Nuchal Translucency (NT) Screening MCQs
Nuchal Translucency (NT) Screening–related MCQs along with correct answers and explanations — perfect for quick study or making notes.
Question 1. At what gestational age is NT screening ideally performed?
A) 8–10 weeks
B) 10–12 weeks
C) 11–13+6 weeks
D) 14–16 weeks
Answer: C) 11–13+6 weeks
Explanation: NT screening is most accurate when performed between 11 weeks and 13 weeks + 6 days of gestation. This timing ensures the fetus is large enough (CRL 45–84 mm) for accurate NT measurement and optimal risk calculation.
Question 2. Which of the following fetal structures is specifically measured in NT screening?
A) Amniotic fluid around the fetus
B) Fluid-filled space at the back of fetal neck
C) Size of the fetal abdomen
D) Crown-rump length alone
Answer: B) Fluid-filled space at the back of fetal neck
Explanation: NT measures the subcutaneous fluid at the back of the fetal neck. Increased NT thickness can indicate chromosomal abnormalities like Down syndrome, heart defects, or other syndromic associations.
Question 3. What is the normal range of fetal heart rate (FHR) during NT screening?
A) 80–100 bpm
B) 100–120 bpm
C) 120–160 bpm
D) 160–200 bpm
Answer: C) 120–160 bpm
Explanation: The normal fetal heart rate (FHR) during the first trimester typically ranges between 120–160 beats per minute. Deviations may indicate fetal distress or anomalies.
Question 4. Increased NT thickness is associated with which of the following conditions?
A) Fetal anemia
B) Chromosomal abnormalities
C) Renal agenesis
D) Neural tube defects
Answer: B) Chromosomal abnormalities
Explanation: An increased NT is mainly associated with chromosomal abnormalities such as trisomy 21 (Down syndrome), trisomy 18, trisomy 13, and can also be linked to congenital heart defects.
Question 5. Which ultrasound mode is most commonly used to measure NT?
A) A-mode
B) B-mode
C) M-mode
D) Doppler mode
Answer: B) B-mode
Explanation: B-mode ultrasound (brightness mode) provides two-dimensional images, which is standard for measuring nuchal translucency accurately.
Question 6. What is the significance of a nuchal translucency measurement greater than 3.5 mm?
A) Normal finding
B) Suggests fetal hypoxia
C) High risk of chromosomal and structural abnormalities
D) Predicts premature labor
Answer: C) High risk of chromosomal and structural abnormalities
Explanation: An NT measurement greater than 3.5 mm is considered significantly increased, and indicates a higher risk for chromosomal defects, congenital heart disease, and genetic syndromes.
Question 7. During NT measurement, the fetus should be in which position?
A) Hyperflexed
B) Hyperextended
C) Neutral position
D) Upside down
Answer: C) Neutral position
Explanation: For accurate NT measurement, the fetus should be in a neutral position — neither flexed nor hyperextended — to avoid overestimation or underestimation of NT thickness.
Question 8. Which maternal serum markers are combined with NT measurement for risk calculation in first-trimester screening?
A) β-hCG and PAPP-A
B) AFP and Inhibin-A
C) β-hCG and AFP
D) PAPP-A and Estriol
Answer: A) β-hCG and PAPP-A
Explanation: First-trimester combined screening includes NT measurement plus maternal serum markers β-hCG (beta-human chorionic gonadotropin) and PAPP-A (pregnancy-associated plasma protein A) to assess risk for chromosomal abnormalities.
Question 9. The Crown-Rump Length (CRL) range appropriate for NT measurement is:
A) 30–45 mm
B) 45–84 mm
C) 85–100 mm
D) 20–40 mm
Answer: B) 45–84 mm
Explanation: NT is only reliably measured when the Crown-Rump Length (CRL) is between 45 mm and 84 mm, corresponding roughly to 11–13+6 weeks gestation.
Question 10. What happens to nuchal translucency as gestational age increases beyond 14 weeks?
A) It remains the same
B) It decreases and becomes less useful
C) It continues to increase
D) It disappears completely
Answer: B) It decreases and becomes less useful
Explanation: Beyond 14 weeks, the nuchal translucency may reduce or become physiologically absorbed, making it less useful for screening purposes.
Question 11. What is the main reason NT increases in chromosomally abnormal fetuses?
A) Hypoxia-related edema
B) Renal obstruction
C) Amniotic fluid leakage
D) Maternal hypertension
Answer: A) Hypoxia-related edema
Explanation: In fetuses with chromosomal abnormalities, delayed or abnormal lymphatic drainage and cardiac dysfunction can cause subcutaneous fluid accumulation, leading to increased NT.
