# Long-term reproducibility and clinical utility of endometrial receptivity analysis in guiding personalized embryo transfer: case reports of sustained success over four years post-endometrial biopsy

## TL;DR

This paper shows that endometrial receptivity analysis results can remain useful for guiding embryo transfers up to four years later, helping patients with a history of implantation failure achieve successful pregnancies.

## Contribution

The study demonstrates the long-term reproducibility of ERA results in guiding personalized embryo transfer without repeat biopsies.

## Key findings

- Two patients achieved successful pregnancies using ERA results from over four years prior.
- No repeat endometrial biopsy was needed for subsequent embryo transfers.
- The results suggest initial ERA findings may remain valid for future embryo transfers.

## Abstract

To demonstrate the long-term stability and clinical utility of endometrial receptivity analysis (ERA) test in guiding personalized embryo transfer (pET) for patients with a history of recurrent implantation failure (RIF), even after an intervening live birth.

Two RIF patients, who had previously achieved a live birth via ERA-guided pET, sought a second pregnancy. For their subsequent personalized frozen-thawed embryo transfer cycles, progesterone administration timing was adjusted based on the receptive window identified by a single ERA test conducted more than four years earlier. No repeat endometrial biopsy was performed in either patient.

Both patients underwent pET following the recommendations derived from their original ERA results. Both achieved successful clinical pregnancies and subsequently delivered healthy live infants.

These findings preliminarily suggest that repeat endometrial biopsy might not be necessary for subsequent pET in RIF patients with similar clinical backgrounds. However, given the small sample size of this case series, further large prospective studies are still needed to confirm the long-term utility of initial ERA results and the appropriateness of omitting repeat biopsies.