NEURAL TUBE DEFECTS An AFP MoM < 2.5 is reported as Screen-negative.An AFP MoM of >= 2.5 (singleton pregnancy) is reported as Screen-positive.DOWN SYNDROME An estimated screen risk < 1/300 is reported as Screen-negative.An estimated screen risk >= 1/300 is reported as Screen-positive.TRISOMY 18An estimated screen risk < 1/100 is reported as Screen-negative.An estimated screen risk >= 1/100 is reported as Screen-positive.
A Screen-negative result indicates that the calculated screen risk falls below the established cut-off for the open NTDs, Down syndrome and trisomy 18. A negative screen does not guarantee the absence of fetal defect. A Screen-positive result indicates an increased risk for open NTDs, Down syndrome and trisomy 18. It does not infer a definitive diagnosis, but indicates that further evaluation should be considered.