Question 12. Which structure should NOT be confused with nuchal translucency on ultrasound?
A) Amnion
B) Nasal bone
C) Spine
D) Umbilical cord
Answer: A) Amnion
Explanation: Care must be taken not to mistake the amnion (the fetal membrane) for the NT space. Proper imaging ensures that the lucency measured is indeed at the fetal neck and not between fetal membranes.
Question 13. Which chromosomal anomaly is most strongly associated with increased NT?
A) Trisomy 21
B) Trisomy 13
C) Trisomy 18
D) Turner syndrome
Answer: A) Trisomy 21
Explanation: Although increased NT can occur in various conditions, Down syndrome (Trisomy 21) has the strongest association with increased NT thickness.
Question 14. A fetus has an NT of 2.0 mm at 12 weeks gestation. This finding is:
A) Very abnormal
B) Normal
C) Highly suspicious of Down syndrome
D) Indicative of hydrops fetalis
Answer: B) Normal
Explanation: At 12 weeks, an NT of around 2.0 mm is within normal limits. Concern usually arises when NT exceeds 3.0–3.5 mm depending on gestational age.
Question 15. In addition to NT measurement, which fetal feature is often checked during first-trimester screening to enhance Down syndrome detection?
A) Amniotic fluid volume
B) Nasal bone
C) Abdominal circumference
D) Fetal limb length
Answer: B) Nasal bone
Explanation: Nasal bone assessment (presence or absence) enhances the detection rate for Down syndrome when combined with NT measurement and biochemical markers.
Question 16. Which guideline organization provides standardized protocols for NT screening?
A) ISUOG
B) WHO
C) ACR
D) FMF (Fetal Medicine Foundation)
Answer: D) FMF (Fetal Medicine Foundation)
Explanation: The Fetal Medicine Foundation (FMF) has set strict protocols and certification standards for performing NT measurements accurately and consistently worldwide.
Question 17. The ultrasound magnification for NT measurement should be:
A) Entire fetus visible
B) Fetus magnified so only the head and upper thorax fill the screen
C) Only fetal legs visible
D) Fetus and placenta visible together
Answer: B) Fetus magnified so only the head and upper thorax fill the screen
Explanation: For accurate NT measurement, the fetus should be magnified so that only the head, neck, and upper thorax are visible, ensuring precise caliper placement.
Question 18. When measuring NT, calipers should be placed:
A) Inner-to-inner borders of the NT space
B) Outer-to-outer borders
C) Middle of NT
D) Across the fetal skin
Answer: A) Inner-to-inner borders of the NT space
Explanation: Calipers should be placed at the inner edges of the nuchal space, ensuring no overestimation or underestimation.
Question 19. A thickened NT with normal karyotype most strongly suggests risk for which of the following?
A) Diabetes
B) Congenital heart defect
C) Limb deformities
D) Neural tube defect
Answer: B) Congenital heart defect
Explanation: If the fetus has a normal karyotype but increased NT, it indicates an increased risk for congenital cardiac defects, and a fetal echocardiogram is often recommended later.
Question 20. Which is a physiological factor that can falsely increase NT measurement?
A) Fetal movement
B) Maternal fasting state
C) Maternal anemia
D) Fetal gender
Answer: A) Fetal movement
Explanation: Fetal movements like flexion or hyperextension can temporarily alter NT measurements, so repeated images during fetal stillness are preferred.
Question 21. In NT screening, abnormal ductus venosus flow is most often associated with:
A) Neural tube defects
B) Cardiac anomalies and aneuploidy
C) Skeletal dysplasia
D) Polyhydramnios
Answer: B) Cardiac anomalies and aneuploidy
Explanation: Reversed or absent A-wave in ductus venosus flow is linked with chromosomal defects (especially Trisomy 21, 18, 13) and fetal heart defects.
Question 22. What pattern of tricuspid valve flow suggests an increased risk of Down syndrome during NT screening?
A) Increased forward flow
B) Normal regurgitation
C) Tricuspid regurgitation
D) Absent tricuspid flow
Answer: C) Tricuspid regurgitation
Explanation: Tricuspid regurgitation detected in the first trimester is associated with a higher risk of chromosomal anomalies, especially Trisomy 21.
Question 23. NT measurement should be abandoned and repeated later if fetal CRL is:
A) < 45 mm
B) Between 45–84 mm
C) > 90 mm
D) Between 40–50 mm
Answer: A) < 45 mm
Explanation: For reliable NT measurement, the crown-rump length must be between 45–84 mm. If CRL is <45 mm, wait and repeat scan.
