Background and Objective: Infertility is a major global health challenge, and inadequate endometrial receptivity is recognized as an important cause of implantation failure in assisted reproductive treatment. Noninvasive assessment of endometrial readiness is important for optimizing the timing of embryo transfer in IVF cycles. This study aimed to evaluate the role of color Doppler ultrasonography in predicting successful embryo transfer based on endometrial receptivity in infertile women.
Methods: This prospective cohort study included 85 women with unexplained infertility undergoing IVF-ET at Shahid Sayyad Shirazi Teaching Hospital in Gorgan, Iran. Transvaginal Doppler ultrasonography was performed before embryo transfer to measure endometrial thickness and morphology, myometrial echogenicity, uterine artery flow indices, and endometrial and myometrial vascularity. The uterine scoring system for reproduction (USSR) parameters evaluated included endometrial thickness, endometrial morphology, endometrial and myometrial blood flow, uterine artery Doppler index, and myometrial contractions. Endometrial vascularity was divided into four zones according to the Applebaum classification, with zone 3 indicating vascular penetration into the inner hypoechoic layer of the endometrium. Pregnancy outcomes were compared between women with successful and unsuccessful implantation.
Results: Pregnancy occurred in 32.9% of the women. Endometrial thickness and the extent of zone 3 vascularity were significantly associated with successful pregnancy. The highest implantation rate (51%) was observed among women with an endometrial thickness of 7-9 mm (P<0.05). Women with no blood flow in zone 3 had a significantly higher pregnancy rate than those with low flow (P<0.05). Other variables, including endometrial morphology, uterine artery pulsatility index, myometrial contractions, and the USSR scoring system, showed no significant predictive value.
Conclusion: Certain Doppler ultrasonographic indices, particularly optimal endometrial thickness and vascular patterns, may help identify cycles with greater potential for successful implantation.