HCG trigger versus GnRH agonist trigger in PCOS patients undergoing IVF cycles: frozen embryo transfer outcomes

The use of Gonadotrophin releasing hormone agonist (GnRHa), with freeze-all strategy followed by frozen embryo transfer (FET) has been found to eliminate the risk of ovarian hyperstimulation syndrome (OHSS) in women with polycystic ovarian syndrome (PCOS) undergoing IVF cycles. However, physicians still hesitate to routinely use GnRHa as a trigger, replacing human chorionic gonadotrophin (hCG), for concerns of compromised cycle outcome. We aimed to evaluate outcomes following the transfer of embryos in FET cycles obtained from GnRHa trigger in comparison with hCG trigger in PCOS patients of Asian origin.

Prospective observational cohort study. 210 PCOS patients undergoing IVF in an antagonist protocol who were randomized in the previous study (to evaluate if GnRHa trigger is a better alternative than hCG in PCOS patients to prevent OHSS; Group A: GnRHa trigger (n=92)] and Group B: hCG trigger (n=101)], were followed up in FET cycles to assess the outcomes.

The odds of cumulative live birth rate per stimulation cycle favors GnRHa trigger against the hCG trigger [OR=2.15; (CI 1.2-3.83); p=0.008]. A significantly higher number of mature oocytes (19.1±11.7 versus 14.1±4.3; p<0.001) and blastocysts (4.2±1.63 versus 3.26±1.22; p<0.001) were available in the GnRHa group as compared to the hCG group.

The cumulative live birth rate was better following transfer of frozen-thawed embryos generated from GnRHa-triggered cycles compared to hCG trigger. Hence, in PCOS undergoing IVF, as a good practice point, hCG trigger should be replaced by a GnRHa trigger with vitrification of all embryos followed by FET.