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15 Cards in this Set
- Front
- Back
Amniocentesis vs Chorionic Villous Sampling
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Amniocentesis: performed between 15-20 weeks; obtain fetal cells in amniotic fluid
CVS: performed 10-12 weeks gestation, obtain villous tissue from placenta (higher risk!!) |
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Percutanoues Umbilical Blood Sampling
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Performed at 18+ (!) weeks
Fetal loss rate up to 3% (risky) |
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Candidates for prenatal diagnosis?
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Maternal/family history:
PRevious child w/chrom abnormality Recurrent abortions/infertility Exposure to viral infections (rubella, cytomegalovirus) Meds/env hazards Male relatives with DMD or hemophilia |
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Maternal Serum SCreening
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Non-invasive and identified high/low risk pregnancies
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Alpha fetoprotein:
General Diagnostic Usefulness Cutoff |
Produced by yolk sac and fetal liver, excreted in amniotic fluid (via urine)
Useful for neural tube defects; will be in higher amount in amniotic fluid because open neural tube leaks alpha-fetoprotein leaks out AFP > 2.02 MoM = screen positive; but need amniocentesis for DIAGNOSIS |
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If a pregnant woman has a maternal serum AFP of 40 ng/Ml, and a multiple of median of 1.3.
What is the median serum AFP? |
40/x = 1.3 MoM
x=30 ng/mL |
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1:29:08
Slide 28 |
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What blood tests values would you expect in screening of Down Syndrome during the SECOND trimester?
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Done in second trimester of pregnancy.
AFP and uE3 reduced (low MoM) hCG and inhA twice as high (high MoM) This is only screening. Need amniocenteses for confirmatory. Using maternal age alone for testing will only catch 1/3 of Down Syndrome babies. |
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What blood tests values would you expect in screening of Down Syndrome during the FIRST trimester?
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Nuchal Translucensy: About 2 MoM
PAPP-A: 0.5 MoM |
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For the screening of down syndrome, what are the pros/cons of screening in the first vs second trimesters?
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First trimester: earlier diagnosis, more privacy, safer procedures; requires CVS (can't do amnio)
Will still need to wait for 15 weeks to screen Neural Tube Defects (so will need second trimester screening) First trimester NT reads require training/certification/QA |
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Serum Integrated vs Full Integrated Down Syndrome Testing
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Serum Integrated: PAPP-A + Quad Markers (AFP, uE3, hCG, inhA)
Full Integrated: Nuchal Translucency + PAPP-A + quad markers Both tests combine results of associated tests into single result (risk) |
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What are the advantages and disadvantages of the integrated down syndrome test?
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Advantages: Safest, most effective
Preserves AFP screening for open NTDs Disadvantages: Antenatal dx or termination of pregnancy at 16-17 weeks instead of 13 weeks. |
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What screening test is almost as efficient as integrated screening and is reserved for high-risk women?
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Sequential Screening
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All women should be offered aneuploidy screening regardless of _______.
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Age
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If chorionic villus sampling is not available, what screening tests should be performed (early vs later in pregnancy)?
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Early: Serum screening
Later: Second trimester screening (AFP, uE3, hCG, inhA) |