serum screening for Down's syndrome

Last reviewed 01/2018

Serum screening for Down's syndrome

• Screening for Down's syndrome can be undertaken from 10 weeks + 0 days to 20 weeks + 0 days of pregnancy. The recommended method of screening for Down's syndrome is using the Combined Test
  
  
• Screening for Down's syndrome should be performed by the end of the first trimester (14 weeks and 1 day), but provision should be made to allow later screening (which could be as late as 20 weeks 0 days) for women booking later in pregnancy
  
  
• Tests should meet a detection rate (DR) of more than 90%, for a screen positive rate (SPR) of less than 2% (of affected pregnancies) for England for those undergoing combined screening
  
  
• The following tests meet current standards:
  • From 10 weeks + 0 days to 14 weeks + 1 day the combined test (maternal serum - hCG and PAPP-A and nuchal translucency scan) is the recommended screening strategy.
    • The blood sample (or serum sample) can be taken between 10 weeks and 0 days and 14 weeks and 1 day's gestation. The blood sample uses a combination of free beta-hCG and placenta associated plasma protein A (PAPP-A).
  • The NT and CRL measurement can be taken between 11 weeks and 2 days and 14 weeks and 1 days gestation o From 14 weeks + 2 days to 20 weeks + 0 days, the quadruple test (maternal serum - hCG, AFP, uE3, inhibin A)) for those presenting later is the recommended screening strategy

For more information then see www.fetalanomalyscreening.nhs.uk.

Reference:

• 1. NICE. Antenatal care: routine care for the healthy pregnant woman. England: NHS National Institute for Health and Clinical Excellence; 2008 Mar. Report No.: Clinical guidelines CG62
• 2. NHS Fetal Anomaly Screening Programme. Antenatal screening - working standards for Down's syndrome screening 2007. NHS FASP; 2007.
• 3. NHS Fetal Anomaly Screening Programme. Consent standards for screening fetal anomalies during pregnancy 2007. NHS FASP; 2007.
• 4. NHS Fetal Anomaly Screening Programme. NHS fetal Anomaly screening programme - screening for Down's syndrome: UK NSC Policy recommendations 2007-2010: Model of Best Practice. Department of Health; 2008.
• 5. Kirwan D, NHS FASP. 18+0 to 20+6 weeks fetal anomaly scan -National standards and guidance for England 2010. Exeter, England: NHS Fetal Anomaly Screening Programme; 2010.