Abstract: Objective: To explore the correct test ways of the ductus venosus(DV) blood flow spectrum of the normal fetal and the rule of changes of the normal fetal DV blood flow spectrum along with gestational week,and to establish the reference ranges of the parameters of blood flow. Methods: A total of 320 cases of single fetal pregnant women within 11-40 weeks were selected as the objects.Using color doppler echocardiography,the ventricular systolic peak velocity(SV),atrial systolic trough(aV),pulse index(PI) and resistance index(RI) were measured,and the ratio of ventricular systolic peak velocity trough ratio(S/a) from ultrasonic standard section was calculated.All of these were analysed statistically. Results: The doppler spectrum of normal fetal DV blood flow showed the same three-phase waves,SV was increased with the increase of gestational age(F=27.00,P=0.000),and aV was elevated with the increase of gestational age(F=389.81,P=0.000),while PI(F=65.41,P=0.000),RI(F=58.82,P=0.000) and S/a ratio(F=47.79,P=0.000) were decreased with the increase of gestational age. Conclusion: The performance of color Doppler flow imaging of normal fetal DV showed that the blood flow peak speed is increased along with the increase of gestational age and PI,RI and S/a are reduced with the increase of gestational age,and RI has the largest decline,which has important diagnosis value.

Key words: change rule, ductus venosus, flow spectrum, fetal