Assess, diagnose and manage the patient presenting with polycystic/metabolic ovarian syndrome (PMOS)

In one line

PMOS (previously PCOS) is a lifelong metabolic-reproductive syndrome diagnosed on the Rotterdam criteria after exclusion of mimics; beyond making the diagnosis, the task is to stratify the woman's metabolic and oncological risk and match therapy to her stated goal — cycle control, hyperandrogenism, fertility or long-term cardiometabolic protection.

Assessment

The Intermediate groundwork — what PMOS is, the basic Rotterdam triad, the hormonal axis, and the everyday contraceptive choices used to control cycles — is assumed; the work here is getting the diagnosis secure, the phenotype named, and the risk profile complete.

Diagnosis (2023 international guideline, Rotterdam framework). In an adult, two of three: (i) clinical and/or biochemical hyperandrogenism; (ii) ovulatory dysfunction; (iii) polycystic ovarian morphology (PCOM) on ultrasound or a raised AMH — provided you have excluded other causes.

• Biochemical hyperandrogenism — measure total and free testosterone; estimate free testosterone via the calculated free androgen index (good-quality assays, with SHBG). If total testosterone is markedly raised (a common viva cut-off is >5 nmol/L) or onset is rapid/virilising, you are obliged to exclude an androgen-secreting tumour and non-classic congenital adrenal hyperplasia (17-OHP), and Cushing's where the phenotype fits. DHEAS and androstenedione are second-line.
• Ovulatory dysfunction — cycles outside ~21–35 days, or persistent oligo/amenorrhoea. Always check TSH, prolactin and FSH to exclude thyroid disease, hyperprolactinaemia and primary ovarian insufficiency before settling on PMOS.
• PCOM — on transvaginal scan the threshold is now follicle number per ovary ≥20 (2–9 mm) in at least one ovary; serum AMH may be used as an alternative to ultrasound in adults. The guideline deliberately gives no single universal AMH cut-off — laboratories must use population- and assay-specific thresholds, so quote AMH as supportive, never as a hard number in the exam.
• Adolescents — require both hyperandrogenism and ovulatory dysfunction; ultrasound and AMH must not be used to diagnose PCOM within 8 years of menarche (low specificity). Label "at risk" and reassess at full reproductive maturity.

Name the phenotype

Rotterdam's "two of three" generates four phenotypes, and the phenotype, not the label "PMOS", predicts her metabolic trajectory and shapes counselling. The mechanism that links them is that the hyperandrogenic, anovulatory axis carries the insulin-resistance load — so phenotype severity tracks the presence of hyperandrogenism plus anovulation, not the ovarian appearance.

The clinical corollaries: A and B carry the heaviest cardiometabolic and endometrial burden and warrant the most aggressive metabolic surveillance; phenotype B is the trap — a "normal scan" tempts the junior to reassure, but she is metabolically a classic patient; phenotype D is the one to reassure proportionately on metabolic risk while still protecting the endometrium because she is anovulatory; phenotype C shifts the management centre of gravity from endometrial protection toward androgen control. Name the phenotype explicitly — "this is Rotterdam phenotype A" — and the rest of the plan follows from it.

Why "metabolic" is in the name — and where the screen misleads

Having made the diagnosis, screen every woman regardless of BMI — the lean, normal-weight PMOS woman is the one most often missed, because insulin resistance in PMOS is partly intrinsic (independent of adiposity), so a normal BMI does not exonerate her.

• A 75 g OGTT is the most accurate glycaemic test: HbA1c and fasting glucose both systematically miss impaired glucose tolerance in PMOS, where the lesion is post-prandial. It is the most commonly omitted test. Repeat every 1–3 years by risk; bring it forward preconception and in pregnancy.
• Fasting lipid profile at diagnosis, annual blood pressure, weight/waist, and validated screening for depression and anxiety (the psychological morbidity is part of the syndrome, not incidental). Ask about snoring/daytime somnolence and screen for obstructive sleep apnoea where symptomatic.
• Do not order HOMA-IR or fasting insulin to "confirm" insulin resistance. Insulin resistance is not a diagnostic criterion, and the surrogate indices (HOMA-IR, fasting insulin, Belfiore) are assay-dependent and discordant — clinical measurement of insulin resistance is explicitly not recommended. You manage the downstream metabolic consequences (glucose, lipids, BP, weight), not a HOMA number. Sending a HOMA-IR is over-investigation.

