Intraobserver variability of pulsatility index measurements in three fetal vessels in the first trimester

Abstract

Purpose The intraobserver repeatability of pulsatility index measurements in 3 fetal vessels in the early weeks of gestation was evaluated. Methods The pulsatility index was calculated from the flow velocity waveforms from 3 fetal vessels in a series of 58 uneventful, low-risk, singleton first-trimester pregnancies using transvaginal color Doppler sonography. The intraobserver repeatability was expressed as the intraclass correlation coefficient. Mean menstrual age at the time of the examination was 10.3 weeks (range, 7.6–13). Results Flow velocity waveforms from the umbilical artery, abdominal aorta, and middle cerebral artery were obtained in 100% (58/58), 98.3% (57/58), and 100% (34/34) of cases, respectively. The intraclass correlation coefficients for these vessels were 0.89, 0.79, and 0.93, respectively. Conclusions The intraobserver repeatability was acceptable for all the vessels studied. © 1997 John Wiley & Sons, Inc. J Clin Ultrasound 25: 366–371, 1997.