Polycystic ovary syndrome in adolescents — formative SAQs

SAQ 1 — Diagnostic approach to suspected PCOS (10 marks)

A 16-year-old presents with irregular periods (cycles 40–60 days), moderate acne, and a Ferriman-Gallwey score of 8. Menarche was at age 12. Her mother has type 2 diabetes. A pelvic ultrasound reports "polycystic ovaries." The GP has told the family she has PCOS. [2] [4]

Questions

1. State the Rotterdam diagnostic criteria and explain why adolescent-specific modification is required. (4 marks) [4] [2]
2. List the investigations needed to confirm the diagnosis and exclude mimics, with one sentence of justification for each. (4 marks) [3] [1]
3. Explain whether the ultrasound finding alone establishes the diagnosis in this adolescent. (2 marks) [2] [1]

Model answer

Rotterdam criteria and adolescent modification (4). Rotterdam requires two of three: oligo-/anovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology on ultrasound, after exclusion of mimics. Adolescent modification: do not diagnose on ultrasound alone because multifollicular ovaries are physiologically normal in teens; require persistence of ovulatory dysfunction beyond two years post-menarche and objective hyperandrogenism before applying the label. This patient is four years post-menarche, so persistence is met. [4] [2]

Investigations (4). Total and calculated free testosterone or free androgen index to document biochemical hyperandrogenism (SHBG is suppressed by insulin, so free testosterone is more sensitive than total). TSH to exclude thyroid dysfunction as a cause of menstrual irregularity. Prolactin to exclude hyperprolactinaemia. 17-hydroxyprogesterone to exclude non-classic congenital adrenal hyperplasia — the most important mimic. Fasting glucose or HbA1c and a lipid panel for metabolic screening; consider OGTT if BMI is elevated. [3] [1]

Ultrasound alone (2). The ultrasound finding does not establish the diagnosis. Up to 30–40% of healthy adolescent ovaries meet adult PCOM criteria. The Pena 2025 adolescent recommendations and Rosenfield 2015 statement both caution against ultrasound-based diagnosis in this age group. The diagnosis requires persistent menstrual dysfunction and objective hyperandrogenism, both of which this patient may have, but the ultrasound is supportive rather than diagnostic. [2] [1]