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Reference ranges for serial measurements of blood velocity and pulsatility index at the intra‐abdominal portion, and fetal and placental ends of the umbilical artery
Author(s) -
Acharya G.,
Wilsgaard T.,
Berntsen G. K. R.,
Maltau J. M.,
Kiserud T.
Publication year - 2005
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.1902
Subject(s) - medicine , umbilical artery , fetus , gestational age , gestation , blood flow , hemodynamics , pregnancy , obstetrics , fetal circulation , diastole , preeclampsia , cardiology , placenta , blood pressure , genetics , biology
Objective To construct reference ranges for serial measurements of umbilical artery (UA) blood flow velocity and pulsatility index (PI) at standardized insonation sites during the second half of pregnancy. Methods This was a prospective longitudinal study of the umbilical circulation. UA blood flow velocities were measured at the intra‐abdominal portion, fetal end and placental end at 4‐weekly intervals at 19–42 weeks of gestation in 130 low‐risk singleton pregnancies. A total of 513 observations were used to construct the reference ranges using regression statistics and multilevel modeling. Results UA blood velocities and PI were higher at the intra‐abdominal portion and fetal end than at the placental end. The gestational age‐related increase of end‐diastolic velocity was greater than the corresponding increase of the peak systolic velocity at all locations. The mean differences (delta values) of UA blood velocities between the fetal and placental ends increased and that of PI decreased with advancing gestational age. Conclusion UA Doppler parameters vary significantly at different locations. We have established new reference ranges for the UA velocities and PI at standardized locations based on longitudinal observations, which should be useful for the surveillance of fetuses with repeated observations. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.