Question 24. What is the recommended unit for NT measurement?
A) Inches
B) Pixels
C) Millimeters (mm)
D) Centimeters (cm)
Answer: C) Millimeters (mm)
Explanation: NT thickness is recorded in millimeters (mm) to ensure high precision.
Question 25. A fetus shows NT of 4.2 mm at 12 weeks gestation. What is the next best step?
A) No action needed
B) Schedule repeat NT after 2 weeks
C) Offer genetic counseling and possible invasive testing
D) Immediate delivery
Answer: C) Offer genetic counseling and possible invasive testing
Explanation: NT ≥ 3.5 mm significantly increases the risk of aneuploidy and structural anomalies. Counseling and possibly CVS (chorionic villus sampling) or amniocentesis are offered.
Question 26. An increased NT with normal karyotype warrants follow-up primarily for:
A) Fetal lung maturity
B) Fetal heart evaluation
C) Fetal brain evaluation
D) Placental location
Answer: B) Fetal heart evaluation
Explanation: Congenital heart disease (CHD) risk is higher even if karyotype is normal — so a fetal echocardiogram at 18–22 weeks is recommended.
Question 27. First trimester biochemical markers associated with NT screening include:
A) α-Fetoprotein and β-hCG
B) β-hCG and PAPP-A
C) Inhibin-A and Estriol
D) Cortisol and Progesterone
Answer: B) β-hCG and PAPP-A
Explanation: First trimester combined screening uses NT + free β-hCG + PAPP-A levels to assess risk of aneuploidy.
Question 28. An absent nasal bone combined with increased NT increases risk particularly for:
A) Turner syndrome
B) Down syndrome
C) Triploidy
D) Holoprosencephaly
Answer: B) Down syndrome
Explanation: Absent or hypoplastic nasal bone, when combined with increased NT, significantly increases the risk for Trisomy 21.
Question 29. At which gestational age is NT screening ideally performed?
A) 8–10 weeks
B) 10–11 weeks
C) 11–13+6 weeks
D) 14–16 weeks
Answer: C) 11–13+6 weeks
Explanation: NT screening is valid and reliable between 11 weeks 0 days and 13 weeks 6 days, matching CRL between 45–84 mm.
Question 30. In cases of cystic hygroma detected during NT screening, which syndrome is highly suspected?
A) Trisomy 21
B) Turner syndrome
C) Trisomy 18
D) Klinefelter syndrome
Answer: B) Turner syndrome
Explanation: Cystic hygroma (large septated fluid collections at the neck) is highly associated with Turner syndrome (45,X0).
Question 31. Which technique ensures the most accurate NT measurement?
A) Abdominal scan with small magnification
B) Transvaginal scan with full fetal body visible
C) Mid-sagittal section with head and thorax filling the screen
D) Oblique transverse section of fetal head
Answer: C) Mid-sagittal section with head and thorax filling the screen
Explanation: For proper NT measurement, you must obtain a true mid-sagittal section, zoomed so that only the head and upper thorax are visible.
Question 32. NT measurements should be taken during which fetal state?
A) During fetal breathing
B) During fetal movement
C) When the fetus is still and neutral neck position
D) When the fetus is flexed
Answer: C) When the fetus is still and neutral neck position
Explanation: Neck flexion or extension can artificially increase or decrease NT. Measurement must be done in neutral position, without fetal movements.
Question 33. If fetal neck is hyperextended, NT measurement will:
A) Appear smaller than actual
B) Appear larger than actual
C) Remain unchanged
D) Become invisible
Answer: B) Appear larger than actual
Explanation: Neck hyperextension exaggerates the NT thickness — leading to overestimation.
Question 34. In a fetus with increased NT but normal ductus venosus flow and nasal bone seen, the aneuploidy risk:
A) Remains very high
B) Decreases
C) Becomes zero
D) Increases for Triploidy only
Answer: B) Decreases
Explanation: Normal ductus venosus and present nasal bone reduce the risk even if NT is slightly increased.
Question 35. What factor does NOT affect the NT thickness?
A) Maternal BMI
B) Gestational age
C) Fetal movements
D) Fetal breathing
Answer: A) Maternal BMI
Explanation: Maternal factors like BMI do not affect NT; NT depends on fetal condition and sonographic technique.
Question 36. A thick NT but a normal karyotype raises the risk of which of the following anomalies most?
A) Neural tube defects
B) Congenital heart defects
C) Diaphragmatic hernia
D) Skeletal dysplasia
Answer: B) Congenital heart defects
Explanation: Even with normal chromosomes, thick NT is a warning for fetal heart defects.
Question 37. The minimum acceptable CRL (Crown-Rump Length) for NT screening is:
A) 30 mm
B) 45 mm
C) 60 mm
D) 84 mm
Answer: B) 45 mm
Explanation: NT screening should only be done if CRL is ≥45 mm.
Question 38. Increased NT in a first trimester scan may be found in which non-genetic conditions?
A) Fetal anemia
B) Cardiac failure
C) Amniotic band syndrome
D) All of the above
Answer: D) All of the above
Explanation: Various non-genetic causes like fetal anemia, cardiac failure, and amniotic bands can cause increased NT.
Question 39. Which is FALSE regarding NT measurement?
A) Measure at the widest point
B) Calipers should be placed on inner borders of nuchal space
C) Include the amnion while measuring
D) Fetus should be in a neutral position
Answer: C) Include the amnion while measuring
Explanation: You must NOT include the amnion — only the fluid space between skin and soft tissue is measured.
Question 40. An NT thickness >3.5 mm is categorized as:
A) Normal
B) Mild increase
C) Moderate increase
D) Abnormal / Cystic hygroma
Answer: D) Abnormal / Cystic hygroma
Explanation: NT >3.5 mm is considered abnormal and may suggest major chromosomal or structural anomalies.
Question 41. In twin pregnancies, NT measurement should be:
A) Done only in one twin
B) Averaged between both twins
C) Done separately for each twin
D) Not performed at all
Answer: C) Done separately for each twin
Explanation: Each twin’s NT is measured individually because their chromosomal and structural risks may differ.
Question 42. NT measurement is NOT reliable in which of the following?
A) Monoamniotic twins
B) Triplet pregnancies
C) Obese mothers
D) Vanishing twin scenario
Answer: D) Vanishing twin scenario
Explanation: A vanishing twin can release fetal DNA, altering screening results and making interpretation unreliable.
Question 43. Which chromosomal anomaly is most strongly associated with increased NT?
A) Trisomy 21
B) Trisomy 18
C) Turner syndrome
D) Patau syndrome
Answer: C) Turner syndrome
Explanation: Turner syndrome (45,XO) often shows very large NT thickness, sometimes even leading to cystic hygroma.
Question 44. Increased NT with normal nasal bone is most suggestive of:
A) Trisomy 13
B) Isolated cardiac defect
C) Trisomy 18
D) Neural tube defect
Answer: B) Isolated cardiac defect
Explanation: If the nasal bone is normal, but NT is increased, consider structural issues like cardiac defects first.
Question 45. What is the significance of a cystic hygroma found at NT scan?
A) Always benign
B) High risk of aneuploidy and structural defects
C) Only seen in infections
D) Resolves by itself always
Answer: B) High risk of aneuploidy and structural defects
Explanation: Cystic hygroma indicates very high risk for chromosomal abnormalities (like Turner’s) and heart problems.
Question 46. When measuring NT, which setting adjustment is important on ultrasound?
A) Increase gain
B) Decrease magnification
C) Turn off harmonics
D) Use highest frequency probe possible
Answer: D) Use highest frequency probe possible
Explanation: High frequency probes give better resolution, which is crucial for accurate NT measurements.
Question 47. In a case where NT is increased but all genetic tests are normal, what is the next best step?
A) Repeat NT at 20 weeks
B) Perform detailed fetal echocardiography
C) Ignore and reassure patient
D) Genetic counseling not needed
Answer: B) Perform detailed fetal echocardiography
Explanation: Fetal echo is important because cardiac defects are more common when NT is increased, even if genetics are normal.
Question 48. In the FMF (Fetal Medicine Foundation) risk model, which three parameters are combined with NT?
A) Maternal age, CRL, ductus venosus flow
B) Maternal age, free beta-hCG, PAPP-A
C) CRL, free beta-hCG, nasal bone
D) Maternal age, nasal bone, tricuspid regurgitation
Answer: B) Maternal age, free beta-hCG, PAPP-A
Explanation: The FMF risk model combines maternal age, free β-hCG, PAPP-A with NT to estimate Down syndrome risk.
Question 49. Which structural defect is NOT associated with increased NT?
A) Omphalocele
B) Diaphragmatic hernia
C) Duodenal atresia
D) Cardiac septal defect
Answer: C) Duodenal atresia
Explanation: NT increase is linked to heart defects, abdominal wall defects, and diaphragm hernias — not primarily duodenal atresia.
Question 50. Fetal edema on NT scan can occur due to:
A) Cardiac failure
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