title: Standards for the quantification of serial changes in Doppler resistance indices from the umbilical arteries.
abstract: Two-hundred- and-seventy-four low-risk pregnancies underwent serial ultrasound examinations in order to determine the mean and standard deviation of the change in umbilical artery resistance indices with advancing gestation. There is an almost constant rate of reduction in the A/B ratio and the Pulsatility index over time from 28 weeks gestation until term. By calculating the standard deviation score of such changes, these reference ranges allow the change in the A/B ratio and Pulsatility index to be quantified. Such appropriately derived standards permits the further investigation of the evolution of abnormalities of feto-placental perfusion with regards to perinatal outcome.
authors.affiliation: Department of Obstetrics and Gynaecology, Ninewells Hospital and Medical School, Dundee, Scotland.
authors.forename: P
authors.initials: P
authors.lastname: Owen
authors.forename: S
authors.initials: S
authors.lastname: Ogston
mesh_terms: D001724:Birth Weight; D005260:Female; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011673:Pulsatile Flow; D012016:Reference Values; D014465:Ultrasonics; D014469:Umbilical Arteries / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology*