Tuesday, March 1, 2011

Down' Syndrome Screenings

Down syndrome is also known as trisomy 21. It is the most common identifiable cause of learning disorder. Average life expectancy is 50 years old. About 1 in 10 die before age of 10.

The risk of down's syndrome in directly related to maternal age
  • 25 years 1 in 1500
  • 30 years 1 in 900
  • 35 years 1 in 400
  • 40 years 1 in 100
  • 45 years 1 in 30
Screening Test for Down's Syndrome: Combine test
  • 11 to 13 weeks
  • Ultrasound: Nuchal Translucency (NT)
  • Blood test:
  • - Pregnancy associated plasma protein A (PAPP-A)
  • - B-HCG

Interpreting the combine screening test
  • 90% sensitive (detects 90%)
  • 5% false positive
Screening Test for Down's Syndrome: Integrated test
  • NT at 10 to 13 weeks
  • PAPPA 10 weeks
  • Oestriol, HCG, AFP, inhibin A in 15 weeks (Quadruple test)
Interpretation:
  • 85% Sensitive
  • 1.2% False positive
  • Results out only after 15 weeks
These are the 2 most common tests. Other include the Quadruple test, serum integrated test (PAPP-A 10 weeks and quadruple test 15 weeks).

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