"Prenatal diagnosis is useful in managing a pregnancy with an identified fetal abnormality and may allow for planning and coordinating care during delivery and the neonatal period," the authors provide as background information. "... invasive diagnostic tests (e.g., amniocentesis, chorionic villus sampling, percutaneous umbilical blood sampling) for fetal chromosomal abnormalities are highly reliable, but the procedure used for each test carries a risk for loss of pregnancy. Many patients who are candidates for these tests decline them because of the risk of pregnancy loss." The authors continue, "... the use of free fetal DNA for detecting chromosomal abnormalities has been limited by the seemingly low percentage of free fetal DNA in the maternal circulation."
Ravinder Dhallan, M.D., Ph.D., from Ravgen, Inc., Columbia, Md., and colleagues, analyzed blood samples from pregnant women to determine if the percentage of free fetal DNA could be increased by using formaldehyde to stabilize blood cell membranes and reduce the number of the mother's blood cells that are destroyed during sample collection, handling, and processing, which reduces the amount of maternal DNA released, thereby increasing the percentage of fetal DNA. The study was conducted in two phases from January through February 2002 at one clinical site and March 2002 through May 2003 at a network of 27 clinical sites in 16 U.S. states. The first phase collected two samples of blood from ten pregnant women - one blood sample was treated with formaldehyde and the other blood sample was untreated. In the second phase, all 69 blood samples were treated with formaldehyde.
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