Purpose: Embryo transfer is the last and most vital part of the in vitro fertilization treatment process. In recent years embryo transfer protocols have been standardized, but embryo-loading technique did not receive much attention per se. The aim of our study was to compare clinical pregnancy and positive pregnancy test rates between the two different embryo-loading (EL) techniques.
Design: Retrospective cohort study.
Methods: 493 frozen embryo transfer (FET) cycles were included in our retrospective cohort study. From November 2018 until January 2020 “double air bubble” embryo catheter-loading technique was used. Starting from January 2020 until July 2021 lab introduced “medium only” loading-technique. In group A (n=249) loading was done by filling the catheter with 15-20μL of medium and then aspirating 10μL of air followed by 5-10μL of medium containing embryo(s). Adding 10μL of air at the tip of the catheter completed loading. In Group B (n=244) loading was performed by filling the catheter with 15-20μL of medium followed by an additional 5-10μL containing the embryo(s) with no air was aspirated.
Results: No statistical difference was detected between the groups with regard to age, body mass index (BMI), diagnosis, FET cycle characteristics, and quality of embryos transferred (all P>0.05). 493 FETs resulted in 279 positive pregnancy tests and 236 clinical pregnancies. There was no statistical difference between the two groups in clinical pregnancy (47% vs 48.7% P=0.36) and positive pregnancy test rate (55.8% vs 57.3% P= 0.40).
Conclusion: Embryo loading technique did not affect positive pregnancy test or clinical pregnancy rates.