Prenatal Testing

Question 1

What is measured in FTS?

Answer 1

1. NT measurement

2. PAPP-A and beta hCG

Question 2

What conditions does FTS assess risk for?

Answer 2

T21 and T18

Question 3

When is FTS most accurate?

Answer 3

11-12 weeks, but usually performed anytime between 10w3d and 13w6d

Question 4

Tell me about PAPP-A: what is it produced by? When is it helpful to measure? Levels in T21 pregnancies? Levels in T18 pregnancies?

Answer 4

placenta, helpful only in the 1st trimester, significantly decreased in T21, less dramatically decreased in T18

Question 5

Tell me about hCG: What is is produced by? Levels in T21 pregnancies? Levels in T18 pregnancies? Pattern over time?

Answer 5

placenta, nearly doubled in T21, markedly decreased in T18, levels peak at 8 weeks and decrease steadily to 20 weeks when they plateau

Question 6

Analyte patterns in FTS for T21 and T18

Answer 6

T21: low papp-a, high hCG
T18: low papp-a, low hCG

Question 7

Detection rate of FTS for T21 and T18

Answer 7

~83% for T21
~90% for T18
(%5 false positive rate)

Question 8

Differential diagnoses for increased NT

Answer 8

• Aneuploidy (T21, Turner, etc.)
• Structural heart defect
• Genetic syndromes (i.e. Noonan)
• Adverse outcome

Question 9

What is measured in 2nd tri MSS?

Answer 9

1. AFP
2. hCG
3. uE3
4. Inhibin-A

Question 10

When is 2nd tri MSS performed?

Answer 10

14-22 weeks, most accurate 15-18 weeks

Question 11

What does 2nd tri MSS provide rise assessment for?

Answer 11

ONTDs, T21, T18

Question 12

What is the detection rate of 2nd tri MSS?

Answer 12

~80% for all conditions (with 5% FPR)

Question 13

Tell me about AFP: where is it produced? What is the detection rate for spina bifida? What is the detection rate for anencephaly? Pattern over time?

Answer 13

synthesized in the liver and excreted by the kidneys, detects ~80% of spina bifida, detects ~95% of anencephaly, increases steadily throughout pregnancy

Question 14

Tell me about uE3: what is it produced by? what pathway is it involved in? pattern over time?

Answer 14

placenta, cholesterol pathway, increases steadily throughout pregnancy

Question 15

Tell me about inhibin A: what is it produced by? pattern over time?

Answer 15

mostly by the placenta, remains constant from 10-25 weeks

Question 16

What factors are included in the algorithm for calculating a quad screen?

Answer 16

maternal age, weight, diabetes, race, number of fetuses, GA, previous child with T21

Question 17

Analyte patterns in quad screen for T21 and T18

Answer 17

T21: low AFP, high hCG, low uE3, high inhibin A
T18: All low

Question 18

Does FTS or quad screen have a higher detection rate for T21 and T18?

Answer 18

FTS (80-90%)

quad screen is only 70-80%

Question 19

MSS results indicating fetal demise

Answer 19

low hCG, low uE3, high AFP if recent but low AFP if not

Question 20

MSS results indicating triploidy

Answer 20

high AFP, high uE3, high hCG if diandry but low if digyny

Question 21

Conditions indicated by very low uE3 (2)

Answer 21

SLO and x-linked ichthyosis

Question 22

MSS results congenital finnish nephrosis

Answer 22

extremely high AFP (levels of 30+)

Question 23

Integrated screening steps and detection rate

Answer 23

1st trimester screening (NT, PAPP-A, hCG) –> 2nd trimester screening (AFP, uE3, inhibin A)

• 91-96% detection rate for T21 and T18
• results are withheld until both are complete
• eliminates option of CVS

Question 24

Indications for NIPT

Answer 24

AMA, abnormal serum screening, personal or fam hx of aneuploidy, abnormal ultrasound

Question 25

types of Herpes

Answer 25

• type 1 & type 2

- type 2 is genital form, which causes the problem

Question 26

Time of Herpes greatest risk

Answer 26

• primary maternal infection causes the greatest risk early in pregnancy and near term
• 1st trimester infection poses risk for CNS malformations
• no curable treatment

Question 27

High AFP differentials

Answer 27

• ONTDs
• abdominal wall defects
• finnish nephrosis (really high)
• adverse outcomes (