1st Trimester Screening

Question 1

NT and risk of screening

Answer 1

• Below 1 MoM no pathology
• Pathological values 1.8- 2 MoM
• Thickness > 3 mm independent of MoM

Question 2

PAPP -A and risk of abnormality

Answer 2

• Fetuses with abnormalities have low PAPP-A

Question 3

hCG in screening

Answer 3

• Trisomy 21 has high hCG

- Trisomy 13 and 18 low hCG ( 2.5 MoM indicate possible pathology

Question 4

AFP in screening

Answer 4

• > 2.5 MoM indicate pathology like spina bifida or anencephaly
• Trisomy 21 and 18 have low values
• Trisomy 13 is slightly higher than normal

Question 5

Estradiol and screening

Answer 5

Trisomy 21 = low estradiol
Trisomy 18 = very low estradiol
Open neural tube defect = no change in estradiol level

Question 6

Inhibin A and screening

Answer 6

Values > 2.5 MoM may indicate Trisomy 21 or 13

High values in 2nd trimester: PIH, PET, IUGR, Fetal loss