1st trimester analyte patterns
T21: HCG high, PAPPA low
T18: HCG and PAPPA low
2nd trimester analyte patterns
T21: HCG and INH high; AFP and UE3 low
T18: All four are low
ONTDs/abdominal wall defects: AFP.high
Dating changes
If further along than expected: your HCG will look low > more likely to get a positive for T18
If not as far along as expected: your HCG will look high > more likely to get a positive for T21
Very low HCG increases the risk for?
SAB
Very low UE3 increases the risk for?
SLOS
X-linked icthyosis (steroid sulfatase deficiency)
CAH
Placental aromatase deficiency
High inhibin increases the risk for?
HELLP, triploidy, loss of a twin
Low inhibin increases the risk for?
Primary antiphospholipid antibody syndrome
Pattern of analytes for twins?
Everything is high (nearly doubled)
Confined placental trisomy 16 analytes?
High HCG, high AFP