title: Biparietal diameter-to-crown-rump length disproportion in first-trimester fetuses with holoprosencephaly.
abstract: OBJECTIVE
  To determine whether the biparietal diameter measurement is altered in first-trimester fetuses with holoprosencephaly.
  
  
  METHODS
  Cases of holoprosencephaly were collected retrospectively from 4 fetal medicine centers, and first-trimester biparietal diameter measurements were reviewed. The diagnosis of holoprosencephaly was established sonographically by the detection of abnormal choroid plexus morphologic characteristics (absent "butterfly" sign) and the identification of a monoventricular cerebral cavity on axial views of the fetal brain. The proportion of fetuses with biparietal diameter measurements below the 5th percentile for crown-rump length was determined.
  
  
  RESULTS
  Among 45 cases of holoprosencephaly reviewed, 43 had information on both biparietal diameter and crown-rump length measurements. The biparietal diameter was below the 5th percentile for crown-rump length in 14 (32.6%) fetuses. Chromosomal analysis was available in 41; no statistically significant difference in biparietal diameter measurement between those with associated chromosomal anomalies and those without anomalies was noted. A supplementary analysis using head circumference measurement showed an even greater proportion of fetuses with holoprosencephaly with measurements below the 5th percentile for crown-rump length (18 of 42 [42.9%]).
  
  
  CONCLUSIONS
  One-third of first-trimester fetuses with a sonographic diagnosis of holoprosencephaly had a biparietal diameter that was smaller than expected for crown-rump length. In this subset of fetuses, the evaluation of intracranial anatomy for signs of holoprosencephaly may be more difficult to perform due to the smaller size of the brain. Therefore, the detection of a biparietal diameter below the 5th percentile as expected from crown-rump length on the first-trimester scan may be a warning sign of holoprosencephaly and should prompt a detailed examination of the intracranial anatomy.
authors: Fetal Medicine Center, Fetal Medicine Interest Group GIMEF, Santiago, Chile (W.S., A.E.W.); Medical-Genetics Department, Moscow Regions Research Institute of Obstetrics and Gynecology, Moscow, Russia (E.A., N.O.); Delta-Ultrasound Diagnostic Center for Obstetrics and Gynecology, Madrid, Spain (P.M.-T.); and Monash Ultrasound for Women, Melbourne, Victoria, Australia (S.M.). fetalmed@yahoo.com.
authors: Waldo
authors: W
authors: Sepulveda
authors: Fetal Medicine Center, Fetal Medicine Interest Group GIMEF, Santiago, Chile (W.S., A.E.W.); Medical-Genetics Department, Moscow Regions Research Institute of Obstetrics and Gynecology, Moscow, Russia (E.A., N.O.); Delta-Ultrasound Diagnostic Center for Obstetrics and Gynecology, Madrid, Spain (P.M.-T.); and Monash Ultrasound for Women, Melbourne, Victoria, Australia (S.M.).
authors: Amy E
authors: AE
authors: Wong
authors: Fetal Medicine Center, Fetal Medicine Interest Group GIMEF, Santiago, Chile (W.S., A.E.W.); Medical-Genetics Department, Moscow Regions Research Institute of Obstetrics and Gynecology, Moscow, Russia (E.A., N.O.); Delta-Ultrasound Diagnostic Center for Obstetrics and Gynecology, Madrid, Spain (P.M.-T.); and Monash Ultrasound for Women, Melbourne, Victoria, Australia (S.M.).
authors: Elena
authors: E
authors: Andreeva
authors: Fetal Medicine Center, Fetal Medicine Interest Group GIMEF, Santiago, Chile (W.S., A.E.W.); Medical-Genetics Department, Moscow Regions Research Institute of Obstetrics and Gynecology, Moscow, Russia (E.A., N.O.); Delta-Ultrasound Diagnostic Center for Obstetrics and Gynecology, Madrid, Spain (P.M.-T.); and Monash Ultrasound for Women, Melbourne, Victoria, Australia (S.M.).
authors: Natalia
authors: N
authors: Odegova
authors: Fetal Medicine Center, Fetal Medicine Interest Group GIMEF, Santiago, Chile (W.S., A.E.W.); Medical-Genetics Department, Moscow Regions Research Institute of Obstetrics and Gynecology, Moscow, Russia (E.A., N.O.); Delta-Ultrasound Diagnostic Center for Obstetrics and Gynecology, Madrid, Spain (P.M.-T.); and Monash Ultrasound for Women, Melbourne, Victoria, Australia (S.M.).
authors: Pilar
authors: P
authors: Martinez-Ten
authors: Fetal Medicine Center, Fetal Medicine Interest Group GIMEF, Santiago, Chile (W.S., A.E.W.); Medical-Genetics Department, Moscow Regions Research Institute of Obstetrics and Gynecology, Moscow, Russia (E.A., N.O.); Delta-Ultrasound Diagnostic Center for Obstetrics and Gynecology, Madrid, Spain (P.M.-T.); and Monash Ultrasound for Women, Melbourne, Victoria, Australia (S.M.).
authors: Simon
authors: S
authors: Meagher
mesh_terms: D018568:Crown-Rump Length; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016142:Holoprosencephaly / Q000000981:diagnostic imaging* / Q000196:embryology / Q000503:physiopathology; D006801:Humans; D010296:Parietal Lobe / Q000000981:diagnostic imaging* / Q000196:embryology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal
keywords: biparietal diameter; fetal sonography; first trimester; holoprosencephaly; obstetric ultrasound; prenatal diagnosis