Prenatal Diagnosis - Lecture 10 Flashcards
1
Q
Screening
A
- Used for low risk patients
- May lead to diagnostic testing
- Low cost
- Low procedure related risk
2
Q
Diagnostic
A
- For patients at increased risk
- May have higher financial cost
- Higher procedure related risk
- Leads to definitive diagnosis
3
Q
Screening Options
A
- First trimester combined screening (ultrasound and maternal serum screening)
- NIPT
4
Q
Diagnostic options
A
- Amniocentesis
- CVS
- Cordocentesis
- PGD
5
Q
Indications for prental diagnosis - Pre-Pregnancy
A
- Advanced maternal age - >35
- Previous child with autosomal trisomy
- Parental structural chromosomal abnormalities
- Family history of diagnosable genetic disorder
- Previous child (or pt or spouse) with neural tube defect
6
Q
Indications for prenatal diagnosis - During pregnancy
A
- Abnormal screening test
- Ultrasound findings associated with a genetic disorder
- All patients who desire definitive diagnosis after counseling (regardless of risk)
7
Q
Amniocentesis
A
- At or after 15 weeks
- Earlier amnio used to be offered but too much fluid was withdrawn for amount available
- Results available in ~2 weeks
- Preliminary FISH can be obtained in 24-48 hours
- Risk 0.1% - 1% of SAB
8
Q
Neural Tube Defect Diagnosis
A
- Measure alpha fetoprotein
- Measure acetylcholinesterase
- Efficacy of ultrasound
9
Q
Chorionic Villus Sampling (10-13 weeks)- Advantages
A
- Earlier diagnosis
- Pt privacy (no one will know about the pregnancy if she decides for termination)
- Quicker results
- Psychosocial and emotional attachment
- Safer pregnancy termination
10
Q
Chorionic Villus Sampling (10-13)- Disadvantages
A
- Earlier procedure
- Too early for AFP pickup to determine neural tube defects
- Placental mosaicism
- Higher pregnancy loss rate (0.6-0.8% higher than amnio)
- Limb reduction abnormalities
11
Q
NIPT
A
Isolation of cell free DNA from maternal plasma
Requires minimum of 4% fetal DNA
