DUCTUS VENOSUS FLOW VELOCITY WAVE-FORMS IN RELATION TO FETAL BEHAVIORAL STATES

Objectives To establish the reproducibility of flow velocity waveforms in the human ductus venosus and to assess the influence of fetal behavioural states on these waveforms in normal term fetuses. Design Reproducibility of Doppler waveform recording and analysis was studied in 10 normal pregnancies. The relation between ductus venosus flow velocities and behavioural states was investigated in 19 other term fetuses. Time-averaged, peak systolic, peak diastolic velocity, peak systolic/diastolic ratio and period time were calculated in both cross sectional studies. Setting Outpatient clinic, department of obstetrics (prenatal diagnosis section), Academic Hospital, Rotterdam-Dijkzigt. Subjects Twenty-nine women with normal singleton pregnancies at 36 to 39 weeks of gestation, resulting in uncomplicated births of healthy infants. Results Within-patient coefficients of variation, ductus venosus waveform recordings were approximately 8 to 10% except for the peak systolic/diastolic ratio (4.3%). A decrease of approximately 30% was established for peak systolic, peak diastolic velocity and time-averaged velocity during behavioural state 1F (quiet sleep) as compared with state 2F (active sleep). Conclusions Flow velocity waveform recording in the ductus venosus demonstrates acceptable reproducibility. Fetal behavioural state-dependent changes were observed, suggesting a redistribution of umbilical venous blood through the ductus venosus shunt during the quiet sleep state.