title: Chorionic villus sampling for abnormal screening compared to historical indications: prevalence of abnormal karyotypes.
abstract: OBJECTIVE
  To determine the prevalence of abnormal karyotype results in women undergoing chorionic villus sampling (CVS) for abnormal first trimester screening compared to CVS for historical indications (advanced maternal age (AMA) or prior aneuploidy).
  
  
  METHODS
  Retrospective cohort of all patients undergoing CVS at Oregon Health & Science University from January 2006 to June 2010. Patients were separated based on CVS indication: (1) positive ultrasound (U/S) or serum screening; or (2) AMA or prior aneuploidy with normal or no screening. Prevalence of abnormal karyotype results were compared between groups.
  
  
  RESULTS
  Fetal karyotyping was successful in 500 of 506 CVS procedures performed. 203 CVS were performed for positive screening with 69 abnormal karyotypes (34.0%). 264 CVS were performed for historical indications with 11 abnormal karyotypes (4.2%). This difference was statistically significant (χ(2) 71.9, p < 0.001; OR 11.8 [95% CI 5.8, 24.6]). There were two age-related aneuplodies in AMA women without positive screening. 42 out of 44 AMA women diagnosed with aneuploidy (95.5%) had abnormal U/S and/or serum screening (35 U/S, 4 serum, 3 U/S and serum).
  
  
  CONCLUSIONS
  Combined ultrasound and serum screening should be recommended to all women, including AMA women, prior to undergoing invasive testing to improve risk-based counseling and minimize morbidity.
authors.affiliation: Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR 97239-3098, USA. marshani@ohsu.edu
authors.forename: Nicole E
authors.initials: NE
authors.lastname: Marshall
authors.forename: Gwen
authors.initials: G
authors.lastname: Fraley
authors.forename: Cori
authors.initials: C
authors.lastname: Feist
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Burns
authors.forename: Leonardo
authors.initials: L
authors.lastname: Pereira
mesh_terms: D059786:Abnormal Karyotype / Q000706:statistics & numerical data*; D000293:Adolescent; D000328:Adult; D000782:Aneuploidy; D015193:Chorionic Villi Sampling / Q000266:history / Q000706:statistics & numerical data*; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000453:epidemiology*; D049674:History, 21st Century; D006801:Humans; D008403:Mass Screening / Q000266:history / Q000379:methods; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000266:history / Q000379:methods / Q000706:statistics & numerical data*; D015995:Prevalence; D012189:Retrospective Studies; D055815:Young Adult