title: [Arterial-adaptive dilatation and Doppler velocimetry in normal fetuses with a single umbilical artery].
abstract: OBJECTIVE
  In this study we examined the arterial-adaptive dilatation and Doppler velocimetry, especially RI values, in normal fetuses with a single umbilical artery (SUA).
  
  
  METHODS
  We studied 195 fetuses from 18 to 39 weeks of gestational age with a prenatally identified SUA retrospectively. They were enrolled in this study if the following information applied: > 18 weeks of gestational age, no structural or chromosomal abnormalities, and histopathological confirmation of SUA. Sonographic examination included evaluation of the umbilical artery resistance and the cross-sectional area of the umbilical cord, and its vessels were measured in all cases. Small for gestational age (SGA) was diagnosed when the birth weight was below the 10th percentile for gestational age. Fetuses with intrauterine growth restriction were defined as those with biometric data below the 5th percentile.
  
  
  RESULTS
  There were 119 cases of prenatally identified SUA which met the inclusion criteria. RI values were below the 10th percentile in 33/119 (27.33) and below the 50th percentile in 73/119 (61.33). RI values below the 10th percentile were significantly more likely to be in the normal collective than in the growth restricted collective [31/87 (35.63%) vs. 2/32 (6.25%); p = 0.001]. Even more significant differences became apparent when comparing the RI values below the 50th percentile of both groups. An umbilical artery diameter over the 90th percentile was found in 49 (41.9%) of cases and was significantly more likely to be present in normal growing fetuses than in the growth restricted group.
  
  
  CONCLUSIONS
  Normal fetuses with SUA are at higher risk to be born as SGA. With our study results we can confirm the hypothesis that Doppler flow measurements and arterial diameter in SUA are different from those found in normal fetal umbilical arteries. RI values over the 50th percentile or a cross-sectional area of the artery below 95th percentile after 26th week of gestation significantly increases the risk of SGA.
authors.affiliation: Klinik und Polikliniken für Frauenheilkunde, Universitätsspital Bern und Universität Bern, Schweiz.
authors.forename: G
authors.initials: G
authors.lastname: Suess
authors.forename: L
authors.initials: L
authors.lastname: Raio
authors.forename: A
authors.initials: A
authors.lastname: Kuhn
authors.forename: E
authors.initials: E
authors.lastname: Di Naro
authors.forename: D
authors.initials: D
authors.lastname: Surbek
mesh_terms: D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging / Q000453:epidemiology; D005323:Fetal Monitoring; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D018579:Patient Selection; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012189:Retrospective Studies; D018570:Risk Assessment; D018608:Ultrasonography, Doppler / Q000379:methods; D014469:Umbilical Arteries / Q000000981:diagnostic imaging* / Q000502:physiology; D014664:Vasodilation