title: The association between prenatal atrioventricular septal defects and chromosomal abnormalities.
abstract: OBJECTIVE
  Atrioventricular septal defect is associated with a high risk of a chromosomal abnormality, particularly trisomy 21. The aim of this study is to assess the rate of trisomy 21 in fetuses diagnosed with an atrioventricular septal defect and to examine the influence of prior screening on the rate of trisomy 21.
  
  
  METHODS
  Electronic ultrasound database was searched to identify fetuses diagnoses with an atrioventricular septal defect from 2002 to 2014. Rate of trisomy 21 and other aneuploidies was calculated among fetuses with normal situs. The prevalence of trisomy 21 and other aneuploidies was assessed in women with low and high first trimester risk for trisomy 21, using a cut-off value of 1:150 and 1:250.
  
  
  RESULTS
  A total 110 fetuses with a diagnosis of atrioventricular septal defect were identified. Among the 98 fetuses with normal situs, the prevalence of trisomy 21 was 46% (95% CI: 36-56%). Using a 1:150 threshold, the rate of trisomy 21 within the low-risk group was 41% (95% CI: 27-57%) while in the high-risk group it was 70% (95% CI: 52-83%), significantly higher than in the low risk group (p=0.028). Similar results were obtained when the 1:250 threshold was applied (66% versus 41%, p=0.055).
  
  
  CONCLUSIONS
  The rate of trisomy 21 among fetuses identified with an atrioventricular septal defect in the second trimester is high even in those that undergo first trimester combined screening. Some fetuses with a high-risk screening result show a normal karyotype. Therefore, an offer of an invasive procedure to check fetal karyotyping is indicated. Knowledge of these rates may be helpful for parents in the decision making process.
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, United Kingdom; Department of Neuroscience, Reproductive Sciences and Dentistry, School of Medicine, University of Naples Federico II, Naples, Italy.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Morlando
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, United Kingdom. Electronic address: abhide@sgul.ac.uk.
authors.forename: Amarnath
authors.initials: A
authors.lastname: Bhide
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, United Kingdom.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Familiari
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, United Kingdom.
authors.forename: Asma
authors.initials: A
authors.lastname: Khalil
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, United Kingdom.
authors.forename: José
authors.initials: J
authors.lastname: Morales-Roselló
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, United Kingdom.
authors.forename: Aris T
authors.initials: AT
authors.lastname: Papageorghiou
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, United Kingdom; Royal Brompton Hospital, London, United Kingdom.
authors.forename: Julene S
authors.initials: JS
authors.lastname: Carvalho
mesh_terms: D000015:Abnormalities, Multiple / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000196:embryology / Q000453:epidemiology; D000328:Adult; D000782:Aneuploidy; D025063:Chromosome Disorders / Q000175:diagnosis / Q000196:embryology / Q000453:epidemiology; D004314:Down Syndrome / Q000175:diagnosis* / Q000196:embryology / Q000453:epidemiology; D057286:Electronic Health Records; D005260:Female; D005500:Follow-Up Studies; D005820:Genetic Testing; D006343:Heart Septal Defects / Q000000981:diagnostic imaging* / Q000196:embryology / Q000453:epidemiology; D006801:Humans; D007621:Karyotyping; D008131:London / Q000453:epidemiology; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis; D015995:Prevalence; D012306:Risk; D062606:Tertiary Care Centers; D016216:Ultrasonography, Prenatal
keywords: AVSD; Atrioventricular septal defect; Chromosomal abnormalities; Combined risk; First trimester risk; Trisomy 21