title: Umbilical artery blood velocity waveform analysis in predicting the small-for-dates fetus.
abstract: Doppler umbilical artery blood velocity waveforms were recorded longitudinally in 78 randomly selected pregnancies. The waveform maximal (A) to minimal (B) Doppler shift frequency ratios were determined to provide a semi-quantitative measure of impedance to blood flow in the fetoplacental circulation. Fifty-eight of these pregnancies and their outcomes were normal. The A/B ratios from this normal group were used to derive a normal range of this index throughout the second half of pregnancy. A further 45 pregnancies, also randomly selected, were studied once within 2 weeks of delivery. Using those measurements, plus those from the longitudinal groups sampled within 2 weeks of delivery, the predictive values of the A/B ratio in detecting the small for gestational age fetus have been derived. The sensitivity of the umbilical artery A/B ratio in predicting a small for gestational age infant within 2 weeks of delivery was 58% with a specificity of 94%. The positive test predictive value was 69% with a negative test predictive value of 90%. These predictive values are lower than those previously published, probably because high-risk pregnancies were over-represented in earlier studies. Waveform analysis within 2 weeks of delivery did, however, appear to identify fetuses destined to develop a range of perinatal problems. Large prospective studies are needed before the predictive value of Doppler waveform analysis is clarified.
authors.affiliation: Department of Midwifery, University of Glasgow, Scotland.
authors.forename: S J
authors.initials: SJ
authors.lastname: Hastie
authors.forename: C A
authors.initials: CA
authors.lastname: Howie
authors.forename: M J
authors.initials: MJ
authors.lastname: Whittle
authors.forename: J E
authors.initials: JE
authors.lastname: Flemming
authors.forename: P C
authors.initials: PC
authors.lastname: Rubin
mesh_terms: D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age / Q000502:physiology*; D008137:Longitudinal Studies; D011237:Predictive Value of Tests; D011247:Pregnancy; D012016:Reference Values; D014463:Ultrasonography; D014469:Umbilical Arteries / Q000502:physiology*