Prenatal Screening And Diagnosis

Question 1

Observations in BPP

Answer 1

Amniotic fluid volume
Fetal tone
Fetal movements
Fetal breathing 
NST
 Score: 8-10 reassuring 
            > 8 abnormal
            2-0: very concerning /fetal death

Question 2

First trimester screening

Answer 2

NT : should be below 3,5. Done between week 11-13+6 
B- hcg: 
PAPP-A
Nasal bone
Ductus venous flow
Tricuspid valve flow

Question 3

Triple test

Answer 3

Week 15-20
AFP
B hcg
Estriol

Trisomy 21: low AFP and estriol , elevated hcg

Trisomy 18: low hcg, AFP and estriol

Question 4

Quadruple test

Answer 4

Week 15-20
AFP
B hcg
Estriol 
Inhibin A

Question 5

Integrated screen

Answer 5

PAPP-A
NT
Quad screen 
This is the highest detection rate of DS
Can be used for screening of: tri 18, 21 and open NTD

Question 6

What risk ratio for DS is the mother offered invasive testing (CVS or amniocentesis)

Answer 6

1:270

Question 7

Screening for NTD

Answer 7

AFP in 2nd trimester: increased value
USG
From 15-22 weeks gestation

Question 8

Fetal biometry

Answer 8

Is used to assess growth or gestational age

1) biparietal diameter (measured at the level of thalamus and cavum septum pellicidum). Is the most accurate measurement of GA between 12th and 18th week.
2) head circumference
3) abdominal circumference
4) femur length

Question 9

When to perform genetic amniocentesis

Answer 9

From 15th to 20th week

Question 10

What can you detect in amniocentesis?

Answer 10

Check for NTD (AFP+ acetylcholinesterase), chromosomal abnormalities, Infections, bilirubin measurement (anaemia), fetal lung maturity (L/S ratio and PG)

Question 11

Risk of fetal loss in amniocentesis?

Answer 11

0,2-0,5%
1% of post procedure amniotic fluid leakage
1-2% Risk of preterm delivery if done in 3rd trimester

Question 12

When to perform fetal anatomy survey?

Answer 12

18th-20th week

Margin of error in GA: 7 days +-

Question 13

Chorionic villus sampling

At which week ?

Answer 13

10-12th week
Transcervical or transabdominal
Does NOT screen for oNTD

Question 14

LS ratio

Answer 14

> 2:1 = low risk of RDS

From amniocentesis

Question 15

USG dating

Answer 15

Best done between 8-12 week GA
Crown rump length: error 5 days
Most accurate dating
Change EDC to USG dates if > 1 week discrepancy from EDC based on LMP

Question 16

Risk of feral loss in CVS

Answer 16

1-2 %

Question 17

Increased MSAFP

Answer 17

Incorrect GA
Twins 
Fetal demise 
oNTD
Abdominal wall defect (omphalocele)

Question 18

Decreases MSAFP

Answer 18

Incorrect GA
GTN
Missed abortion
DS, Tri 18
Maternal diabetes

Question 19

NST

When is a test reactive ?

Answer 19

Reactive test: 2 accelerations of at least 15 beats amplitude of 15 seconds duration in a 20 min period

Question 20

NST

Most common cause of a nonreavtice NST?

Answer 20

Fetal inactivity or sleep

I’d test is nonreactive after 40 min a BPP or CST indicated