This metabolic workup, pitched to the phenotype, completes the assessment.

Management

Frame every answer as immediate (this consultation) → ongoing → long-term, and anchor it to her goal and her phenotype.

Immediate — counsel, screen, set the frame. Confirm the diagnosis, name the phenotype, give the phenotype-weighted metabolic screen above, and address weight stigma explicitly: offer best-practice care regardless of weight, acknowledging weight as a partly non-modifiable risk and avoiding unrealistic targets. Lifestyle (nutrition + activity) is first-line for all phenotypes; modest weight loss (~5%) improves ovulation, androgens and glycaemia, but lifestyle alone is not assumed to normalise weight.

Ongoing — match drug to goal.

Phenotype- and goal-specific nuance

• The CHC choice is not generic. "Any low-dose CHC" is the default, but the consultant judgement is the trade-off: a more anti-androgenic progestin (drospirenone, cyproterone, dienogest) helps the hirsute phenotype-A/C woman but carries the higher VTE signal, so 35 µg EE + cyproterone acetate is explicitly second-line and the cyproterone-containing pill is reserved, not reached for first. Balance efficacy, metabolic risk, side-effects, cost and SA availability — weigh VTE risk against androgen benefit rather than reciting a brand.
• Metformin: who, and how much benefit. Reserve metformin for the metabolic indication — it is recommended where BMI ≥25 for anthropometric and metabolic outcomes — not as a fertility drug and not for every PMOS woman. It is the SA-pragmatic choice over inositol (EML-listed, cheap, familiar), which has greater metabolic evidence; inositol is low-harm but has no recommendable dose or form and no proven clinical benefit. Counsel the GI side-effect load up front and titrate.
• Anti-androgen sequencing. Spironolactone is added after ≥6 months of CHC because hair-cycle kinetics mean hirsutism improvement is slow; combining it with the CHC also covers its teratogenicity (feminisation of a male fetus) — never give an anti-androgen without reliable contraception. Eflornithine and mechanical/laser methods are adjuncts, not substitutes.
• Obesity pharmacotherapy and metabolic surgery. GLP-1 receptor agonists and bariatric/metabolic surgery follow general-population obesity guidance, not a PMOS-specific protocol. The easily-missed catch is that fertility returns as weight falls — counsel contraception, and after metabolic surgery defer pregnancy ~12–18 months through the active-weight-loss/nutritional-deficiency window, switching off any oral contraceptive whose absorption malabsorptive surgery compromises in favour of a non-oral method.

Ovulation induction — the named-regimen detail

For ovulation induction, letrozole is first-line, with the safety counselling that it is used off-label for this indication in many settings and that trial data show higher live-birth and ovulation rates than clomiphene without an established teratogenic signal. In the pivotal head-to-head RCT, cumulative live birth was 27.5% with letrozole vs 19.1% with clomiphene (rate ratio 1.44, 95% CI 1.10–1.87) and ovulation 61.7% vs 48.3%.

The mechanistic contrast: clomiphene is a selective oestrogen-receptor modulator that blocks hypothalamic oestrogen feedback to raise FSH — but its anti-oestrogenic action on endometrium and cervical mucus is exactly why ovulation rates outrun pregnancy rates. Letrozole is an aromatase inhibitor that lowers oestrogen transiently without occupying endometrial receptors, sparing the endometrium — the proposed reason live-birth is higher. Practical regimen logic: start low and step up only on a non-response, monitor the first cycle (follicle-tracking) to catch multifollicular recruitment and the resulting multiple-pregnancy and OHSS risk, and define resistance before escalating. Where clomiphene is used, adding metformin raises ovulation and clinical-pregnancy rates but has not been shown to increase live birth over clomiphene alone; in obese women specifically, metformin monotherapy is inferior to clomiphene, so reserve it as adjunct rather than substitute. Gonadotrophins (low-dose step-up, intensive monitoring for OHSS/multiples) and laparoscopic ovarian drilling (mono-ovulatory, no OHSS/multiple-pregnancy excess, but a surgical/anaesthetic event with a small risk of ovarian-reserve damage and adhesions) are third-line for clomiphene/letrozole-resistant anovulation; drilling earns its place in the woman who needs a laparoscopy anyway or who cannot attend for gonadotrophin monitoring — a realistic SA consideration.

