730: Doppler velocimetry: A comparison of the intrafetal to extrafetal segments of the umbilical artery(UA) (original) (raw)

Insonation of the UA in the amniotic cavity can be challenging in multiple gestations and can be influenced by the adjacent umbilical arterial and venous pulsations. Our objectives were to provide normal data for Doppler volicimetry in the intrafetal paravesical segment of the UA and compare doppler indices between the intrafetal paravesical segment with the extrafetal amniotic segment of the UA. STUDY DESIGN: Consecutive consenting women between 18 and 42 weeks of gestation were enrolled. Systolic/diastolic (S/D), resistive index (RI), pulsatility index (PI) were determined by sonographers insonating the UA at the two locations. The segment insonated first was alternated. RESULTS: The median, (10th,90th percentile) of the S/D of the intrafetal segment were significantly higher than the extrafetal segment [3.2(2.31,4.85) vs 2.7(2.10,3.93), Pϭ.0001]. The S/Ds in the intrafetal segment were higher than the extrafetal segment in 80.6% of instances. Similar results were obtained for RI and PI. CONCLUSION: Doppler indices are significantly higher in the intrafetal paravesical segment of the UA than in te extrafetal segment. Our normogram might be clinically useful when the extrafetal UA is difficult to insonate or when obtained indices might be unreliable.