title: Ultrasonography of the fetal brainstem: a biometric and anatomical, multioperator, cross-sectional study of 913 fetuses of 21-36 weeks of gestation.
abstract: OBJECTIVE
  To establish the ultrasonographic fetal growth charts of the pons and the vermis/pons ratio on a multioperator basis in low-risk pregnancies and provide a detailed description of the anatomical and ultrasonographic criteria of normal brainstem growth.
  
  
  METHODS
  A prospective, multicenter, multioperator, ultrasonographic study was conducted on 913 fetuses aged 21-36 weeks. The anteroposterior diameter of the pons and the greatest vermal height were measured to establish a growth chart, using a mid-sagittal plane with a posterior transfontanellar approach. The LMS semiparametric statistical method was used to construct the growth charts. Three morphological structures were also examined: the pons arch and its echostructure, the bulbo-protuberential sulcus and the primary vermal fissure.
  
  
  RESULTS
  The anteroposterior diameter of the pons and the greatest vermal height were measured in 96.7% of cases. The anteroposterior diameter of the pons and vermis increased linearly with gestational age. The vermis/pons ratio was stable during pregnancy.
  
  
  CONCLUSIONS
  We have drawn the growth charts for the pons and vermis during pregnancy and described the normal ultrasound morphology of the brainstem. Knowledge of these morphological and biometric data could facilitate early screening for pontocerebellar hypoplasia.
authors.affiliation: Unité de diagnostic prénatal, Maternité Hopital Bichat, Paris, France. mirlesse.v@gmail.com
authors.forename: V
authors.initials: V
authors.lastname: Mirlesse
authors.forename: C
authors.initials: C
authors.lastname: Courtiol
authors.forename: M
authors.initials: M
authors.lastname: Althuser
authors.forename: M
authors.initials: M
authors.lastname: Duyme
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006801:Humans; D011149:Pons / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000196:embryology*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D012016:Reference Values; D018709:Statistics, Nonparametric; D016216:Ultrasonography, Prenatal / Q000379:methods*