In a patient with PCOS undergoing IVF, a GnRH agonist trigger rather than hCG trigger is planned to prevent OHSS. The patient has a day-3 AMH of 14.2 ng/mL and AFC of 28. After GnRH agonist trigger, what is the MOST critical immediate intervention to maintain corpus luteum function and prevent luteal phase deficiency?

• A Progesterone vaginal pessaries 400 mg twice daily started on day of trigger
• B Low-dose hCG 1500 IU bolus 35 hours after GnRH agonist trigger
• C Estradiol valerate 6 mg oral daily from day of trigger
• D Modified luteal support with progesterone plus estradiol plus hCG 500 IU on days 1 and 4 after trigger ✓

Explanation

GnRH agonist trigger causes a brief LH/FSH surge followed by rapid luteolysis, resulting in profound luteal phase deficiency compared to hCG trigger. For freeze-all cycles (segmented IVF), this is not an issue. For fresh embryo transfer after GnRH agonist trigger, intensive luteal phase support is required: the ESMO/ESHRE-endorsed approach includes progesterone plus estradiol plus a small hCG 'rescue' dose (500 IU on days 1 and 4 post-oocyte retrieval) to maintain corpus luteum function. This 'modified luteolysis' protocol maintains acceptable ongoing pregnancy rates. Low-dose hCG alone (option B, the Humaidan protocol) is also used but in high-responders carries residual OHSS risk. The combination in option D is the safest comprehensive approach.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

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Written and medically reviewed by the StethoPrep medical team.