To evaluate the predictive value of ultrasound uterine artery and endometrial blood flow parameters for pregnancy outcome in patients with unexplained recurrent spontaneous abortion (URSA).

One hundred and twelve patients with URSA were collected retrospectively at Hangzhou Hospital of Traditional Chinese Medicine from January 2020 to December 2021 as the study subjects. According to different pregnancy outcomes, they were divided into a pregnant group (n=55) and a non-pregnant group (n=57). Comparative analysis was conducted on endometrial receptivity indicators (ultrasound uterine artery and endometrial blood flow parameters) of the two groups of patients during pregnancy preparation, using the χ² test or Fisher's exact test or independent sample t-test, and multivariate conditional Logistic regression was used to analyze the relationship between ultrasound parameters and pregnancy outcome.

The pulsatility index of the uterine artery in the pregnant group was significantly lower than that of the non-pregnant group [(2.06±0.42) vs (2.41±0.69), t=4.669, P<0.001]. The endometrial thickness of the pregnant group was significantly higher than that of the non-pregnant group [(8.56±1.42) mm vs (8.19±2.41) mm]. The proportions of patients with endometrial echo type B, endometrial blood flow grade II, and endometrial continuity in the pregnant group were 67.27%, 74.55%, and 90.91%, respectively, which were significantly higher than those of the non-pregnant group (47.37%, 50.88%, and 0, respectively; χ²=12.151, 7.408, and 93.607, respectively; P<0.001 for all). Multivariate conditional Logistic regression analysis showed that elevated uterine artery PI was a high risk factor for pregnancy failure in URSA patients (β=-0.922, odds ratio [OR]=0.924, P=0.004), while endometrial thickness (β=0.514, OR=1.147, P=0.007), endometrial echo type B (β=0.425, OR=1.502, P=0.001), endometrial blood flow grade II (β=0.337, OR=1.655, P=0.002), and endometrial continuity (β=0.437, OR=2.715, P=0.022) were protective factors for successful pregnancy in URSA patients.

The detection of uterine artery blood flow parameters, endometrial morphology, and blood flow parameters by color Doppler ultrasound can accurately evaluate the endometrial receptivity of URSA patients to provide a basis for clinical prediction of successful pregnancy.