Is "Salvage" Addition of Vaginal Estradiol for Suboptimal Endometrial Hypo-Proliferation in FET Cycle Efficient

Introduction: Oral estradiol is commonly used to prepare the endometrium in frozen-thawed embryo transfer (FET) cycles. Addition of vaginal estradiol may increase serum estradiol levels and endometrial thickness in patients who did not respond to oral treatment only. However, little data is known as whether the addition of vaginal estradiol may improve outcome.

Aim: To evaluate the efficacy of adding vaginal Estradiol in patients undergoing FET demonstrating resistant endometrium

Material and Methods: A retrospective analysis of all cases undergoing FET with artificial preparation of the endometrium during the years 2014-2017 at a single academic IVF center (146 cycles). The study group included patients who did not respond to oral estradiol only and were added with vaginal estradiol, the control group included all patient who respond properly.

RESULTS: Of all patients who received oral estrogens prior to FET the hypo-proliferative group consisted 7%. Patient characteristics between the two groups were similar. The maximal estradiol level was 877 pmol/L and 5452pmol/L in the control and study group,respectively. The average endometrial thickness in the study group increased from an average thickness of 5.6 mm to 7.1 mm, however only 63% of them achieved endometrial thickness of >7mm. Clinical pregnancy rate in the study group was 41%, 2/3 of pregnancies appeared in those patients who normalized their serum estradiol levels and endomedrial thickness.

CONCLUSIONS: Salvage vagianl estradiol treatment may be of benefit for patients with endometrial hypo-proliferation in FET cycles, especially in those who normalized their endometrial thickness.