Fetal Well-Being Assessment and Prenatal Diagnosis

Question 1

Which is the most accurate estimate of the gestational age …?

Answer 1

Fetal crown–rump length (measured in the first trimester)

Question 2

First trimester screening for aneuploidy includes …?

Answer 2

A combination of maternal age, pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin (β-hCG), and nuchal translucency (NT)

Question 3

Second trimester screening for aneuploidy includes..?

Answer 3

A combination of
maternal serum α-fetoprotein (MSAFP),
total or free β-hCG,
unconjugated estriol (uE3), and
inhibin A (quad test);

it is less sensitive than first trimester screening.

Question 4

The baby in-utero begins to experience the world through touch as early as……. weeks.

Answer 4

8 weeks ‘

Question 5

At <9 weeks of gestation, if the CRL and LMP dates differ by >5 days, then which is considered to be accurate ..?

Answer 5

ultrasound is considered as the better estimate of GA

Question 6

After 14 weeks, measurement of the………. is used to estimate GA.

Answer 6

head circumference (HC) and femur length (FL)

Additional fetal measurements, including biparietal diameter (BPD), abdominal circumference (AC), fetal long bones (i.e., femur, humerus, ulna, and tibia), and transverse cerebellar diameter, may also assist in the estimation of fetal GA.

Question 7

First trimester aneuploidy screening is performed between. …….. weeks of pregnancy

Answer 7

11 and 13+6

Pregnancy-associated plasma protein-A (PAPP-A),
free β-human chorionic gonadotropin (β-hCG)
nuchal translucency (NT) on ultrasound

Question 8

Conditions associated with decrease levels of PAPP-A (<0.415 MOM) ..?

Answer 8

Besides aneuploidy

fetal growth restriction (FGR),
preterm labor,
gestational hypertension,
preeclampsia (PE), and
ectopic pregnancy

Question 9

PAPP-A is higher in…?

Answer 9

twin pregnancies

Question 10

What is assessment tool for NT scan ..?

Answer 10

Ultrasonographic assessment of the fluid collected at the nape of the fetal neck behind the cervical soft tissue, NT, is a sensitive marker for aneuploidy

Question 11

How to interpret the NT measurement ..?

Answer 11

It should be measured for a CRL between 45 and 84 mm

NT above the 95th centile for a particular CRL (2.1 mm for a CRL of 45 mm, and 2.7 mm for a CRL of 84 mm) is associated with an increased risk of aneuploidy

Question 12

Risk of other anomalies in the fetus with an increased NT includes…?

Answer 12

cardiac defects
lymphatic defects
single-gene defects,
central nervous system (CNS) defects, and
skeletal and abdominal wall defects

Question 13

Ultrasound for NT is best performed at what weeks of gestation..?

Answer 13

at 11 to 13+6

Question 14

Other ultrasound findings in the first trimester fetus that may be associated with trisomy include…?

Answer 14

absent or hypoplastic nasal bone,
abnormal ductus venosus (DV) blood flow, and
triscuspid regurgitation.

Question 15

What is OSCAR ….?

Answer 15

one-stop clinic for assessment of risk (OSCAR)—

It is practiced in centers where biochemistry is performed by 11 weeks and scan at 11 to 12 weeks and risk assessed after scan.
CVS is offered on the same day if risk is more than 1 in 100

Question 16

What is Quadruple panel (quad test) …?

Answer 16

serum α-fetoprotein (MSAFP),
hCG (free β or total),
unconjugated estriol (uE3), and
inhibin A

Question 17

In a pregnancy (fetus) with trisomy 21 quad test ….?

Answer 17

hCG (free β or total) and inhibin A levels are high,

MSAFP and uE3 levels are low

Question 18

Trisomy 18 quad test ….?

Answer 18

Low levels of all serum biochemical markers

Question 19

What percentage of fetuses with trisomy 21 will have a “positive” quadruple screen…?

Answer 19

80%

Question 20

About MSAFP ..?

Answer 20

It is best measured between 15 and 22 weeks.

α-Fetoprotein (AFP) is secreted by the fetus and is present in the amniotic fluid and maternal serum

MSAFP elevated above 2.5 multiples of median (MOM) for the GA occurs in 70% to 85% of fetuses with open spina bifida and 95% of fetuses with anencephaly

Question 21

USG signs in NTD ..?

Answer 21

Ultrasonography intracranial signs such as

changes in the head shape (lemon sign) or

deformation of the cerebellum (banana sign)

Question 22

Which approach achieves the highest detection rate of trisomy 21 (97%) at a low screen-positive rate (2%)..?

Answer 22

Integrated screening.

It involves a first trimester ultrasound and maternal serum screening in both the first and second trimesters.

Question 23

What is Sequential screening …?

Answer 23

Results indicating a high risk of trisomy 21 in the first trimester are declared, but the entire population is screened in the second trimester (stepwise sequential)

Question 24

Stepwise screening ….?

Answer 24

First trimester screen, then quad screen for all

Question 25

Contingent screening …?

Answer 25

First trimester screen, then quad screen only for intermediate/high risk

Question 26

What is TIFFA …?

