Prenatal Flashcards
In AFP maternal screening what is considered a significant MoM?
Above 2.5
What could be reasons for a false positive AFP maternal screening result?
Underestimated gestational age (most common)
Ventral well defect
Unrecognized twin gestation
Fetal demise
Abnormality of the fetal kidneys
Which maternal marker is elevated in Down syndrome in the First Trimester Screen?
b-hCG
What is the value of the nuchal translucency that suggests an increased risk for Trisomy 21?
> 2.5 mm
When is the quad screen performed?
Between 15w0d and 21w6d
In the quad screen analysis what is decreased and increased in Down syndrome?
Decreased: AFP, uE3
Increased: hCG, Inhibin A
In the quad screen analysis what is decreased and increased in T18/T13?
Decreased: AFP, uE3, and hCG
Inhibin A is N/A
What is associated with decreased uE3 levels?
Increased risk for Smith Lemli Opitz Syndrome
Steroid sulfatase deficiencies (X-linked icthyosis)
What is associated with extremely elevated AFP levels?
Congenital nephrotic syndrome
What is the false positive rate in maternal serum screening?
5%
When is a CVS performed?
11-14 wks
What are the drawbacks of CVS?
Placental mosaicism
What is the lower limit of cell-free DNA for a reliable result with NIPT?
4%
What is the size range for detecting del/dup on karyotype?
5-10 MB
If mosaicism is detected in CVS, what percentage of follow-up amniocentesis shows mosaicism?
10%