INFERIOR VENA-CAVA FLOW VELOCITY WAVE-FORMS RELATIVE TO FETAL BEHAVIORAL STATES AND SAMPLE SITE IN NORMAL TERM PREGNANCY

Reproducibility and behavioural state dependency of flow velocity wave forms from the proximal and distal part of the fetal inferior vena cav a were studied in a total of 27 normal pregnancies at 36-39 weeks of g estation. Within patient coefficients of variation in fetal inferior v ena cava waveform recording were markedly higher for the proximal part compared with the distal part. This is also reflected by lower reliab ility values as a measure of the relative proportion of within patient and between patient variance components. No statistically significant changes in flow velocity values could be detected at proximal and dis tal level of the fetal inferior vena cava relative to fetal behavioura l states. A marked difference in flow velocity values was, however, ob served between the two measuring sites with the highest velocities at proximal level. Since a considerable variation in fetal inferior vena cava flow recording was established, a possible behavioural state rela ted modulation may have been obscured by these waveform variabilities.