Uterine Radial Artery Resistance Index Predicts Reproductive Outcome in Women with Recurrent Pregnancy Losses and Thrombophilia.

Uterine radial artery resistance index (URa-RI) by Doppler ultrasound may reflect the changes in the uteroplacental circulation and be associated with adverse events in early pregnancy. Recurrent pregnancy losses (RPL) are associated with thrombophilia, and anticoagulation treatment with low molecular weight heparin improves pregnancy outcome in women with RPL and thrombophilia. A retrospective cohort study was conducted in 139 pregnant women with 3 or more RPL and thrombophilia. The relationship between pregnancy outcome and dynamic changes of URa-RI was analyzed in 116 women who delivered a liveborn infant and 23 who miscarried the index pregnancy. Patients were on preconception low molecular weight heparin, low-dose aspirin (81mg per day), and prednisone treatment. URa-RI was measured during periovulation time, at the time of positive pregnancy test, and then repeated every two weeks until 32-week gestation or the time of miscarriage. The URa-RI at 8-week gestation was significantly higher in women who miscarried the index pregnancy than those who delivered alive born infant (0.51±0.08 vs. 0.42±0.03, P<0.001). Receiver operating characteristic curve analysis demonstrated that URa-RI of 8 wk gestation effectively distinguished women who miscarried from those who had a live birth with an area under the curve of 82.6% (95% CI 69.01-97.17). After adjusting for covariates including age, BMI, and number of miscarriages, multiple logistic regression models showed that each 0.1 unit increase of URa-RI of 8 wk gestation was associated with 18.70-point increase in the risk of miscarriage (OR19.70, 95%CI 4.26-91.1, P<0.001), and women with an URa-RI≥0.45 had an OR of 49.48 (95% CI 8.01-307.95; P<0.001) for miscarriage compared to those who had URa-RI<0.45. In women with RPL and inherited thrombophilia, increased URa-RI at 8-week gestation was associated with spontaneous abortion independent of other risk factors while they were on anticoagulation treatment.