Downs syndrome: antenatal testing Flashcards
what is used to assess downs syndrome?
nuchal translucency measurement + serum B-HCG + pregnancy-associated plasma protein A (PAPP-A)
combined test
quadruple test
when is the tests done?
11 - 13+6 weeks
what results suggest downs syndrome?
↑ HCG, ↓ PAPP-A, thickened nuchal translucency
what happens to the hcg in patau’s (trisomy 13) and Edwards syndrome (trisomy 18)
low
similar results
when and who is the quadruple test offered to?
if women book later in pregnancy the quadruple test should be offered between 15 - 20 weeks
what does the quadruple test measure?
alpha-fetoprotein, unconjugated oestriol, human chorionic gonadotrophin and inhibin A
results of alpha-fetoprotein, unconjugated oestriol, human chorionic gonadotrophin and inhibin A in Downs syndrome?
alpha-fetoprotein low
unconjugated oestriol low
human chorionic gonadotrophin high
inhibin A high
results of alpha-fetoprotein, unconjugated oestriol, human chorionic gonadotrophin and inhibin A in Edwards syndrome
alpha-fetoprotein low
unconjugated oestriol low
human chorionic gonadotrophin low
inhibin A normal
alpha-fetoprotein, unconjugated oestriol, human chorionic gonadotrophin and inhibin A in neural tube defects
alpha-fetoprotein high
unconjugated oestriol normal
human chorionic gonadotrophin normal
inhibin A normal
what is a non-invasive pre-natal screening test?
If a woman has a ‘higher chance’ results she will be offered a second screening test (NIPT) or a diagnostic test (e.g. amniocentesis or chorionic villus sampling (CVS).
