Fetal tricuspid valve Doppler at 11-13 weeks and 6 days: reference values and reproducibility

To determine normal blood flow velocities across the fetal tricuspid valve (TV) at 11-13 weeks and 6 days of gestation and to examine the reproducibility of these measurements.

A prospective study involving 166 normal singleton pregnancies examined at 11-13 weeks and 6 days was carried out. Descriptive analysis of E- and A-waves' maximum velocities, E/A ratio, duration of the cardiac cycle (C) and diastole (D) and D/C ratio were calculated. Intraobserver and interobserver agreement analysis was performed in a subgroup of 12 cases.

Average ( +/- SD) flow velocities were: E-wave, 25.0 ( +/- 4.6) cm/s; A-wave, 42.9 ( +/- 5.9) cm/s; E/A, 0.58 ( +/- 0.07); cardiac cycle, 390 ( +/- 21.1) ms; diastole, 147 ( +/- 18) ms and D/C, 0.38 ( +/- 0.04). Significant correlation was observed between all parameters (except A-wave) and gestational age but not with nuchal translucency (NT). Intraclass correlation coefficients (interobserver, intraobsever examiner 1 and intraobserver examiner 2) were: E-wave, 0.53, 0.53 and 0.64; A-wave, 0.45, 0.46 and 0.49; cardiac cycle, 0.70, 0.79 and 0.84 and diastole, 0.63, 0.85 and 0.82, respectively.

The present study establishes normal Doppler parameters for blood flow across the TV at 11-13 weeks and 6 days and demonstrates that these parameters do not correlate with NT measurement and have good/moderate reproducibility.