Modified Ferriman-Gallwey score |
| Hyperandrogenism (biochemical) | Elevated total/free testosterone, DHEAS | Morning total + free testosterone, SHBG |
| Polycystic morphology | ≥20 follicles/ovary or volume >10 mL | Transvaginal ultrasound (not in adolescents) |
| Exclude mimics | Normal TSH, prolactin, 17-OHP, cortisol | TSH, prolactin, 17-OHP, dexamethasone suppression if indicated |
Treatment
First-line
- Lifestyle modification: 5-10% weight loss restores ovulation in many; Mediterranean-style diet, 150 min/wk moderate exercise
- Combined oral contraceptive (COCP) — ethinyl estradiol/levonorgestrel, drospirenone, or norethindrone — for menstrual regulation, hirsutism, acne; protects endometrium
- Metformin — improves insulin sensitivity, modest weight loss, restores ovulation in some; first-line for impaired glucose tolerance
Infertility / ovulation induction
- Letrozole — first-line (superior live birth vs clomiphene in PCOS per PPCOS II trial)
- Clomiphene citrate — second-line
- Gonadotropins or IVF if oral agents fail
Hirsutism
- COCP × 6 months before judging response
- Add spironolactone 50-200 mg/day (anti-androgen) — must be paired with reliable contraception (teratogen)
- Eflornithine cream for facial hair; mechanical/laser hair removal as adjunct
Endometrial protection if COCP contraindicated
- Cyclic progestin (medroxyprogesterone 5-10 mg × 10-14 days every 1-3 months)
- Levonorgestrel IUD
Second-line / adjunct
- GLP-1 receptor agonists (semaglutide, liraglutide) for weight loss in obese patients
- Bariatric surgery for BMI ≥35 with comorbidities
- Inositol supplementation — modest evidence, low risk
Complications
- Type 2 diabetes (4x risk), metabolic syndrome, NAFLD
- Endometrial hyperplasia and endometrial carcinoma (from chronic unopposed estrogen)
- Infertility, increased miscarriage rate, gestational diabetes, preeclampsia
- Obstructive sleep apnea, depression and anxiety
- Possible increased risk of cardiovascular disease
PANCE pearls
- Letrozole has replaced clomiphene as first-line for ovulation induction in PCOS-associated infertility.
- Spironolactone is teratogenic (feminization of male fetus) — always combine with effective contraception.
- Adolescent diagnosis requires BOTH hyperandrogenism AND persistent oligomenorrhea (≥2 years post-menarche); ultrasound morphology should not be used.
- Screen all PCOS patients for diabetes with a 2-h OGTT (more sensitive than A1c or fasting glucose alone) every 1-3 years.
- Prolonged amenorrhea (>3 months) warrants either withdrawal bleed induction with progestin or endometrial sampling.
References
- International PCOS Guideline 2023 — 2023 International Evidence-Based Guideline for the Assessment and Management of Polycystic Ovary Syndrome (Teede et al., Fertil Steril 2023)
- ACOG PB 194 — ACOG Practice Bulletin No. 194: Polycystic Ovary Syndrome (Obstet Gynecol 2018)
- PPCOS II — Letrozole versus Clomiphene for Infertility in the Polycystic Ovary Syndrome (Legro et al., NEJM 2014)
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