A study in the August 2000, issue of Obstetrics and Gynecology
(vol 96, No. 2; 207-213) shows that a new screening test which
combines a blood test and an ultrasound exam can identify over 90% of
cases of Down syndrome in the first trimester of pregnancy.
This early screening test is an alternative to the "triple test"
and has the advantage of being performed 6-8 weeks earlier in
pregnancy while detecting 30% more cases of Down syndrome. Down
syndrome is one of the most common birth defects, affecting about one
in every 600 new-born babies.
The study, entitled "First-Trimester Down Syndrome Screening Using
Dried Blood Biochemistry and Nuchal Translucency", was a collaboration
of NTD Laboratories, Huntington Station, New York, Centro Di Diagnosi
Prenatale, Palermo, Italy; GeneCare Medical Genetic Center, Chapel
Hill, North Carolina; and The George Washington University Medical
Center, Washington D.C.
Patients in the study underwent an ultrasound exam in which the
amount of fluid accumulation behind the neck of the baby, called
nuchal translucency, was measured. Additionally, a blood test was
performed on each patient in which two chemicals called free Beta hCG
and PAPP-A were measured. The results of the ultrasound measurement
and blood test were then entered into a mathematical formula to
determine the risk that the patient was carrying a baby with Down
syndrome. The screening test identifies less than 5% of patients at
high risk for Down syndrome. These increased-risk patients are then
offered a safe diagnostic procedure, either chorionic villus sampling
(CVS) or amniocentesis, which can determine, definitively, if the
patient is carrying a baby with Down syndrome. The study showed that
91% of women carrying a baby with Down syndrome were in the
The advantages of the new test, UltraScreen(R) , provided by
Perinatal Center , Las Vegas, Nevada and GeneCare Medical Genetics
Center, Chapel Hill, North Carolina, include 30% increased detection
over current Down syndrome screening tests, fewer patient reported to
be at increased risk, earlier test results, more time and more
diagnostic options for patients with increased risk results.