Long-term — the syndrome outlives the fertility window

PMOS confers a markedly raised risk of endometrial hyperplasia and endometrial cancer (chronic unopposed oestrogen from anovulation) — pooled observational data put the endometrial-cancer odds ratio at roughly 2.8 overall, rising to ~4 in women under 54 — so ensure regular endometrial shedding: a minimum of ~4 withdrawal bleeds/year, achieved with cyclical progestogen (e.g. medroxyprogesterone acetate 10 mg daily for 12–14 days every 1–3 months), a CHC, or the LNG-IUS (also a contraceptive, and the option with the strongest direct endometrial protection — a reasonable default in the woman who also wants contraception or has already shown hyperplasia). The phenotype tells you who needs this most: every anovulatory phenotype (A, B, D) needs scheduled shedding; the ovulatory phenotype C needs it least. Investigate persistent intermenstrual/heavy bleeding or a thickened endometrium with pelvic ultrasound ± biopsy; routine asymptomatic endometrial screening is not recommended.

Manage the lifelong cardiometabolic risk actively, not passively — the 2023 guideline elevates PMOS to a recognised cardiovascular-risk state, so the woman is handed a primary-care metabolic follow-up plan, not discharged once her cycles are controlled. This underlies the elevated type-2-diabetes and cardiovascular burden, and dovetails with the high baseline metabolic-syndrome prevalence in South African women — the lifestyle, glucose-surveillance and BP-control limbs matter at least as much as the hormonal ones, and arguably outlast them. Where contraception is needed alongside metabolic disease, eligibility is set out in contraception-in-high-risk-women.

Preconception and pregnancy. Because PMOS is a high-risk pregnancy state for gestational diabetes and hypertensive disease, optimise before conception: a preconception 75 g OGTT (fasting glucose/HbA1c will under-detect), weight optimisation, folate, and a plan for early pregnancy glucose screening with a repeat OGTT at the standard 24–28 weeks (earlier if the preconception test was abnormal). Note the evidence below that metformin is not a routine GDM-prevention drug — do not promise it will stop her getting GDM.

The evidence & the controversy

The 2023 International Evidence-based Guideline (Monash-led, co-published in JCEM, EJE, Human Reproduction and Fertility and Sterility; ~254 recommendations/practice points) is the reference standard and supersedes ad-hoc Rotterdam application. Several positions warrant a defence.

First, AMH as an alternative to ultrasound for PCOM is evidence-based but assay-dependent — the guideline pointedly refuses a universal cut-off, so "AMH >X ng/mL diagnoses PMOS" over-reads the evidence; prospective work (e.g. the HARMONIA validation) is still refining assay-specific morphology thresholds. Second, letrozole over clomiphene as first-line ovulation induction is now firm: pooled RCT data show higher ovulation and live-birth rates, reversing decades of clomiphene-first practice. Third, the guideline's refusal to endorse HOMA-IR / insulin-resistance measurement follows from the biology: insulin resistance is mechanistically central but clinically unmeasurable with available assays, so it is not a criterion and you treat its consequences.

The genuinely contested ground is metformin in pregnancy. The guideline states metformin has not been shown to prevent gestational diabetes or hypertensive disease in pregnancy, and that long-term offspring effects remain uncertain — so the once-popular "continue metformin through pregnancy to prevent GDM" is no longer defensible without nuance. The largest PMOS-specific RCT (PregMet2) found metformin did not prevent GDM (25% vs 24%, OR 1.09) and only non-significantly reduced its composite of late miscarriage/preterm birth (5% vs 10%, OR 0.50, 95% CI 0.22–1.08); only a post-hoc three-trial pooled analysis reached significance (OR 0.43, 95% CI 0.23–0.79). In non-diabetic obese pregnant women without PMOS, the EMPOWaR trial showed no effect on birthweight. The honest position is therefore that metformin is not a routine GDM-prevention drug in pregnancy; the late-miscarriage/preterm signal is hypothesis-generating, not practice-changing.

