Preliminary study of fetal ductus venosus flow waveforms at 10-19 weeks gestation

Objective To discuss the method of detecting fetal ductus venosus flow waveforms by trans-abdominal color Doppler ultrasound and to establish reference value ranges of resistance index(RI),pulsatility index(PI) and the ratio of the peak velocity during ventricular systole to lowest velocity during atrial systole(S/A) for fetuses at 10-19 weeks of gestation.Meanwhile,to discuss the occurrence rate of zero or reversed flow during atrial contraction(RA) in normal fetuses of 10-14 weeks of gestation.Methods(Without correcting) insonation angle,ductus venosus flow waveforms were obtained randomly from 111 singleton pregnancies at 10-19 weeks of gestation.Fetuses with chromosome malformation,severe heart malformation or growth retardation were excluded.Reference values of RI,PI and S/A were constructed by regression analysis.Results The values for RI,PI and S/A decreased with increasing gestational age.The 95% reference values of RI,PI and S/A were(0.34)-(0.90),(0.21)-(1.32) and(1.23)-(6.65) respectively.Zero or RA wave was not discovered in this study.Conclusions Assessment of ductus venosus blood flow waveforms during 10-19 weeks of gestation is feasible through trans-abdominal color Doppler.Reference value ranges of RI,PI and S/A were established in this study,and it may be utilized in further studies dealing with the role of ductus venosus blood flow in fetuses with chromosome malformation,severe heart malformation.Whether or not the physiological zero or RA wave exists in the ductus venosus of fetuses at 10-14 weeks of gestation need further investigation.