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14 Cards in this Set
- Front
- Back
Risk factors to consider pre-natal screening
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- Age
- Diabetes - Any personal/family history of genetic defects (NTD, chromosomal, etc.) - Abnormal ultrasound - Abnormal serum screening |
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Non-invasive screening techniques
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NOT diagnostic, just indicators
- Maternal serum screening - Triple Screen - Quad screen - 1st trimester screen - Combined screen - ccffDNA testing - Ultrasonography |
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Maternal serum screen
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Detects MS-AFP (maternal serum alpha-fetoprotein)
- Too high - possible NTD's - Too low - possible triosomies (18 and 21) |
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Triple screen
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1) AFP
2) hCG (human chorionic gonadotropin) 3) uE3 (unconjugated estradiol) |
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Quad screen
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1) AFP
2) hCG 3) uE3 4) Inhibin |
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First trimester screen
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1) hCG
2) PAPP-A (pregnancy-associated plasma protein-A) |
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Combined screen
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1st trimester screen + NT (Nuchal translucency - thickness)
- Thick NT indicates greater risk of trisomy - Together, these have greater than 90% detection accuracy |
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ccffDNA
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Circulating cell-free fetal DNA
- found in maternal serum and purified - test for trisomy 13, 18, 21 - Only recommended if positive 1st trimester screen or other family risk factors - Best after 10 weeks |
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Positive indicators of Trisomy 18
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- low AFP
- low uE3 - low PAPP-A - low hCG - Thick NT *** Inhibin not great test for 18 |
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Positive indicators of Trisomy 21
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- low AFP
- low uE3 - low PAPP-A - HIGH hCG - Thick NT *** Also high inhibin (if using quad screen) |
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Invasive techniques
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- Amniocentesis
- Chorionic villus sampling - Percutaneous umbilical blood sampling (cordocentesis) |
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Amniocentesis
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Take amniotic fluid via syringe
- 15-16 weeks - Isolate, test fetal cells for AFP and other abnormalities - Risk of miscarriage 1/2-300, also infection, cramping, etc. |
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Chorionic villus sampling (CVS)
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Take some tissue to biopsy
- 11-12 weeks - Risk of miscarriage 1/1-200, others same as amniocentesis |
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NTD
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Greatly reduced by folic acid intake
- 0.4mg for women with no history, 4mg for those who have - Higher MSAFP for ONTD's! |