Contraction-based uterine artery Doppler velocimetry: novel approach for prediction of preterm birth in women with threatened preterm labor.

ABSTRACT

OBJECTIVE: To evaluate whether uterine artery (UtA) Doppler velocimetry during peak uterine contraction is a useful marker for the prediction of preterm delivery. METHODS: In this prospective cohort study, 172 patients admitted with preterm (24-35 weeks' gestation) uterine contractions were evaluated by UtA Doppler velocimetry during peak uterine contraction and by common obstetric measurements including cervical length. For UtA Doppler velocimetry, flow-velocity waveforms during peak uterine contraction (determined visually on tocodynamometry) were recorded during three consecutive heart cycles, and the mean UtA pulsatility index (UtA-PI) was calculated. RESULTS: UtA-PI during the peak of contractions was significantly higher in patients who delivered within 7 days than in those who did not (P < 0.001). On receiver-operating characteristics curve analysis of UtA-PI on contraction, the areas under the curve for prediction of delivery within 48 h, 7 days or 14 days, ≤ 35 weeks and ≤ 37 weeks were 0.92, 0.88, 0.81, 0.83 and 0.74, respectively. Multiple regression analysis identified UtA-PI on contraction (P < 0.001) and cervical length (P < 0.001) as predictors of admission-to-delivery interval. The corresponding adjusted odds ratios for delivery within 7 days were 16.5 (95% CI, 5.7-47.2) for UtA-PI on contraction ≥ 1.32, and 14.7 (95% CI, 5.2-41.8) for cervical length ≤ 28 mm. CONCLUSION: Use of UtA Doppler velocimetry during peak uterine contraction for patients exhibiting symptoms of preterm labor might be effective for the identification of pregnant women at risk of preterm delivery. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.