Repeat testing in antenatal screening for Down syndrome using dimeric inhibin-A in combination with other maternal serum markers

Abstract

The effect on screening performance of collecting a second fresh blood sample in antenatal screening for Down syndrome has been previously reported for the commonly used double and triple tests. Recently, dimeric inhibin-A has been used with the triple test (together constituting the quadruple test) in several centres and here we assess the effect of repeat testing using inhibin-A. Routine repeat testing using the quadruple test did not yield a material increase in performance compared with having no repeat testing. For a 5% false-positive rate the increase in detection rate was only about 3-5 percentage points; a modest increase which is probably not worthwhile in the light of the extra cost and delay.