Should all embryos be frozen in PCOS patients at risk of OHSS?

[Terminology: PCOS was renamed polyendocrine metabolic ovarian syndrome (PMOS) by global consensus in May 2026, published in The Lancet. The International Guideline now uses PMOS/PCOS in its recommendations and will use PMOS alone from 2028. Clinical content, diagnostic criteria and management are unchanged.]

ESHRE (2026) recommendations on OHSS prevention: A GnRH agonist trigger is recommended for final oocyte maturation in women at risk of OHSS, combined with a freeze-all strategy, to minimise the risk of severe OHSS (strong). A freeze-all strategy is recommended to minimise the risk of late-onset OHSS (strong). If a GnRH agonist protocol with hCG trigger is used in high responders, a freeze-all strategy is recommended to decrease late-onset OHSS risk (good practice point). Dopamine agonists are recommended to decrease the risk of early OHSS, particularly in patients receiving hCG for final oocyte maturation (strong, 2025). In patients at risk of OHSS, GnRH agonist for final maturation is probably recommended over hCG where no fresh transfer is performed (conditional). A GnRH agonist trigger with or without freeze-all is preferred over coasting (GPP). Adding hCG to a GnRH agonist as a dual trigger is probably not recommended for high responders (conditional). On thresholds: in GnRH agonist cycles with 19 or more follicles of 11 mm or greater, there is increased OHSS risk and preventative measures are recommended, primarily cancelling the trigger (strong). In antagonist cycles, withholding the agonist trigger may still be considered in women with extremely high response (GPP). Prior to starting stimulation, a risk assessment for high response is advised, to individualise suppression protocol, FSH dose, trigger and transfer strategy (GPP).