title: Towards detecting open spina bifida in the first trimester: the examination of the posterior brain.
abstract: BACKGROUND
  Our aim was to examine the value of indirect signs of open spina bifida in the mid-sagittal view of the posterior brain at the 11-13 weeks' ultrasound examination and to summarize the current evidence for the first-trimester diagnosis of spina bifida.
  
  
  METHODS
  This was a prospective study in routine obstetric population. The presence of four almost parallel lines (four-line view) in the posterior brain was recorded. Biparietal diameter (BPD), intracranial translucency (IT) and cisterna magna (CM) were measured. The ratio of IT to CM (R ratio) was calculated.
  
  
  RESULTS
  2,491 pregnancies were examined prospectively. Updated reference ranges for IT and CM were constructed. There were 3 cases with open spina bifida, and the four-line view was abnormal in 2 of them. The abnormal fetuses had smaller BPD as well as pronounced reduction in the CM and increase in the R ratio.
  
  
  CONCLUSIONS
  Examination of the posterior brain was feasible in all fetuses in the setting of the routine 11-13 weeks' ultrasound examination. Indirect signs of spina bifida are visible in the mid-sagittal view of the posterior brain, and the assessment of these structures can be a reliable tool in the early identification of this abnormality.
authors.affiliation: 1st Department of Obstetrics and Gynecology, Alexandra Maternity Hospital, Athens, Greece.
authors.forename: Dimitra
authors.initials: D
authors.lastname: Kappou
authors.forename: Ioannis
authors.initials: I
authors.lastname: Papastefanou
authors.forename: Athanasios
authors.initials: A
authors.lastname: Pilalis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kavalakis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Kassanos
authors.forename: Athena P
authors.initials: AP
authors.lastname: Souka
mesh_terms: D002946:Cisterna Magna / Q000000981:diagnostic imaging*; D018568:Crown-Rump Length; D005260:Female; D005865:Gestational Age; D006801:Humans; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D012016:Reference Values; D016137:Spina Bifida Cystica / Q000000981:diagnostic imaging*; D016216:Ultrasonography, Prenatal / Q000379:methods*