title: Estimation of fetal weight by ultrasonography after preterm premature rupture of membranes: comparison of different formulas.
abstract: OBJECTIVE
  To compare different ultrasonographic fetal weight estimation formulas in predicting the fetal birth weight of preterm premature rupture of membrane (PPROM) fetuses.
  
  
  METHODS
  Based on the ultrasonographic measurements, the estimated fetal weight (EFW) was calculated according to the published formulas. The comparisons used estimated birth weight (EBW) and observed birth weight (OBW) to calculate the mean absolute percentage error [(EBW-OBW)/OBW×100], mean percentage error [(EBW-OBW)/OBW×100)] and their 95% confidence intervals.
  
  
  RESULTS
  There were 234 PPROM patients in the study period. The mean gestational age at which PPROM occured was 31.2±3.7 weeks and the mean gestational age of delivery was 32.4±3.2 weeks. The mean birth weight was 1892±610 g. The median absolute percentage error for 33 formulas was 11.7%. 87.9% and 21.2% of the formulas yielded inaccurate results when the cut-off values for median absolute percentage error were 10% and 15%, respectively. The Vintzileos' formula was the only method which had less than or equal to 10% absolute percentage error in all age and weight groups.
  
  
  CONCLUSIONS
  For PPROM patients, most of the formulas designed for sonographic fetal weight estimation had acceptable performance. The Vintzileos' method was the only formula having less than 10% absolute percentage error in all gestational age and weight groups; therefore, it may be the preferred method in this cohort. Amniotic fluid index (AFI) before delivery had no impact on the performance of the formulas in terms of mean percentage errors.
authors.forename: Sertac
authors.initials: S
authors.lastname: Esin
authors.forename: Mutlu
authors.initials: M
authors.lastname: Hayran
authors.forename: Yusuf Aytac
authors.initials: YA
authors.lastname: Tohma
authors.forename: Mahmut
authors.initials: M
authors.lastname: Guden
authors.forename: Ismail
authors.initials: I
authors.lastname: Alay
authors.forename: Deniz
authors.initials: D
authors.lastname: Esinler
authors.forename: Serdar
authors.initials: S
authors.lastname: Yalvac
authors.forename: Omer
authors.initials: O
authors.lastname: Kandemir
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D005322:Premature Rupture of Fetal Membranes; D020567:Fetal Weight; D006801:Humans; D011247:Pregnancy; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal; D055815:Young Adult