11/05 - Prenatal Diagnosis Flashcards Preview

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Flashcards in 11/05 - Prenatal Diagnosis Deck (18)
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1

Prenatal Diagnosis

Screening:
- For low risk patients
- Low financial cost
- Low procedure-related risk
- Positive test LEADS to diagnostic test

Diagnosis:
- For patients at increased risk
- May have higher financial cost
- Higher procedure-related risk
- Positive test considered definitive

2

2014 Prenatal Diagnosis Screening and Diagnosis steps

Screening:
1) Combined First Trimester (studies skin on back of neck and combine that with biomarkers in blood test on Mom)
2) Integrated/Sequential/Contingent
3) Second Trimester Multiple Marker ("Quad")
4) Ultrasound
5) NIPT (Cell-free DNA; blood test on mom)

Diagnosis:
1) Amniocentesis
2) Chorionic Villus sampling
3) Cordocentesis
4) Pre-implantation Genetic Diagnosis (PGD)

3

Prenatal Diagnosis Indications

Pre-pregnancy:
1) Maternal age >35 at due date
2) Previous child with autosomal trisomy
3) Parental structural chromosomal abnormality
4) Family history of a diagnosable genetic disorder
5) Previous child (or patient or spouse) with NTD (*not CVS)

During Pregnancy:
1) Abnormal screening test
- First Trimester Screen
- Second Trimester Maternal Serum Screen
- Positive NIPT
2) Ultrasound findings associated with a diagnosable genetic disorder

Various non-genetic indications...Fetal lung maturity, infections, etc.

*All patients desiring definitive diagnosis should be offered it, after counseling

4

When is Amniocentesis done (time-wise)

Ideally between 15 - 22 weeks to allow all therapeutic options.

- COULD do it earlier but higher complication rates before 14 weeks.

5

Amniocentesis Technique

- In amniocentesis, a hollow needle is inserted through the mother's abdomen into the uterus, and amniotic fluid is drawn for analysis

6

When are results available for amniocentesis?

- Less than 2 weeks after procedure
- Preliminary or FISH results in 24-48 hours

7

Risks of Amniocentesis

- 0.1 - 1.0% procedure related risk
Somewhere between 1/100 and 1/1000 losses

8

Neural Tube Defect Diagnosis in Amniocentesis

- Measurement of alpha fetoprotein
- Measurement of acetyl cholinsterase
- Efficacy of Ultrasound

9

Chorionic Villus Sampling (CVS) Advantages

- Earlier diagnosis
- Patient privacy (for those patients that might consider termination, easier if not everyone knows she's pregnant)
- Quicker results
- Psychological and emotional attachments
- Safer pregnancy termination

10

Chorionic Villus Sampling (CVS) Disadvantages

- Earlier procedure (nature may have taken care of this anyways)
- Lack of AFP Information
- Placental Mosaicism
- Higher pregnancy loss rate
- Limb reduction abnormalities

11

1983 History of CVS (big one)

- Report of trisomy 21 at 11 weeks, within 5 hours using ultrasound guidance and a flexible catheter

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When do you do CVS?

10-13 weeks

13

When are results available for CVS?

results pretty quickly by looking at cells that are actively dividing and can get some information pretty fast

14

Procedure related risks of CVS

- 0.6-0.8% greater procedure related risk than amniocentesis

- Some more recent studies suggest that CVS is no more risky than amniocentesis

15

Limb Reduction Abnormalities

- Tapered fingers or toes or missing tips of fingers or toes.. Some clusters of cases happened in Europe and US when first introduced.
- Increased risk at <10 weeks
- Increased risk in programs with higher loss rates

16

Cordocentesis

- Percutaneous Umbilical Blood Sampling

Diagnostic (Previously, Rapid karyotype)
- Fetal blood: hematocrit
- Platelets
- Infection

Therapeutic:
- Transfusion
- Drugs

17

When do you do a cordocentesis?

- 18-20 weeks

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Risks of Cordocentesis

Between 1-2% of increased loss rate