title: Challenges in the diagnosis of fetal non-chromosomal abnormalities at 11-13 weeks.
abstract: OBJECTIVE
  To examine the performance of the 11-13 weeks scan in detecting non-chromosomal abnormalities.
  
  
  METHODS
  Prospective first-trimester screening study for aneuploidies, including basic examination of the fetal anatomy, in 45 191 pregnancies. Findings were compared to those at 20-23 weeks and postnatal examination.
  
  
  RESULTS
  Aneuploidies (n = 332) were excluded from the analysis. Fetal abnormalities were observed in 488 (1.1%) of the remaining 44 859 cases; 213 (43.6%) of these were detected at 11-13 weeks. The early scan detected all cases of acrania, alobar holoprosencephaly, exomphalos, gastroschisis, megacystis and body stalk anomaly, 77% of absent hand or foot, 50% of diaphragmatic hernia, 50% of lethal skeletal dysplasias, 60% of polydactyly, 34% of major cardiac defects, 5% of facial clefts and 14% of open spina bifida, but none of agenesis of the corpus callosum, cerebellar or vermian hypoplasia, echogenic lung lesions, bowel obstruction, most renal defects or talipes. Nuchal translucency (NT) was above the 95th percentile in 34% of fetuses with major cardiac defects.
  
  
  CONCLUSIONS
  At 11-13 weeks some abnormalities are always detectable, some can never be and others are potentially detectable depending on their association with increased NT, the phenotypic expression of the abnormality with gestation and the objectives set for such a scan.
authors.affiliation: Harris Birthright Research Centre of Fetal Medicine, King's College Hospital, London, UK.
authors.forename: Argyro
authors.initials: A
authors.lastname: Syngelaki
authors.forename: Teodora
authors.initials: T
authors.lastname: Chelemen
authors.forename: Themistoklis
authors.initials: T
authors.lastname: Dagklis
authors.forename: Lindsey
authors.initials: L
authors.lastname: Allan
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
mesh_terms: D000782:Aneuploidy; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging*; D005260:Female; D020139:Gastroschisis; D005865:Gestational Age; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging; D006801:Humans; D007668:Kidney / Q000002:abnormalities; D017880:Limb Deformities, Congenital / Q000000981:diagnostic imaging; D016239:MEDLINE; D009139:Musculoskeletal Abnormalities / Q000000981:diagnostic imaging; D009421:Nervous System Malformations / Q000000981:diagnostic imaging; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D016216:Ultrasonography, Prenatal