Polycystic Ovary Syndrome
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Direct answer
Polycystic ovary syndrome (PCOS) is a common endocrine-metabolic disorder of reproductive-age women marked by oligo-anovulation, hyperandrogenism and polycystic ovarian morphology. Diagnosis follows the Rotterdam criteria — two of the three features once mimics are excluded. Management is lifestyle-first, with letrozole as first-line ovulation induction for infertility, combined hormonal contraception for cycle control, and metformin for metabolic abnormalities.
What you must remember
- Rotterdam criteria (two of three) — oligo- or anovulation, clinical (hirsutism, acne, alopecia) or biochemical hyperandrogenism, and polycystic ovarian morphology; the updated international guideline defines this morphology as 20 or more small follicles (2-9 mm) per ovary and/or an ovarian volume of 10 mL or more, replacing the older 12-follicle cut-off.
- Exclude mimics first — hypothyroidism, hyperprolactinaemia, non-classic congenital adrenal hyperplasia (17-OHP), Cushing's syndrome and androgen-secreting tumours.
- Supportive findings — an LH to FSH ratio above 2, insulin resistance, acanthosis nigricans and obesity; lean PCOS also exists, so weight is not a criterion.
- PCOS is the commonest cause of anovulatory infertility; long-term risks include type 2 diabetes, metabolic syndrome, endometrial hyperplasia from chronic unopposed oestrogen, and mood disorders.
- Lifestyle modification leads management — losing around 5 per cent of body weight commonly restores spontaneous ovulation in overweight women.
- Letrozole is the first-line ovulation induction agent, with better live-birth rates than clomiphene in the international guideline; metformin serves mainly metabolic indications, and laparoscopic ovarian drilling is an option in selected women.
- Combined oral contraceptives or cyclical progestogens regulate cycles, treat hirsutism and protect the endometrium; anti-androgens such as spironolactone may be added with reliable contraception.
Common confusion
Polycystic ovaries on ultrasound are not the same as the syndrome. Many women have multifollicular or polycystic-appearing ovaries without hyperandrogenism or anovulation, and the ultrasound finding alone never makes the diagnosis. Criteria sets also differ — Rotterdam needs two of three features, while the AE-PCOS Society insists hyperandrogenism be present — a favourite distinction in theory exams.
Exam-focused takeaway
Know the Rotterdam two-of-three rule with the updated 20-follicle ultrasound threshold, the exclusion panel for mimics, and letrozole as the current first-line ovulation induction agent — older textbooks that answer clomiphene are out of date. The 5-per-cent weight-loss figure, the LH to FSH ratio as supportive rather than diagnostic, and endometrial protection strategies round off the stems.
Frequently asked questions
What are the Rotterdam criteria for PCOS?
Two of three — oligo or absent ovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology on ultrasound — after excluding other causes.
Which conditions must be excluded before diagnosing PCOS?
Hypothyroidism, hyperprolactinaemia, non-classic congenital adrenal hyperplasia, Cushing's syndrome and androgen-secreting tumours, using TSH, prolactin, 17-OHP and androgens as indicated.
What is the first-line treatment for infertility in PCOS?
Letrozole for ovulation induction, preceded by lifestyle modification. It achieves higher live-birth rates than clomiphene and is the guideline-recommended first line.
Why is metformin used in PCOS?
Chiefly for insulin resistance, impaired glucose tolerance and metabolic benefits, and it may modestly improve cycle regularity. It is not the primary fertility drug.
What are the long-term health risks of PCOS?
Type 2 diabetes, metabolic syndrome, endometrial hyperplasia and carcinoma from chronic anovulation, and higher cardiovascular risk factors — warranting lifelong follow-up.