A second live debate is the PCOS→PMOS rename itself: proponents argue "polycystic ovary" misleads (many women have no cysts; the ovarian appearance is the least clinically important feature, and the phenotype table shows why — morphology is the criterion that least predicts metabolic risk) and that "metabolic" reframes the syndrome around its dominant long-term morbidity. There are two defensible readings: the rename improves risk-focused care, but it also risks under-emphasising the reproductive phenotype — holding both is more honest than picking a side. The thinness of the evidence base (most recommendations rest on low-to-moderate-certainty data) is itself a fair point of critique (maternity-statistics-critical-appraisal).

Landmark trials & key evidence

The studies below underpin ovulation-induction and metformin decisions. The direction and the number matter, not just the title.

The umbrella reference for everything above is the 2023 International Evidence-based Guideline (254 recommendations); note its own caveat that most recommendations rest on low-to-moderate-certainty evidence — a fair qualification on the strength of the guidance.

Reading the numbers

The key trials translate into effect sizes that hold up at the bedside:

• Letrozole over clomiphene (PPCOS II). The absolute difference in cumulative live birth is 27.5% − 19.1% = 8.4 percentage points, an absolute risk increase of 0.084. The number needed to treat to gain one extra live birth is therefore NNT = 1/0.084 ≈ 12 — roughly one additional baby for every twelve women treated with letrozole rather than clomiphene. That single number is the strongest argument for first-line letrozole.
• Metformin is not a fertility drug (PPCOS I). Metformin's live-birth rate (7.2%) was less than a third of clomiphene's (22.5%), and adding metformin to clomiphene (26.8%) did not beat clomiphene alone — the result that retired "metformin for fertility" and explains why it survives only as a metabolic intervention and a clomiphene adjunct in specific (e.g. higher-BMI-with-caveats) contexts.
• Metformin in pregnancy (PregMet2). The GDM rates were essentially identical (25% vs 24%) — an absolute difference of ~1 percentage point, well within noise — which is why "continue metformin to prevent GDM" cannot be defended; the only significant signal came from a post-hoc pooled analysis, the weakest design tier, so present it as hypothesis-generating.

On the strength of the evidence overall: the fertility recommendations (letrozole) rest on good RCT data, while much of the metabolic and long-term guidance rests on low-to-moderate-certainty evidence — and that asymmetry is itself worth stating when weighing the evidence.

Exam traps & red flags

• Diagnosing on ultrasound alone, or in an adolescent. PCOM is one of three criteria, not a diagnosis; never use scan/AMH within 8 years of menarche.
• Down-staging phenotype B because the scan is normal. Hyperandrogenism + anovulation is PMOS without PCOM, and it carries near-classic metabolic risk — a normal ovary is not reassurance.
• Sending a HOMA-IR / fasting insulin to "confirm" insulin resistance. Not a diagnostic criterion; the assays are unreliable; clinical measurement is not recommended. Treat the downstream glucose/lipid/BP, not a HOMA number.
• Skipping the exclusions. No TSH/prolactin/FSH, no 17-OHP when androgens are high, no cortisol screen in a Cushingoid woman — and missing the rapidly virilising picture that signals an androgen-secreting tumour (the must-not-miss).
• Forgetting the OGTT. Screening on HbA1c/fasting glucose alone misses impaired glucose tolerance; the 75 g OGTT is the guideline test, irrespective of BMI — including in the lean woman and preconception.
• Clomiphene-first for infertility. Outdated — letrozole is first-line; know it is often off-label.
• Promising metformin will prevent her GDM. It will not (PregMet2); use it for the metabolic indication, not as antenatal GDM prophylaxis.
• Neglecting endometrial protection. Long-standing oligo/amenorrhoea without progestogen/CHC/LNG-IUS is unopposed oestrogen — investigate abnormal bleeding, don't just reassure.
• Anti-androgen without contraception. Spironolactone/cyproterone are teratogenic — never start one without reliable contraception, and never as monotherapy before ≥6 months of CHC.
• Telling every woman to "just lose weight." Reproduces weight stigma the guideline explicitly warns against; offer treatment regardless of weight and avoid unrealistic targets.
• Quoting a hard AMH cut-off as diagnostic — the guideline deliberately doesn't endorse one.
• Forgetting fertility returns with weight loss — counsel contraception when starting a GLP-1 agonist or after metabolic surgery, and defer pregnancy ~12–18 months post-surgery.

