1. Age -- over 35 risk increases, although all women should be offered the tests

2. LMP or best dating: screening tests are very sensitive to gestational age

3. Genetic and OB Hx.  Genetic risk factors should be identified and may increase desire for testing.  

4. Determine whether the woman desires testing.

Ashkenazi Jewish

The carrier rate for Tay-Sachs is about 1 in 30

The carrier rate for Canavan is 1 in 40

The carrier rate for Familial dysautonomia is 1-32

Screening detection rates in this community are around 98%

First trimester serum screening

1. What is tested? (Hormones) and timeframe

2. What does it screen for (disorders)?

3. Normal/abnormal findings

4. Follow-up

1. Maternal serum testing between 10 weeks and 13+6 weeks to assess PAPP-A and hCG.  

2.  Assesses risk for T21 and T18

3. Normal: Screen negative, Abnormal level is set by the state

4. Follow up: if screen positive can wait until 2nd trimester bloodwork OR go ahead with genetic counseling, CVS (<15 weeks), Ultrasound (NT), or Amniocentesis (if after 15 weeks)

Non-invasive screening

1. How is the test done?  What timeframe?

2. What does it test for?

3. Normal findings

4. F/u

1. Maternal serum testing of free-floating fetal DNA.  Some tests may also look at sex chromosomal abnormalities.  Can be done any time after 10 weeks if the woman is at high risk.  High risk= age over 35, family or ob hx of disorder, or positive initial screen. 

2.  T21, T18, and T13

3. A negative cell free fetal DNA test does not ensure an unaffected pregnancy.  

4.  If positive, offer genetic counseling, invasive prenatal diagnosis (CVS or amnio) to back up diagnosis since it is new.

Nuchal Translucency

1. Procedure & timeframe

2. Normal finding

3. Follow-up

1. Ultrasound done between 11+2 to 14+2 weeks that looks at the nuchal fold to assess risk of T21.

2.  

3.

Quadruple Screen/2nd trimester screening

1. Procedure and timing

2. What does it screen for?

3. Normal findings

4. F/u

1. Serum blood draw between 15 and 20 weeks (ideally 16 to 18) that looks for Alpha Fetal Protein (AFP), hCG, 
unconjugated Estriol (E3)  and Inhibin.  Can be used alone or with 1st tri screen or NT

2. T21, T18, SLOS, and Neural tube/abdominal wall defects

3. Screen negative is normal. 

4.  Women who screen positive should be referred for genetic screening or more advanced testing (amnio)

Chorionic villus sampling (CVS)

1. Indications

2. Contraindications

3. Maternal/Fetal Risks

4. Procedure

5.  Normal findings?

6. F/u

1. Indications for CVS: diagnosis of genetic disorders that can be done sooner than amniocentesis (10-13 weeks)

2.  Contraindications of CVS include: vagnial bleeding, active genital tract infection, extreme uterine ante or retroflexion, or body habitus that precludes easy uterine access or clear sonogram

3.  Spotting, amniotic fluid leak, chorionamniotitis, <.5% risk of miscarriage.  When performed after 10 weeks, no increased risk of limb reduction.  

4. Sono-guided biopsy of CV obtained transcervically or transabodominally depending on placenta location.

5. Eupoloidy, 46 xx or 46 xy

6. F/u: Diagnositic test so results are typically seen as final.  Can refer for termination or resources for parenting depending on abnormality.  Can get indeterminate results from insufficient sample or "mosaiacism" 

Amniocentesis

1. Indication

2. Contraindication

3. Procedure & timing

4. Maternal risks

5. Fetal risks

6. Findings

7. F/u

1. Indications for amniocentesis include genetic testing and fetal lung maturity in the third trimester.  Also used for reduction of AF in polyhydramnios.  

2. Contraindications: no aboslute contraindications.  Would consider relative risk in otherwise complicated pregnancies (oligo, high risk pregnancy, etc).

3. After 16 weeks gestational age.  Under ultrasound guidance, 20-22g spinal needle is inserted transabdominally into amniotic sac.  ~20 ml of fluid is aspirated with first 1-2ml discarded for contamination.  Should avoid strenuous activity 24-48 hours after amnio.  

4. Maternal risks: isoimmunization, amnionitis (.1%), spotting or AF leakage (1%), fulminant sepsis, intraabdominal injury, hemorrhage (extermely rare)

5. Fetal risks: Prengnacy loss (1/200-1/400, but probably much lower if performed by skilled hands), needle stick to baby very rare, puncture of cord or placenta very rare

6. Karyotype without aneuploidy.  AF should be clear or have fresh blood (maternal).  Dark brown or red AF associated with poor pregnancy outcome.  Dark color is likely intra-amniotic bleeding and is associated with 1/3 pregnancy loss.  If elevated AFP found with dark color, demise will almost always occur.  Greenish AF indicates meconium and is not associated with poor prg outcomes.

7. Patient should report persistent cramping, VB, AF leaking, or fever.  intervention usually not required unless pt begins to SAB.  Results may take 1-2 weeks.  Genetic counseling or termination offered PRN.  

Percutaneous umbilical cord sampling

1. Indications

2. Contraindications

3. M/F risk

4. Procedure

5. Findings

6. F/u

1. High risk for defects

2. Maternal preference

3. Risk of SAb <2%. Bleeding, bradycardia, and infection are all risks.

4. Umbillical vein is punctured under sono guidance and fetal blood sample is obtained.

5. No genetic karyotype abnormalities. 

6. Diagnostic test so abnormal results should be referred to genetics, resources, or termination.

The integrated screening looks at PAPP-A, hCG, AFP, uE3, and Inhibin) collected during the first and second trimester bloodwork.  

The full integrated screen combines these with the NT.

1. First trimester serum screen done at 10-13 weeks

2. Results are combined with maternal age-risk assessment given to patient

if risk > 1:50 (1%), offer invasive testing (high risk screen pos) 

if risk < 1:1000 (85% of women), no further testing (screen neg) 

if risk 1:51 - 1:999 (15%), offer quad test at 15-20 weks (low risk screen positive)

Advantages: Detections rates are slightly lower than stepwise sequential testing but higher than 1st tri combined testing alone and allows women to complete their testing in a single study early in pregnancy.