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Antenatal Screening
Aka: Antenatal Screening, Prenatal Diagnosis
- Protocol: First Trimester Screening
- Combination screening recommended
- Pregnancy-Associated Plasma Protein A (PAPP-A) and
- Nuchal Translucency (performed at 11 to 13 weeks)
- Efficacy
- Detecting Trisomy 21 (Down Syndrome) in all women
- Test Sensitivity: 78-89% (>90% if age over 35 years)
- Test Specificity: 95% (only 78-86% if age over 35 years)
- Detecting Trisomy 18
- Test Sensitivity: 90%
- Test Specificity: 98%
- Additional findings
- Low levels of both markers are associated with adverse pregnancy outcomes
- Protocol: Second Trimester Screening
- Combination screening
- Serum testing (Quad Screen) and
- Second Trimester Ultrasound
- See Trisomy Findings on Fetal Ultrasound
- Efficacy: Amniocentesis with Quad Screen
- Test Sensitivity: Approaches 90%
- Test Specificity: 95-8%
- Protocol: Invasive Testing to confirm chromosomal abnormalities
- Chorionic Villus Sampling (10-13 weeks)
- Amniocentesis (16-18 weeks)
- References
- Anderson (2009) Am Fam Physician 79(2): 117-23