P-579 The effect of serum progesterone level on ET Day and the efficacy of rescue progesterone treatment on ongoing pregnancy rates with artificial FET cycles
Authors: Ozcan P , Çetin Ç , Ökten B , Tanoğlu F.B , İşlek H.S , Pasin Ö , Fıçıcıoğlu C 
Published: June 2022

Abstract

Study question
To evaluate serum progesteron level on ET day during FET cycles with a vaginal progesterone tablet plus weekly twice IM progesteron; to determine the efficacy of resque sc progesteron treatment

Summary answer
Resque daily sc progesterone treatment can improve PRs. The measurement of progesterone on ET day may create a chance to resque treatment on ET day.

What is known already
Successful implantation requires a suitable decidualized endometrium combined with a good quality embryo. The secretory phase of endometrium induced by progesterone is one of the most crucial steps for a proper implantation process and continuation of pregnancy. Recently, with improved cryopreservation techniques, Frozen–thawed embryo transfer (FET) has commonly used all over the world due to several reasons. Programmed- artificial FET cycles are different in terms of luteal phase because endogenous corpus luteum is absent. Therefore, programmed- artificial FET require hormone replacement treatment including estradiol and progesterone.

Study design, size, duration
We prospectively designed this multi-centric cohort study (NCT04769401) and carried out this study at IVF center of Acibadem Health Group and Bezmialem University Hospital and between February 2021 and September 2021. A total of 238 programmed-artificial FETs, carried out by two expert gynecologists (P.O. and C.F.) were evaluated.

Participants/materials, setting, methods
Estrofem was orally started. At 14 days of estrofem, Progesterone was started (100 mg vaginal progesterone tablet two times per day and 250 mg IM hydroxyprogesterone caproate weekly twice). Serum progesterone level were analysed at ET day and two days later. 25 mg/d of SC progesterone daily was given to patients with low serum progesterone levels at ET day and ET was performed on the same day.

Main results and the role of chance
Of all transfers, 77.2% (127/222) resulted in CP. Although there was no statistically significant difference with regard to CPR, OPR and miscarriage between groups (55,4% vs 61,5%, P = 0.4; 78,2% vs 72,5%, P = 0.5; 21,8/% vs 27,5%, P = 0.5; respectively progesterone levels on ET day ≥10 ng/ml and &lt;10 ng/ml) ongoing PR was higher and misscarriage was lower in patients with serum progesterone levels on ET day ≥10 ng/ml. 84% (n = 54) of patients with low serum progesterone level on ET day reached adequate progesterone level with resque sc progesterone treatment (≥10 ng/ ml). 90% (36/40) of PRs in patient with serum progesterone levels &lt;10 ng/ml on ET day was in patient with reaching adequate serum progesterone level with resque daily sc progesterone treatment. Age, number of previous IVF attempts and the embryo flash position at 1 minutes after ET were significantly lower in patients who conceived (p = 0.002, p = 0.016, p = 0.025, respectively).

Limitations, reasons for caution
The limitation of our study is not to present live birth rate.

Wider implications of the findings
The study demonstrated that adequate progesterone level on ET day is reached in 70,7% with the combination of vaginal progesterone tablet plus 250 mg of IM hydroxyprogesterone caproate. Patients with low progesterone level can achieve similar PR when adequate progesterone level was reached with resque sc progesterone treatment.

Trial registration number
NCT04769401