Polycystic ovary syndrome in adolescents — branching viva

Stem

The examiner will test whether you can reason through adolescent PCOS diagnosis under pressure, avoiding premature labelling while identifying genuine disease. [1] [2]

Branch 1 — Diagnostic criteria

Examiner: A 16-year-old has irregular cycles and an ultrasound showing polycystic ovaries. Does she have PCOS? [4] [2]

Strong answer: Not necessarily. Rotterdam requires two of three criteria: oligo-/anovulation, hyperandrogenism, and polycystic ovarian morphology. In adolescents, ultrasound morphology alone must not anchor the diagnosis because multifollicular ovaries are physiologically normal in this age group. I need to confirm persistent menstrual dysfunction beyond two years post-menarche and document objective hyperandrogenism, clinical or biochemical, before applying the label. I would also exclude mimics. [4] [2] [1]

Examiner: What if her cycles have been irregular since menarche two years ago? [2]

Strong answer: Two years post-menarche is the threshold where persistent irregularity becomes pathological rather than physiological. If she is at the two-year mark, I would observe for persistence and document objective hyperandrogenism before diagnosing. The Pena 2025 adolescent recommendations support a cautious, time-based approach rather than a single-visit label. [2] [1]

Branch 2 — Excluding mimics

Examiner: What mimics must you exclude before confirming PCOS? [3]

Strong answer: Non-classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency — screen with a basal 17-hydroxyprogesterone level. Thyroid dysfunction with TSH and free T4. Hyperprolactinaemia with a prolactin level. Cushing syndrome if there are Cushingoid features. And androgen-secreting tumour if virilisation is rapid or testosterone is very high — typically above 5 to 6 nmol per litre. [3] [2]

Examiner: The 17-OHP comes back mildly elevated. What next? [3]

Strong answer: A mildly elevated basal 17-OHP requires ACTH stimulation testing to confirm or exclude non-classic CAH. If positive, the diagnosis is CAH, not PCOS, and management shifts to glucocorticoid replacement. If negative, I return to the PCOS diagnostic pathway. [3]

Branch 3 — Management decisions

Examiner: Diagnosis confirmed. She is obese with BMI 31, irregular cycles, and acne. What is your management? [5] [3]

Strong answer: Lifestyle modification is first-line for every patient regardless of phenotype. I recommend 150 minutes or more of moderate-intensity exercise per week, sleep optimisation, and a sustainable healthy eating pattern targeting 5 to 10% weight reduction. I frame this around health behaviours and function, not weight, to avoid triggering disordered eating in this vulnerable population. I add a combined oral contraceptive pill for menstrual regulation, endometrial protection, and its mild antiandrogen effect on acne. [5] [3]

Examiner: Should you start metformin? [6]

Strong answer: Metformin is an adjunct, not first-line. The Hoeger trial showed metformin plus lifestyle modestly improved menstrual cyclicity and insulin sensitivity in obese adolescent women, but the effect was adjunctive. I would consider metformin if she has impaired glucose tolerance on OGTT or significant insulin resistance. It does not reliably treat hirsutism or provide endometrial protection. [6] [3]

Branch 4 — Mental health

Examiner: She scores positive on a depression screen. How does this change management? [7]

Strong answer: Mental health is a core pillar, not an optional add-on. Up to 50% of women with PCOS have anxiety or depression. I assess suicide risk in detail, initiate a safety plan if needed, and arrange psychology referral. Untreated mental health worsens adherence, lifestyle engagement, and every other outcome. I continue the PCOS pharmacotherapy because treating the metabolic condition can itself improve emotional distress, as Cinar and colleagues showed with COCP. [7]

Branch 5 — AMH and biomarkers

Examiner: A colleague suggests checking anti-Mullerian hormone to confirm the diagnosis. What do you say? [8] [1]

Strong answer: I would not use AMH as a diagnostic biomarker in adolescents. The 2024 systematic review by van der Ham and colleagues found insufficient diagnostic accuracy for AMH to replace standard criteria, and the Pena 2025 adolescent recommendations do not endorse it for this age group. AMH is elevated in PCOS on average, but the overlap with normal adolescents is too wide for reliable individual diagnosis. [8] [1]

Examiner extras

• Always state lifestyle first before any pharmacotherapy in your opening management answer. [5]
• The single most testable adolescent point is that ultrasound alone does not diagnose PCOS. [2]
• Never prescribe spironolactone without confirming reliable contraception — it is teratogenic. [3]
• If rapid virilisation appears at any point, switch from PCOS reasoning to tumour exclusion. [2]