F25Changes in the endometrium between the day of oocyte retrieval and embryo transfer. Does it matter?

Background Multiple studies have confirmed a lower implantation and pregnancy rates in women who exhibit a homogenous pattern of the endometrium compared to a triple‐line pattern on the day of hCG administration. However, there are no studies comparing the pattern of endometrium and its vascularization on the days of oocyte retrieval and embryo transfer. Methods We prospectively evaluated the endometrium in 97 women undergoing 116 IVF‐ET cycles. Endometrial thickness and pattern, endometrial vascularization and blood flow waveforms in subendometrial vessels and uterine arteries were registered on the days of oocyte retrieval and embryo transfer. Results There was no difference in age, basal FSH, number of oocytes, number of embryos transferred and endometrial thickness between pregnant and nonpregnant patients, or between patients with homogenous endometrium and those with triple‐line pattern of the endometrium. The ongoing implantation rate was 11% having homogenous endometrium and 23% having triple‐line pattern of the endometrium on the day of oocyte retrieval. By the day of embryo transfer 89% of endometrium seemed to be homogeneously echogenic. All pregnancies occurred in the patients who had a homogenous endometrium on the day of embryo transfer. Conclusion Endometrial pattern, rather than endometrial thickness on the day of oocyte retrieval and its changes towards the day of embryo transfer appear to be important prognostic factors of endometrial receptivity.