What was shown
The clinical scale of PCOS — 8-13% of women of reproductive age globally, up to 20-25% in some ethnic groups — and the role of elevated LH in driving the syndrome and complicating stimulation. The 2023 international PCOS guideline, the revised Rotterdam criteria, and a real-world look at NHSU caseload showing how often PCOS sits behind anovulatory infertility.
Key findings
PCOS accounts for around 70% of anovulatory infertility cases. Elevated LH is both a diagnostic marker and a driver of theca-cell hyperandrogenism. Stimulation pitfalls in PCOS — premature LH surge, OHSS risk, asynchronous follicular growth — are largely predictable from baseline LH and ovarian morphology. The 2023 guideline reframes diagnosis and management around the revised Rotterdam criteria with stricter ultrasound thresholds.
What this means in practice
Lock the diagnosis using the revised Rotterdam criteria before designing the protocol. Choose an antagonist protocol with low-dose start and individualised trigger for PCOS to manage OHSS risk while preserving oocyte maturation. Combine inositol, metformin and lifestyle where indicated; treat LH excess as a parameter to manage, not to ignore.
Caveats
Rotterdam ultrasound thresholds have changed — older diagnoses may need revisiting. LH levels in PCOS are not always elevated; phenotype A, B, C, D behave differently. PCOS is heterogeneous; one stimulation protocol does not fit all four phenotypes.
The speaker foregrounds PCOS heterogeneity: phenotypes A, B, C, D behave differently, and LH levels are not always elevated — so a single protocol for all four phenotypes is bound to lose to an individualised one.
The practical emphasis is managing, not ignoring, the LH excess: an antagonist protocol with a low-dose start, an individualised trigger (agonist to prevent OHSS), plus inositol, metformin and lifestyle modification where indicated.
The upshot: in PCOS, LH is both a diagnostic marker and a driver of hyperandrogenism; sound stimulation is built on the revised Rotterdam 2023 criteria and on controlling LH-driven risks, not on a "standard" regimen.
PCOS is the most common endocrine disorder of reproductive age (up to 8–13% of women). The revised Rotterdam criteria and the 2023 international guideline refined the diagnosis: emphasis on hyperandrogenism, oligo-/anovulation and ovarian morphology, with mandatory exclusion of other causes. AMH is regarded as an auxiliary marker of polycystic morphology.
A key link in the pathogenesis is the increased amplitude and frequency of LH pulses, which drives theca cells to overproduce androgens. LH-driven hyperandrogenism closes a vicious circle: selection of the dominant follicle is disrupted, small antral follicles accumulate, and anovulation becomes entrenched.
The practical conclusion is cautious stimulation: low starting doses, antagonist protocols, priority of the GnRH-agonist trigger and a freeze-all strategy to prevent OHSS. A personalized PCOS protocol balances an adequate response against safety, rather than chasing oocyte numbers at any cost.
PCOS affects 8-13% of women of reproductive age and drives 70% of anovulatory infertility. A look at the role of elevated LH in PCOS pathogenesis, the 2023 international guideline, the revised Rotterdam criteria — and what a personalised stimulation pathway looks like in 2026.
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