The trigger is one small injection at the end of stimulation — and most of the cycle outcome rides on it. The talk walks through HCG, GnRH agonist, dual and double trigger strategies, the Vienna consensus 80-95% oocyte yield target, and the practical decisions that connect trigger choice to oocyte maturation in real protocols.
HCG remains the workhorse trigger but extends LH-like activity over 6-7 days, driving the progesterone surge in fresh cycles. Agonist trigger gives a much shorter LH peak (24-28 hours) and a steep luteal-phase drop — needs rescue if transferring fresh. Dual trigger (agonist + HCG) recovers oocyte maturation in cases with low yield-per-follicle ratio. The Vienna consensus oocyte-yield target of 80-95% of antral follicles is a usable lab quality marker.
Match trigger choice to the cycle plan: HCG for fresh transfer with full luteal-phase support; agonist trigger for freeze-all and OHSS risk; dual trigger when prior cycle showed a low yield-to-follicle ratio. Audit your lab against the 80-95% Vienna target and identify whether deviations come from stimulation, trigger timing or aspiration technique.
Empty follicle syndrome can present even with a correctly administered trigger — check LH stick or progesterone in suspicious cases. Trigger timing affects maturation more than dose at modern doses. HMG-derived LH activity does not match recombinant LH or HCG one-to-one.
The trigger is one small injection at the end of stimulation — and most of the cycle outcome rides on it. A practical walk through trigger choice (HCG, agonist, dual, double), the Vienna consensus 80-95% oocyte yield ratio, and what each trigger does to oocyte maturation in real protocols.