Answer 26

Mid-trimester (targeted imaging for fetal anomalies (TIFFA)] scan, between 18 and 22 weeks, has traditionally enabled imaging to screen and detect fetal structural anomalies.

Question 27

Fetal echocardiogram (ECHO) for prenatal diagnosis basic views …?

Answer 27

Initially, fetal echocardiography included only

a four-chamber view (basic cardiac echocardiographic examination [BCEE]) of the heart, and

outflow tract view (OTV) and

three-vessel trachea view (3VTV)

Question 28

Indications of fetal echocardiography could be as follows: Fetal—

Answer 28

suspected CHD on screening ultrasonography,

fetal chromosomal anomaly—fetal extracardiac anatomic anomaly,

fetal cardiac arrhythmia - persistent bradycardia or tachycardia, irregular rhythm, and

nonimmune hydrops fetalis

Question 29

Indications of fetal echocardiography could be as follows: Maternal ..?

Answer 29

maternal metabolic diseases, e.g., overt diabetes, phenylketonuria, systemic lupus erythematosus, maternal exposure to alcohol, and intake of cardiac teratogenic medications

Question 30

Which abnormalities that may be missed by fetal echocardiography ….?

Answer 30

Coarctation of aorta,
small ventricular and atrial septal defects,
partial anomalous pulmonary venous return, and
mild aortic or pulmonary stenosis

Question 31

Indication for Cell-free fetal DNA screening for aneuploidy….?

Answer 31

currently is recommended only for women at a high risk for aneuploidy—women who are >35 years old, have a history of a fetus or newborn with aneuploidy, are carriers of a balanced translocation, or have a positive traditional screening test

Question 32

Fetal cell fraction is a major determinant of a good NIPT—a minimum of what percentage is needed..?

Answer 32

4.5%

Question 33

possible sources of false-positive results NIPT ..?

Answer 33

Maternal chromosomal abnormalities or
malignancy

vanishing twins or
confined placental mosaicism

Question 34

Failed NIPT can occur in……?

Answer 34

maternal obesity and very early GA.

Question 35

chorion villus sampling (CVS)..?

Answer 35

Performed at or after 11 weeks of gestation (till 13+6 weeks),

CVS provides the earliest possible confirmation of a genetically abnormal fetus through analysis of trophoblast cells

Question 36

CVS, if performed before 10 weeks of gestation, can be associated with an increased risk of which anamoly..?

Answer 36

fetal limb reduction defects and oromandibular malformations

Question 37

About Diagnostic study - amniocentesis ..?

Answer 37

Amniotic fluid around the fetus is aspirated through a needle guided by ultrasound.

The removed amniotic fluid (~20 mL) is replaced by the fetus rapidly within 24 hours

Question 38

Amniocentesis can technically be performed as early as…?

Answer 38

10 to 14 weeks of gestation

although early amniocentesis (<13 weeks) is associated with a pregnancy loss rate of 1% to 2% and an increased incidence of clubfoot

Question 39

Loss of the pregnancy following an ultrasonography-guided second trimester amniocentesis (16 to 20 weeks) is lower..?

Answer 39

at 0.5% to 1.0% in most centers.

Question 40

Enzymatic/biochemical analysis of amniotic fluid…?

Answer 40

Increased levels of AFP along with the presence of AChE identify NTDs with >98% sensitivity

Assessment of fetal lung maturity by LS ratio (lecithin/sphingomyelin ratio)

Question 41

percutaneous umbilical blood sampling (PUBS) risk…?

Answer 41

PUBS is associated with a 1% to 2% risk of fetal loss and 5% risk of preterm delivery.

Question 42

fetal bradycardia, defined as an FHR

Answer 42

<110 bpm

Question 43

Feral tachycardia, defined as an FHR…?

Answer 43

> 160 bpm

Question 44

Fetal dysrhythmias are typically associated with FHR……?

Answer 44

> 200 bpm

Question 45

Normal Baseline variability of FHR ….?

Answer 45

beat to beat by approximately 5 to 25 bpm

Question 46

Accelerations of the FHR in response to …?

Answer 46

movements

Question 47

Early decelerations features …?

Answer 47

Early decelerations are symmetric in shape and closely mirror uterine contractions in time of onset, nadir, duration, and termination.

They are benign and maintain good baseline variability

Question 48

Late decelerations features …?

Answer 48

Late decelerations are decreases in the FHR that occur “late” in relation to uterine contractions. The onset, nadir, and recovery of the deceleration occur after the beginning, peak, and end of the contraction, respectively.

Question 49

Late decelerations are the result of …..?

Answer 49

uteroplacental insufficiency and possible fetal hypoxia

Question 50

As the uteroplacental insufficiency/ hypoxia worsens, what happens to decelerations ..?

Answer 50

(i) baseline variability will be reduced and then lost,

(ii) decelerations will last longer,

(iii) they will begin sooner following the onset of a contraction,

(iv) they will take longer to return to baseline, and

(v) the rate to which the fetal heart slows will be lower

Question 51

Variable decelerations features ……?

Answer 51

vary in their shape and have no specific relationship with contractions.

Usually, they result from fetal umbilical cord compression.