P-664 The effect of LH levels on the day of trigger on the oocyte retrieval and maturation rates in GnRH-antagonist cycles with an agonist trigger
Authors: Nahshon C , Skvirsky S , Assaf W , Kugelman N , Lahav-Baratz S , Blais I , Koifman M , Younes G , Oron G 
Published: June 2022

Abstract

Study question
Are LH levels on day of trigger correlated with the number of oocytes retrieved and oocyte maturation rate in GnRH-antagonist cycles with an agonist trigger?

Summary answer
Low LH levels on the day of trigger were associated with a lower oocyte retrieval rate yet no correlation with oocyte maturation rates was found.

What is known already
The concept that a bolus of gonadotrophin-releasing hormone agonist (GnRHa) can replace human chorionic gonadotrophin (HCG) as a trigger of final oocyte maturation was introduced several years ago. GnRHa trigger offers important advantages including the prevention of ovarian hyperstimulation syndrome (OHSS) with the elicitation of an endogenous LH and FSH surge. Therefore, we sought to evaluate whether LH levels on the day of the trigger are associated with the efficacy of the trigger in eliciting endogenous LH surge and thereby influencing oocyte retrieval and oocyte maturation rates.

Study design, size, duration
This retrospective single center study included all GnRH antagonist cycles triggered with GnRHa trigger (Decapeptyl 0.2mg) performed at our IVF unit between July 2013 and December 2020. We studied the association between LH levels on the day of trigger and the number of oocytes retrieved. Additionally, we studied the effect of LH levels on oocyte maturation rates.

Participants/materials, setting, methods
All GnRH antagonist cycles triggered with GnRHa trigger were included. Data was acquired through individual review of medical records. Linear regression was used to study the correlation between LH levels and oocyte retrieval and maturation rates. Moreover, LH levels on day of trigger were divided ≤1 IU/L and &gt; 1 IU/L to further investigate this correlation. The ratio between Basal LH and LH on day of trigger was investigated as well.

Main results and the role of chance
There were 211 GnRH antagonist cycles triggered with GnRH agonist trigger during the study period. The mean age of patients in the study group was 30.1±4.8 y/o, mean basal LH levels were - 6.8±3.4 IU/L, mean Basal FSH levels were - 6.7±1.9IU/L and the mean total dose of gonadotropin administered was 1633.4±680.6 Units. The mean E2 levels were 11,444±7018.5 pmol/L and the mean number of oocytes retrieved was 19.8±10.2. A correlation was found between lower LH levels on the day of trigger and the number of oocytes retrieved (p &lt; 0.001). No correlation was found between LH levels on the day of trigger and oocyte maturation rates (p = 0.82). The ratio between Basal LH and LH on day of trigger was not found to be a significant factor influencing either the number of oocytes retrieved or oocyte maturation rate. When dividing the group by LH on day of trigger to below and above 1, a borderline difference was found relating to oocyte retrieval rate between the two groups (p = 0.06).

Limitations, reasons for caution
The retrospective nature of the study is the main limitation. Patients receiving GnRHa trigger are mainly a selective population of either high responders or patients for fertility preservation stimulated to retrieve many oocytes, therefore findings may not be applicable to normal or poor responders.

Wider implications of the findings
Low LH levels on day of trigger were found associated with lower oocyte retrieval rates. GnRHa has become an alternative to standard hCG triggering in certain situations. These are preliminary findings of an ongoing study designed to investigate the efficacy of GnRHa trigger according to cycle parameters including LH levels.

Trial registration number
not applicable