Objective To explore the feasibility and clinical significance of using the ultrasound multimodal scoring method to evaluate endometrial receptivity to predict the pregnancy success rate of frozen-thawed embryo transfer(FET).

Methods A total of 87 infertile patients who visited the First Affiliated Hospital of Bengbu Medical University from December 2023 to July 2024 and underwent FET were selected as the research subjects, and were divided into the pregnancy success group(n=41) and pregnancy failure group(n=46) according to the clinical pregnancy outcome. The differences of the general data, ultrasound indicators on endometrial transformation day and multimodal ultrasound score between two groups were compared. The receiver operating characteristic(ROC) curve was used to analyze the diagnostic value of each parameter for the clinical pregnancy outcome of FET.

Results The differences in the endometrial volume, endometrial morphological classification, endometrial blood flow classification, endometrial vascularization index (Ⅵ) and vascularization blood flow index(VFI) under three-dimensional energy Doppler mode were statistically significant between two groups(P < 0.05). The difference in the endometrial Ⅵ and VFI and ultrasound multimodal score under three-dimensional energy-ultra-micro angiography were statistically significant between two groups(P < 0.01). The results of binary logistic regression showed that the endometrial receptivity ultrasound multimodal score was an independent influencing factor for the clinical pregnancy outcome of FET patients(OR=3.726, 95%CI=1.855-7.485, P < 0.01). The ROC curve showed that the area under the curve(AUC) of the multimodal score of endometrial receptivity ultrasound was the highest.

Conclusions In the transvaginal ultrasound examination of endometrial transformation in FET patients, the endometrial Ⅵ and VFI, endometrial volume, endometrial morphological classification, endometrial blood flow classification under three-dimensional energy Doppler and three-dimensional energy-ultra-micro blood flow imaging modes, as well as the proposed ultrasound multimodal scoring method, have certain diagnostic value for predicting clinical pregnancy outcomes.