title: Does the level of amniotic fluid have an effect on the accuracy of sonographic estimated fetal weight at term?
abstract: OBJECTIVE
  Controversy exists concerning the impact of amniotic fluid index (AFI) on the accuracy of sonographic estimation of fetal weight (EFW). Thus, we aimed to evaluate whether differences in AFI has an influence on the accuracy of sonographic EFW.
  
  
  METHODS
  All term, singleton pregnancies which underwent a sonographic EFW and measurement of AFI within a week from delivery were included. Cases were stratified into three categories according to AFI: (1) Normal AFI (51-249 mm), (2) Oligohydramnios (AFI ≤ 50 mm) and (3) Polyhydramnios (AFI ≥ 250 mm). Inaccurate EFW was defined if there was more than 15% difference between sonographic EFW and actual birthweight.
  
  
  RESULTS
  Overall, 1746 pregnancies were identified (1096 with normal AFI, 455 with oligohydramnios and 195 with polyhydramnios). Mean AFI was 115.8 ± 60 mm, 28.1 ± 13 mm and 293 ± 35 mm, p < 0.001, and mean sonographic EFW was 3182.5 ± 573 g, 3118.8 ± 517 g and 3713.2 ± 461 g, p < 0.001, respectively. Demographic data and gestational age at delivery were similar. Mean birthweight was 3221.7 ± 535 g, 3132.5 ± 505 g and 3654.1 ± 480 g, p < 0.001, respectively. The rate of inaccurate EFW was similar between the groups (8.4%, 8.7% and 9.7%, p = 0.19, respectively). On multivariate analysis, AFI was not associated with EFW inaccuracy (OR 1.01, 95% C.I 0.67-1.54, p = 0.93).
  
  
  CONCLUSIONS
  AFI has limited impact on the percentage of errors in sonographic fetal weight estimation a week prior delivery.
authors.affiliation: Department of Obstetrics and Gynecology, Helen Schneider Hospital for Women, Rabin Medical Center , Petach Tikva , Israel and.
authors.forename: Eran
authors.initials: E
authors.lastname: Ashwal
authors.forename: Liran
authors.initials: L
authors.lastname: Hiersch
authors.forename: Nir
authors.initials: N
authors.lastname: Melamed
authors.forename: Ron
authors.initials: R
authors.lastname: Bardin
authors.forename: Arnon
authors.initials: A
authors.lastname: Wiznitzer
authors.forename: Yariv
authors.initials: Y
authors.lastname: Yogev
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000000981:diagnostic imaging* / Q000502:physiology*; D001724:Birth Weight; D005260:Female; D020567:Fetal Weight; D006801:Humans; D007231:Infant, Newborn; D016104:Oligohydramnios / Q000000981:diagnostic imaging / Q000453:epidemiology; D006831:Polyhydramnios / Q000000981:diagnostic imaging / Q000453:epidemiology; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D015203:Reproducibility of Results; D012189:Retrospective Studies; D047929:Term Birth; D016216:Ultrasonography, Prenatal / Q000592:standards / Q000706:statistics & numerical data
keywords: Amniotic fluid index; fetal weight; oligohydramnios; polyhydramnios; ultrasound