NT NB Scan in Pregnancy: Why & When is It Done?

Pregnancy is a beautiful journey, but it also comes with many medical check-ups that ensure the health and safety of both mother and baby. One such important prenatal screening test is the NT NB Scan. Many expectant parents hear about this test for the first time during the first trimester and often wonder why it is necessary.

In this detailed guide, we will explain what is NT NB Scan in pregnancy, why do NT NB Scan in pregnancy, the right time to do it, how it is performed, its benefits, accuracy, risks, and frequently asked questions—so you feel confident and informed.

What is NT NB Scan in Pregnancy?

The NT NB Scan, also known as the Nuchal Translucency (NT) and Nasal Bone (NB) Scan, is a specialized ultrasound test performed during early pregnancy to assess the risk of certain chromosomal abnormalities in the fetus.

• NT (Nuchal Translucency): Measures the fluid-filled space at the back of the baby’s neck

• NB (Nasal Bone): Checks whether the baby’s nasal bone is present or absent

An increased NT thickness or absence of the nasal bone can indicate a higher risk of genetic conditions such as:

• Down Syndrome (Trisomy 21)

• Trisomy 18

• Trisomy 13

This scan does not confirm a disease but helps identify risk levels, guiding further testing if required.

Why Do NT NB Scan in Pregnancy?

Understanding why do NT NB Scan in pregnancy is crucial for every expecting mother.

Key Reasons for NT NB Scan:

1. Early Detection of Chromosomal Abnormalities
   The scan helps identify the risk of genetic disorders at an early stage.

2. Non-Invasive & Safe Screening
   Unlike invasive tests, NT NB Scan does not pose any risk to the baby or mother.

3. Guides Further Diagnostic Tests
   If the scan shows higher risk, doctors may recommend tests like NIPT, CVS, or Amniocentesis.

4. Provides Reassurance to Parents
   A normal scan result gives peace of mind during early pregnancy.

5. Helps in Better Pregnancy Planning
   Early detection allows timely medical decisions and expert counseling.

When is NT NB Scan Done in Pregnancy?

Timing plays a critical role in the accuracy of the NT NB Scan in pregnancy.

Ideal Time for NT NB Scan:

• Between 11 weeks to 13 weeks + 6 days

• Baby’s Crown Rump Length (CRL) should be 45 mm to 84 mm

❗ If the scan is done earlier or later than this window, results may not be accurate.

How is NT NB Scan Performed?

The NT NB Scan is a simple ultrasound procedure.

Procedure Steps:

• Performed using an abdominal ultrasound

• Takes around 20–30 minutes

• No injections or medicines involved

• Conducted in a radiology or diagnostic center

The radiologist measures:

• Thickness of nuchal translucency

• Presence or absence of nasal bone

• Fetal heart rate

• Basic fetal anatomy

Normal NT NB Scan Values

Higher NT values or absent nasal bone may indicate increased risk and require further evaluation.

NT NB Scan vs Double Marker Test

The NT NB Scan is often combined with the Double Marker Blood Test for better accuracy.

Combined Screening Includes:

• NT NB Scan

• Maternal blood test (PAPP-A & hCG)

• Mother’s age

This combination improves detection accuracy up to 85–90% for Down Syndrome.

Is NT NB Scan Mandatory?

No, the NT NB Scan is not mandatory, but it is highly recommended by gynecologists for all pregnant women—especially if:

• Mother’s age is above 30

• There is a family history of genetic disorders

• The previous pregnancy had chromosomal abnormalities

Consulting an experienced specialist is important. If you’re looking for expert pregnancy care, you can consult the Best Gynecologist in Karol Bagh for accurate guidance and prenatal screening support.

Benefits of NT NB Scan in Pregnancy

✔ Early risk assessment

✔ Safe and painless

✔ Helps avoid unnecessary invasive tests

✔ Provides clarity and reassurance

✔ Supports informed medical decisions

Are There Any Risks Involved?

The NT NB Scan is 100% safe and involves:

• No radiation

• No side effects

• No harm to fetus or mother

It is simply an advanced ultrasound examination.

What Happens If NT NB Scan Result is Abnormal?

An abnormal NT NB Scan does not mean the baby definitely has a disorder.

Next Steps May Include:

• NIPT (Non-Invasive Prenatal Testing)

• CVS (Chorionic Villus Sampling)

• Amniocentesis

• Genetic counseling

Your gynecologist will guide you based on your overall risk profile.

Who Should Definitely Get NT NB Scan?

• First-time mothers

• Women above 30–35 years

• IVF pregnancies

• History of miscarriage

• Family history of genetic conditions

For proper interpretation and next-step planning, always consult an experienced doctor like the Best Gynecologist in Karol Bagh, who specializes in prenatal diagnostics.

FAQs on NT NB Scan

1. What is NT NB Scan in pregnancy?

NT NB Scan is an ultrasound screening test done in early pregnancy to assess the risk of chromosomal abnormalities in the fetus.

2. Why do NT NB Scan in pregnancy?

It helps detect the risk of genetic disorders like Down Syndrome at an early stage without harming the baby.

3. Is NT NB Scan painful?

No, it is completely painless and non-invasive.

4. Can NT NB Scan detect all birth defects?

No, it only screens for chromosomal abnormalities, not all structural defects.

5. What if nasal bone is not visible?

Absence of nasal bone may indicate increased risk, but further tests are required for confirmation.

6. Is NT NB Scan compulsory?

It is not compulsory but highly recommended by doctors.

7. How accurate is NT NB Scan?

When combined with blood tests, it offers up to 90% accuracy in risk assessment.

Conclusion – NT NB Scan

The NT NB Scan in pregnancy is one of the most important first-trimester screening tests that helps ensure your baby’s healthy development. Understanding what is NT NB Scan in pregnancy and why do NT NB Scan in pregnancy empowers parents to make informed medical decisions early on.

Always remember—early screening leads to better care, timely intervention, and peace of mind. For expert prenatal care, accurate interpretation, and personalized guidance, consult a trusted specialist like the Best Gynecologist in Karol Bagh.