Umbilical artery blood flow characteristics in normal pregnancies

585 pregnant women were investigated with both conventional sonographic examination and color Doppler examination. The cases with intrauterine growth retardation, preeclampsia, twin pregnancies, congenital malformations and diabetes were excluded. The remaining 550 cases (between ages 16 and 40) were investigated in the first trimester and gestational ages were compatible with the last menstrual date. In order to evaluate fetal development, biparietal diameter, femur length, abdominal circumference, and estimated fetal weight were calculated by conventional ultrasonographic method. The application of Doppler ultrasound to the study of fetal umbilical arterial blood flow velocity is a relatively new technique. The failure to obtain useful Doppler signals was about 18-22% with pulse-wave Doppler system. Recently, color Doppler technology solved this problem. We used an ALOKA 680-SSD ultrasonography device and color Doppler ultrasonography technique and recorded umbilical arterial Doppler signals from every case and calculated classical Doppler indices--systolic/diastolic (S/D) ratio, pulsatility index (PI), Pourcelot index or resistive index (RI). Statistical comparisons were made by SPSS program. Correlation coefficient and R2 values between gestational age and other indices were calculated. The aforementioned values were r:-0.79; R2:0.63 0.63; r:-0.71; R2:0.50, r:-0.64; R2:0.41, for S/D, PI, RI, respectively.