Worked viva — how to structure the answer

Consider a 24-year-old, BMI 33, oligomenorrhoea since menarche, hirsutism, trying to conceive for 14 months; total testosterone mildly raised, TSH and prolactin normal, scan shows ≥20 follicles per ovary. The management runs:

1. Frame and phenotype it — this is PMOS, Rotterdam phenotype A (hyperandrogenism + anovulation + PCOM) — the phenotype with the highest metabolic and endometrial-cancer risk — presenting with anovulatory infertility.
2. Secure the diagnosis — confirm the exclusions are done (TSH, prolactin, FSH normal; 17-OHP if androgens were high; exclude a tumour if rapidly virilising), and confirm there is no other infertility factor (semen analysis, tubal patency) before treating the ovary.
3. Screen to the phenotype — 75 g OGTT (not HbA1c), fasting lipids, BP, weight/waist, mood screen; counsel that lifestyle and ~5% weight loss are first-line and improve ovulation.
4. Match therapy to the stated goal — her goal is pregnancy, so first-line ovulation induction is letrozole, not clomiphene; counsel its off-label status, monitor the first cycle for multifollicular response, and define resistance before escalating to gonadotrophins or ovarian drilling.
5. The evidence — PPCOS II for letrozole (live birth 27.5% vs 19.1%, NNT ≈ 12), PPCOS I for why metformin is not a fertility drug, and the metabolic-evidence asymmetry.
6. The long game — endometrial protection between conception attempts, the high-risk-pregnancy plan (preconception and 24–28-week OGTT; metformin won't prevent GDM), and lifelong cardiometabolic follow-up handed to primary care.
7. Hold the controversy — both sides of the PCOS→PMOS rename, conceding that most non-fertility recommendations rest on low-to-moderate-certainty evidence.

Evidence anchors

• Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of PCOS — JCEM
• Same guideline recommendations — European Journal of Endocrinology
• 2023 guideline recommendations (open-access full text) — PMC10505534
• Recommendations from the 2023 International Evidence-based Guideline for PCOS — ASRM practice guidance
• Utility of serum AMH measurement as part of PCOS diagnosis — PMC11257749
• Prospective validation of an AMH cutoff for polycystic ovarian morphology: HARMONIA study — Fertility and Sterility
• Comparative outcomes of letrozole versus clomiphene citrate for ovulation induction in PCOS: systematic review and meta-analysis — PMC13055185
• Letrozole versus clomiphene for infertility in the polycystic ovary syndrome (PPCOS II) — Legro et al, NEJM 2014
• Clomiphene, metformin, or both for infertility in the polycystic ovary syndrome (PPCOS I) — Legro et al, NEJM 2007
• Randomized controlled trial of preconception interventions in infertile women with PCOS (OWL-PCOS) — Legro et al, JCEM 2015
• Insulin-sensitising drugs (metformin, rosiglitazone, pioglitazone, D-chiro-inositol) for women with PCOS — Cochrane (Morley et al, 2017)
• Inositol for subfertile women with polycystic ovary syndrome — Cochrane (Showell et al, 2018)
• Use of metformin to treat pregnant women with PCOS (PregMet2) — Løvvik et al, Lancet Diabetes & Endocrinology 2019
• Effect of metformin on maternal and fetal outcomes in obese pregnant women (EMPOWaR) — Chiswick et al, Lancet Diabetes & Endocrinology 2015
• Risk of endometrial, ovarian and breast cancer in women with PCOS: systematic review and meta-analysis — Barry et al, Human Reproduction Update 2014
• Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of PCOS — Eur J Endocrinol (DOI)
• RCOG Green-top Guideline No. 33 — Long-term Consequences of Polycystic Ovary Syndrome
• Review: Metabolic Syndrome in Black South African Women — PMC5398178