P-592 Follicular GnRH agonist challenge test (FACT) to predict suboptimal response to GnRH agonist trigger in oocyte cryopreservation cycles
Authors: Avraham S , Youngster M , Gil Y , Yekaternia B , Gat I , Kedem A , Yaakov O , Gidoni Y , Barkat J , Baruchin O , Hourvitz A 
Published: June 2023

Abstract

Study question
Can follicular GnRH agonist administration predict suboptimal response to GnRH agonist trigger assessed by LH levels post ovulation trigger in non-medical oocyte cryopreservation program?

Summary answer
Follicular agonist challenge test (FACT) can serve as an adjunct pre-trigger, intracycle tool to predict adequate response to agonist trigger.

What is known already
Suboptimal response to GnRH agonist ovulation trigger refers to failure to retrieve the expected number of oocytes. It was demonstrated in up to 5.5% of cycles based on relatively low number of studies with heterogenous suboptimal response definitions and prevalence, no clear cut-offs and mainly post - stimulation tools to predict unsuccessful cycle. The most studied variable associated with suboptimal response was LH levels 10-12 hours after ovulation trigger below 12-15IU.

Study design, size, duration
We prospectively recruited all women that underwent non-medical fertility preservation in our tertiary university affiliated medical center between October 2020 and February 2022 and agreed to participate in the study. The study included 91 women.

Participants/materials, setting, methods
On day 2 to menstrual cycle, blood tests were drawn (basal Estradiol/E2, basal FSH/FSH2, basal LH/LH2, Progesterone/P2) and ultrasound (US) was performed. On that evening, the women were instructed to inject 0.2 mg GnRH agonist and arrive for repeated blood workup 10-12 hours later at the next morning, followed by a flexible antagonist protocol. On the morning after ovulation trigger blood tests were again taken and LH levels were compared to FACT LH levels.

Main results and the role of chance
LH levels following agonist ovulation trigger below 15IU occurred in 1.09 % of cycles and were predicted by FACT, r = 0.57, p &lt; 0.001. ROC analysis demonstrated that FACT LH &gt; 42.70 IU would predict LH post trigger of more than 30 IU with 75% sensitivity and 70% specificity, AUC= 0.81. LH levels post trigger also displayed significant positive correlation to basal FSH (r = 0.35, p = 0.002) and basal LH (r = 0.54, p &lt; 0.001). LH levels post ovulation trigger were not associated with total oocytes number or maturity rate. The strongest correlation to the total number of retrieved oocytes and mature oocytes was progesterone level post ovulation trigger (r = 0.74, p &lt; 0.001).

Limitations, reasons for caution
Limitation of our study include the relatively small sample size designed to detect 5% suboptimal proportion and might have been insufficient to allow identification of very rare suboptimal responses

Wider implications of the findings
Suboptimal response to agonist trigger, as assessed with post trigger LH levels is a rare event. FACT could serve as an adjunct pre-trigger, intracycle tool to predict adequate response to agonist ovulation trigger. Future studies should focus on optimization of agonist trigger efficacy assessment and prediction, especially in high responders.

Trial registration number
0304-20-ASF