Combining first and second trimester markers for Down syndrome screening: think twice.

Aims: This study compares different screening strategies for the detection of Down syndrome and considers practical implications of using multiple screening protocols.

Methods: The performance characteristics of each screening strategy were assessed based on datasets of Down syndrome (n=11) and unaffected pregnancies (n=1006) tested in both first and second trimester, as well as data from first trimester (n=18,901) and second trimester (n=40,748) pregnancies.

Results: For a detection rate of 91%, the false positive rates for integrated and serum integrated screening were 2.

Trends in state/population-based Down syndrome screening and invasive prenatal testing with the introduction of first-trimester combined Down syndrome screening, South Australia, 1995-2005.

Objective: The purpose of this study was to review trends in the us of maternal serum Down syndrome screening and invasive prenatal testing before and after the introduction of a state-based first-trimester combined Down syndrome screening program.

Study Design: A retrospective population-based study was performed on first- and second-trimester Down syndrome screening, invasive prenatal testing, and prenatal detection of Down syndrome from 1995 to 2005 in South Australia with data from state-based registers. Chi-square tests were used to evaluate trends.