Prenatal Diagnosis Flashcards
How do you assess the risk of a chromosomal abnormality?
Age of the mother
Previous chromosomal abnormality
What is gonadal mosaicism?
When a maternal ovary holds a line of chromosomal abnormal cells
What is nuchal translucency? When do you measure it?
Measure of fluid in the back of the neck of fetus
Between 11 weeks and 13 weeks
What factors do they use to detect downs syndrome? How effective is it?
Nuchal translucency Blood serum bhCG and PAPP-A Maternal Age Previous T21 Gestation
90% sensitivity
Which bloods are tests for down syndrome screening?
Serum bhCG - higher in DS
PAPP-A - Low in DS
What is replacing US and bloods screening?
Cell free DNA
What must you follow up a high risk cfDNA result with?
Sample of cells - CVS or AC
What can you detect with the 12 week scan?
Major defects only
What is the absent of the nasal bone indicative of?
Trisomy 21
Which scan is the best for seeing the anatomical structure of the baby?
20 week
Who gets a 16 week scan?
Those with large nuchal translucency at 13 week scan
What are some markers for T21 on the 20 week scan?
Mild hydronephrosis Short femur           Hyperechogenic bowel Nuchal edema Hypoplastic nasal bone 
Which heart anomalies must be found for their effective treatment?
Conotruncal anomalies • transposition of the great arteries • truncus arteriosus • double outlet of the right ventricle • tetralogy of Fallot
What are the advantages of MRI?
- Excellent images
- Safe
- After 20 weeks
- Fetal, abnormality - detail
- Fetal surgical workup
- Diagnostic images when US poor fetal bone, fetal lie etc.
- Neonatal radiological input into prenatal diagnosis
