Objective: This study aimed to determine if using a dedicated embryo transfer medium improves clinical outcomes, compared with a versatile embryo culture medium used for transfer, independent of embryo culture medium.

Study Question: Does use of a dedicated embryo transfer medium improve clinical outcomes compared with a versatile embryo culture medium used for transfer, independent of embryo culture medium?

Summary Answer: Pregnancy rates did not differ between dedicated and versatile embryo transfer media, regardless of the embryo culture medium used.

What is known already: Whether a dedicated embryo transfer medium is required to optimize frozen embryo transfer outcomes remains debated. Published data are conflicting, with some studies suggesting improved pregnancy rates compared with versatile embryo culture media, while others demonstrate no clinical advantage. Further evaluation in controlled laboratory settings is warranted.

Study design, size, duration: This retrospective study evaluated all euploid frozen embryo transfer (FET) cycles performed between 2023 and 2025. Four conditions were assessed using two embryo culture media (ECM) and two embryo transfer media (ETM), while vitrification and warming protocols were identical across all groups. A total of 593 FET cycles were included for pregnancy rate analysis.

Participants/Materials, Settings, methods: Euploid autologous FET cycles were analyzed in a private IVF center. Embryos were cultured in either CSCM-NXC or GxTL and transferred using either CSCM-NXC as a versatile transfer medium or EmbryoGlue as a dedicated transfer medium. Blastocyst vitrification and warming were performed using standard protocols with Irvine Scientific kits. Blastocyst recovery procedures, embryo transfer catheters, physician practices, and embryology staffing remained unchanged across all conditions.

Main results and the role of chance: Pregnancy rates were similar across all four conditions (63.2%, 66.5%, 67.2%, and 62.5%; respectively, p=0.828). When analyzed by embryo culture medium, pregnancy rates were comparable between CSCM-NXC (64.1%) and GxTL (64.5%), irrespective of transfer medium (p=0.904). Similarly, no difference was observed when comparing embryo transfer media alone, with CSCM-NXC and EmbryoGlue yielding pregnancy rates of 65.1% and 62.8%, respectively (p=0.561). These findings indicate no clinical advantage of a dedicated embryo transfer medium over a versatile culture medium for embryo transfer in this setting.

Limitations, reasons for caution: A larger sample size would enable a higher statistical power.

Wider implications of the findings: The ability to use an embryo transfer medium that is also widely available and usable for a wide range of laboratory processes has the potential to improve laboratory ordering, storage and workflow as well as reducing potential procedural errors.