Cytogenetic aspects of the Canadian Early and Mid-trimester Amniotic Fluid Trial (CEMAT)

Elizabeth J.T. Winsor, Darrell J. Tomkins, Dagmar Kalousek, Sandra Farrell, Philip Wyatt, Yao Shan Fan, Ronald Carter, Hungshu Wang, Louis Dallaire, Patrice Eydoux, J. Philip Welch, Angelika Dawson, Jim C.C. Lin, Joel Singer, Jo Ann Johnson, R. Douglas Wilson

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Cytogenetic results from a large multicentre randomized controlled study of 2108 amniotic fluids obtained at 11 + 0-12 + 6 weeks (EA) and 1999 fluids at 15 + 0-16 + 6 weeks (MA) were compared. There was no statistically significant difference in the rate of chromosome abnormalities (EA = 1.9 percent; MA = 1.7 per cent) or level III mosaicism (EA = 0.2 per cent; MA = 0.2 per cent) between the groups. Level I and Level II mosaicism occurred more frequently in MA. Maternal cell contamination was not significantly different between the groups, but maternal cells only were analysed from one bloody EA fluid. The number of repeat amniocenteses because of cytogenetic problems was 2.2 per cent in the EA group compared with only 0.3 per cent in the MA group. On average, culture of EA fluids required one day more than MA fluids. Although both culture success (97.7 per cent) and accuracy (99.8 per cent) were high for patients randomized to the EA group, routine amniocentesis prior to 13 weeks' gestation is not recommended for clinical reasons including an increased risk of fetal loss and talipes equinovarus.

Original languageEnglish (US)
Pages (from-to)620-627
Number of pages8
JournalPrenatal Diagnosis
Issue number7
StatePublished - 1999
Externally publishedYes


  • Chromosome culture
  • Early amniocentesis
  • Maternal cell contamination

ASJC Scopus subject areas

  • Genetics(clinical)
  • Obstetrics and Gynecology


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