A screen negative result means that the risk of the baby being affected by Down syndrome, trisomy 18, or open neural tube defects is less than the cut-off. For example, the screen cut-off for Down syndrome with the Integrated Prenatal Screen is 1 in 200. Therefore, any result, lower than 1 in 200 is considered screen negative. The screen cut-off varies between screens and conditions.
A screen negative test can be reassuring but it is not diagnostic. Therefore, it is important to communicate that a screen negative test does not rule out the chance for the baby to have one of these conditions; a screen negative test can reduce the risk but does not eliminate it.
ALL pregnancies have a 2-3% risk for any birth defect wich may or may not be detected by prenatal screening.
Following a screen negative result, the recommended follow up varies depending upon which type of screening test the patient had. The different scenarios are listed below.
- Integrated Prenatal Screening (IPS) and Serum Integrated Prenatal Screening (SIPS):IF screen negative – ultrasound at 18-20 weeks
- First Trimester Combined Screening (FTS):IF screen negative – neural tube defect screening (MS-AFP at 15-20 weeks) and ultrasound (18-20 weeks)
- Maternal Serum Triple and Quadruple Screening:
IF screen negative – ultrasound at 18-20 weeeks