title: Sonographic Weight Estimation in Small-for-Gestational-Age Fetuses.
abstract: OBJECTIVE
  To determine the accuracy of sonographic weight estimation (WE) for small-for-gestational-age (SGA) fetuses, and to further differentiate the evaluation between symmetric and asymmetric SGA fetuses.
  
  
  METHODS
  The accuracy of WE in SGA fetuses (n = 898) was evaluated using 14 sonographic models and was further differentiated between symmetric (n = 750) and asymmetric (n = 148) SGA fetuses. SGA fetuses were considered to be asymmetric with a head circumference to abdominal circumference ratio above the 95th percentile. The accuracy of the different formulas was compared using means of percentage errors (MPE), medians of absolute percentage errors (MAPE), and proportions of estimates within 10 % of actual birth weight.
  
  
  RESULTS
  RESULTS for the subgroup of asymmetric SGA fetuses differed significantly from the subgroup of symmetric SGA fetuses. MPE values were closer to zero with most of the formulas in the asymmetric SGA group. Apart from the Siemer, Shepard, Merz and Warsof equations, all formulas showed an underestimation of fetal weight in asymmetric SGA fetuses. In contrast, in the symmetric SGA group, all of the formulas commonly used for fetuses in a normal weight range showed a systematic overestimation of fetal weight. Overall the best accuracy was achieved by using the Sabbagha equation (MPE 1.7 %; SD 9.0 %; MAPE: 6.0).
  
  
  CONCLUSIONS
  An accurate WE in SGA fetuses is feasible using the Sabbagha formula. However, one has to be aware of the significant differences in WE between symmetric and asymmetric SGA fetuses.
authors.affiliation: Department of Gynecology and Obstetrics, Erlangen University Hospital, Erlangen, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Dammer
authors.affiliation: Department of Gynecology and Obstetrics, Erlangen University Hospital, Erlangen, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Raabe
authors.affiliation: Department of Gynecology and Obstetrics, Erlangen University Hospital, Erlangen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kehl
authors.affiliation: Institute of Medical Biometrics, Informatics and Epidemiology, University Hospital Bonn, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schmid
authors.affiliation: Department of Medical Informatics, Biometry and Epidemiology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Mayr
authors.affiliation: Department of Obstetrics and Gynaecology, Diakonie Hospitals, Hannover, Germany.
authors.forename: R L
authors.initials: RL
authors.lastname: Schild
authors.affiliation: Department of Gynecology and Obstetrics, Erlangen University Hospital, Erlangen, Germany.
authors.forename: M W
authors.initials: MW
authors.lastname: Beckmann
authors.affiliation: Department of Gynecology and Obstetrics, Erlangen University Hospital, Erlangen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Faschingbauer
mesh_terms: D002508:Cephalometry; D003430:Cross-Sectional Studies; D005260:Female; D020567:Fetal Weight / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age / Q000502:physiology*; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D055105:Waist Circumference