Prenatal Diagnosis- Ultrasound scan, Amniocentesis & Chorionic villus sampling

Question 1

Define prenatal diagnosis.

Answer 1

Tests to detect congenital malformations and genetic disorders before birth.

Question 2

List three indications for prenatal diagnosis.

Answer 2

Advanced maternal age, family history of inherited conditions, exposure to teratogens.

Question 3

What genetic condition is strongly associated with increased fetal nuchal translucency thickness?

Answer 3

Down syndrome.

Question 4

At what gestational age is maternal serum alpha-fetoprotein (MSAFP) testing typically performed?

Answer 4

Between 15 and 20 weeks.

Question 5

Name two causes of high MSAFP levels.

Answer 5

Neural tube defect, multiple pregnancy.

Question 6

What is the detection rate of Down syndrome using the triple test?

Answer 6

0.75

Question 7

Fill in the blank: “The quadruple test has a detection rate of __________% for Down syndrome.”

Answer 7

0.79

Question 8

State two differences between amniocentesis and chorionic villus sampling (CVS).

Answer 8

CVS is earlier (10–12 weeks), amniocentesis is later (15–20 weeks); CVS has a higher miscarriage risk.

Question 9

What is the risk of miscarriage associated with amniocentesis?

Answer 9

0.5–1%.

Question 10

Fill in the blank: “CVS is typically performed between __________ and __________ weeks of gestation.”

Answer 10

10 and 12 weeks.

Question 11

What is the primary aim of prenatal diagnosis?

Answer 11

Provide accurate diagnosis and informed choice for parents.

Question 12

How is trisomy 18 identified in maternal serum testing?

Answer 12

Low MSAFP, unconjugated estriol, and beta-HCG levels.

Question 13

Describe the role of ultrasound guidance in invasive prenatal procedures.

Answer 13

Ensures precision and reduces complications.

Question 14

What is cordocentesis, and when is it typically performed?

Answer 14

Percutaneous umbilical blood sampling, done at 19 weeks.

Question 15

Fill in the blank: “Fibroblast culture from chorionic villus sampling takes __________ to __________ days.”

Answer 15

7 to 10 days.

Question 16

List two conditions where prenatal diagnosis through PUBS is indicated.

Answer 16

Hemoglobinopathies, rapid fetal karyotype.

Question 17

Why is counseling essential before and after prenatal diagnosis?

Answer 17

Provides psychological support and informed decision-making.

Question 18

Name three ethnic groups associated with sickle cell disease.

Answer 18

Africans, Afro-Caribbeans, Afro-Americans.

Question 19

What is the false-positive rate for the triple test in screening for Down syndrome?

Answer 19

8.5%.

Question 20

Fill in the blank: “Routine ultrasound in the third trimester detects __________ tract abnormalities.”

Answer 20

Urinary.

Question 21

Describe two potential outcomes of identifying anomalies in utero.

Answer 21

Parents can prepare for treatment or consider termination; manage birth in specialist units.

Question 22

Why is informed consent necessary before prenatal diagnosis?

Answer 22

Ensures ethical and legal compliance.

Question 23

What is the significance of the quadruple test in late bookers?

Answer 23

Allows testing up to 20 weeks for late pregnancies.

Question 24

List two major malformations detected in the second-trimester ultrasound.

Answer 24

Cardiac malformations, neural tube defects.

Question 25

Fill in the blank: “Cordocentesis has a miscarriage risk of __________%.”

Answer 25

0.01

Question 26

What is the primary purpose of maternal serum biochemistry testing?

Answer 26

Non-invasive screening for chromosomal anomalies.

Question 27

How does exposure to teratogens affect prenatal diagnosis considerations?

Answer 27

Increases risk of congenital malformations.

Question 28

What is the recommended gestational age for amniocentesis?

Answer 28

15–20 weeks.

Question 29

Fill in the blank: “Culture after amniocentesis takes __________ to __________ weeks for results.”

Answer 29

2 to 3 weeks.

Question 30

Why is prenatal diagnosis particularly important for parents with balanced chromosomal translocations?

Answer 30

Increases risk of chromosomal abnormalities in offspring.