P-341 Endometrial compaction and its impact on reproductive outcome

Abstract Study question Is there a relationship between endometrial compaction and clinical pregnancy rate in frozen embryo transfer (FET) cycles? Summary answer Clinical pregnancy rate (CPR) were similar in both patients that demonstrated endometrial compaction or no compaction in FETs cycles. What is known already There has been increasing interest in the correlation between endometrial compaction and clinical outcomes but there has been conflicting evidence from prior investigations. Study design, size, duration Retrospective Observational data Analysis of (n-350) patients undergoing Embryo Transfer during January 2022 to December 2022 at our clinic. Participants/materials, setting, methods This study was performed at a single, academically affiliated fertility center in which patients who had an FET using programmed/modified natural cycle protocol were included. Endometrial thickness at time start of progesterone(T1)(TVS) & at time of Embryo transfer (T2)(TAS)was measured, and percentage on ET compaction in both HRT cycle and modified natural cycle was studied. The primary outcome (CPR) was based on proportion of compaction (percentage difference in EMT between T1 and T2). Main results and the role of chance Of the 350 participants included, 64%, 38% and10%, of women exhibited >0%, >5% and >10% endometrial compaction, respectively. Endometrial compaction was not predictive of Clinical Pregnancy Rate (CPR) at any of the defined cutoffs .Primary outcomes included CPR (defined as the presence of at least one gestational sac with a fetal pole with cardiac activity on transvaginal ultrasound between 6 and 9 weeks gestation), biochemical pregnancy rate and spontaneous abortion rate. Patients were discharged to their obstetrician when a clinical pregnancy was confirmed between 6 and 9 weeks gestation. Limitations, reasons for caution There was the potential for measurement error in the recorded EMTs. The T2 measurement was performed transabdominally, which may cause potential measurement error, as it is generally accepted that transvaginal measurements of EMT are more accurate, though, any bias is expected to be non-differential Wider implications of the findings Assessing endometrial compaction may lead to unnecessary cycle cancellation. However, further studies are needed to determine if routine screening for endometrial compaction would improve clinical outcomes. Trial registration number not applicable