9-1: 10/21: Prenatal Screening And Diagnosis

Front 1

Amniocentesis vs Chorionic Villous Sampling

Back 1

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!!)

Front 2

Percutanoues Umbilical Blood Sampling

Back 2

Performed at 18+ (!) weeks
Fetal loss rate up to 3% (risky)

Front 3

Candidates for prenatal diagnosis?

Back 3

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

Front 4

Maternal Serum SCreening

Back 4

Non-invasive and identified high/low risk pregnancies

Front 5

Alpha fetoprotein:
General
Diagnostic Usefulness
Cutoff

Back 5

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

Front 6

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?

Back 6

40/x = 1.3 MoM

x=30 ng/mL

Front 7

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Slide 28

Back 7

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Front 8

What blood tests values would you expect in screening of Down Syndrome during the SECOND trimester?

Back 8

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.

Front 9

What blood tests values would you expect in screening of Down Syndrome during the FIRST trimester?

Back 9

Nuchal Translucensy: About 2 MoM
PAPP-A: 0.5 MoM

Front 10

For the screening of down syndrome, what are the pros/cons of screening in the first vs second trimesters?

Back 10

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

Front 11

Serum Integrated vs Full Integrated Down Syndrome Testing

Back 11

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)

Front 12

What are the advantages and disadvantages of the integrated down syndrome test?

Back 12

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.

Front 13

What screening test is almost as efficient as integrated screening and is reserved for high-risk women?

Back 13

Sequential Screening

Front 14

All women should be offered aneuploidy screening regardless of _______.

Back 14

Age

Front 15

If chorionic villus sampling is not available, what screening tests should be performed (early vs later in pregnancy)?

Back 15

Early: Serum screening

Later: Second trimester screening (AFP, uE3, hCG, inhA)