title: Agenesis of the corpus callosum: prenatal detection usually is not possible before 22 weeks of gestation.
abstract: OBJECTIVE
  To determine whether agenesis of the corpus callosum can be diagnosed prenatally with standard ultrasonographic (US) evaluation before 22 weeks of gestation.
  
  
  METHODS
  Initial scans obtained on or before 22 weeks and follow-up scans obtained in the third trimester were selected from all cases of agenesis of the corpus callosum diagnosed prenatally at the authors' laboratory. Follow-up was attained by means of review of the medical records and included imaging, karyotype, and clinical outcome.
  
  
  RESULTS
  Among 15 fetuses with callosal agenesis confirmed by means of third-trimester scans, 10 had completely normal US scans at 16-22 weeks and five had other US abnormalities. Isolated callosal agenesis was identified in six children with normal development (except one with polydactyly). Among the others, four were developmentally delayed, three died, and two others had abnormal karyotype.
  
  
  CONCLUSIONS
  Standard second-trimester US before 22 weeks of gestation may not show isolated callosal agenesis. Fetuses with this abnormality can have normal second-trimester scans and develop abnormal US findings in the third trimester.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston, Mass., USA.
authors.forename: G L
authors.initials: GL
authors.lastname: Bennett
authors.forename: B
authors.initials: B
authors.lastname: Bromley
authors.forename: B R
authors.initials: BR
authors.lastname: Benacerraf
mesh_terms: D061085:Agenesis of Corpus Callosum; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging*; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal