title: Prevalence of maternal cell contamination in amniotic fluid samples.
abstract: OBJECTIVE
  The purpose of this study is to evaluate the incidence of maternal cell contamination (MCC) in the first few milliliters of amniotic fluid withdrawn during amniocentesis.
  
  
  METHODS
  A prospective observational study was performed. The initial 2-3 ml of amniotic fluid withdrawn during amniocentesis was divided into direct analysis (uncultured) and cultured samples. A matching maternal buccal swab was obtained for MCC testing. MCC was determined by short-tandem repeat analysis. The primary outcome was measurement of clinically significant contamination (MCC >5%). Secondary outcomes included the determination of risk factors associated with MCC >5%. Outcomes were assessed by fisher's exact, independent t-test, binary logistic regression, and ANOVA.
  
  
  RESULTS
  Direct analysis measured clinically significant contamination (MCC > 5%) in 26% of specimens, while any amount of MCC was present in 68% of specimens. Cultured specimens had MCC > 5% in 2%, and any amount of MCC in 24%. Only blood-tinged fluid was associated with an increased risk for MCC > 5%. Larger volumes of the discard sample were not associated with increased incidence of MCC greater than 5%.
  
  
  CONCLUSIONS
  A significant amount of MCC is present with direct analysis of the initial few milliliters of amniotic fluid withdrawn and is not influenced by the volume of the discard sample. Our results suggest that the first few milliliters of amniotic fluid be removed and discarded when direct analysis is utilized for prenatal genetic testing.
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , Indiana University School of Medicine , Indianapolis , IN , USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Weida
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , Indiana University School of Medicine , Indianapolis , IN , USA.|b Division of Clinical Pharmacology, Department of Medicine , Indiana University School of Medicine , Indianapolis , IN , USA.
authors.forename: Avinash S
authors.initials: AS
authors.lastname: Patil
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , Indiana University School of Medicine , Indianapolis , IN , USA.
authors.forename: Frank P
authors.initials: FP
authors.lastname: Schubert
authors.affiliation: c Division of Diagnostic Genomics, Department of Medical and Molecular Genetics , Indiana University School of Medicine , Indianapolis , IN , USA , and.
authors.forename: Gail
authors.initials: G
authors.lastname: Vance
authors.affiliation: c Division of Diagnostic Genomics, Department of Medical and Molecular Genetics , Indiana University School of Medicine , Indianapolis , IN , USA , and.
authors.forename: Holli
authors.initials: H
authors.lastname: Drendel
authors.affiliation: c Division of Diagnostic Genomics, Department of Medical and Molecular Genetics , Indiana University School of Medicine , Indianapolis , IN , USA , and.
authors.forename: Angela
authors.initials: A
authors.lastname: Reese
authors.affiliation: c Division of Diagnostic Genomics, Department of Medical and Molecular Genetics , Indiana University School of Medicine , Indianapolis , IN , USA , and.
authors.forename: Stephen
authors.initials: S
authors.lastname: Dlouhy
authors.affiliation: c Division of Diagnostic Genomics, Department of Medical and Molecular Genetics , Indiana University School of Medicine , Indianapolis , IN , USA , and.
authors.forename: Shaochun
authors.initials: S
authors.lastname: Bai
authors.affiliation: d Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , Icahn School of Medicine at Mount Sinai , New York , NY , USA.
authors.forename: Men-Jean
authors.initials: MJ
authors.lastname: Lee
mesh_terms: D000649:Amniocentesis / Q000379:methods* / Q000592:standards; D000653:Amniotic Fluid / Q000737:chemistry / Q000166:cytology*; D002478:Cells, Cultured; D059018:DNA Contamination; D005260:Female; D006801:Humans; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors
keywords: Maternal cell contamination; amniocentesis; microarray; prenatal diagnosis