Evaluation of Down syndrome screening strategies

Women contemplating pregnancy today have many different Down syndrome screening protocols from which to choose. Sensitive and specific first and second trimester screening protocols are now widely available, and strategies that combine first and second trimester markers are moving from investigational use into the clinical arena. Modeling indicates that a high detection rate (85%) associated with a very low screen positive rate (1.3%) can be achieved with contingent screening, in which all women undergo first trimester screening and only a portion (25%) go on to second trimester screening.