Intraobserver reproducibility of Doppler measurements of uterine artery blood flow velocity in premenopausal women

Objective To determine the intraobserver repeatability, of Doppler measurem ents of uterine artery blood flow velocity and the contribution of various factors to within-subject variance. Design Seventeen healthy premenopausal women underwent vaginal Doppler ultr asound examination of the uterine artery, by the same observer. Three measu rements were taken at Each of three sites: 1) the currently recommended sam pling site; 2) the ascending branch of the uterine artery at a level betwee n the lower and middle third of the corpus uteri; 3) 1.5 cm lateral to the recommended sampling site. Three measurements were taken at each site. For each measurement, three uniform consecutive cardiac cycles were analyzed. P eak systolic velocity, time-averaged maximum velocity, and pulsatility, inn er were calculated. Each Doppler shift spectrum was analyzed twice. Thus, f or each woman, 18 measurement results per sampling site were obtained. Anal ysis of variance was used. Results The effect of sampling site on measurements of peak systolic veloci ty and time-averaged maximum velocity was non-significant, but pulsatility index values obtained at the distal sampling site were slightly higher than those obtained at the other sites (P = 0.01). Repetition accounted for mos t of the within-subject variance. Averaging the results of the three repeat measurements yielded increased intraclass correlation coefficients: 0.79-0 .89 for peak systolic velocity, 0.80-0.92 for time-averaged maximum velocit y and 0.86-0.93 for pulsatility index. Conclusion As the effect of repetition on the results of Doppler measuremen ts of uterine artery blood flow velocity is large, the average of several r epeat measurements should be used to enhance measurement reproducibility. H owever, it is not worth doing move than one analysis of a Doppler shift spe ctrum, and it is not worth analyzing more than one cardiac cycle per spectr um.