Comparative Study of Abdominal Versus Transvaginal Ultrasound for Uterine Artery Doppler Velocimetry at 11 to 13 Weeks

Objectives To compare the first‐trimester uterine artery pulsatility index (PI) measured by abdominal and transvaginal ultrasound (US). Methods We performed a prospective study of singleton pregnant women recruited at 11 to 13 weeks' gestation. The mean uterine artery PI was obtained by abdominal followed by transvaginal US. The mean of the left and right uterine artery PIs was used, and differences between approaches were computed. The intraclass correlation coefficient and a Bland‐Altman plot were used to compare the two approaches. Results Data were available for 940 participants, including 928 (99%) with uterine artery PIs obtained on both uterine sides. The mean uterine artery PI decreased with gestational age in both approaches (P