NT Scan (Nuchal Translucency Scan): First-Trimester Chromosomal Screening
The NT Scan (Nuchal Translucency Scan) is a crucial first-trimester ultrasound screening test used to assess the risk of chromosomal abnormalities and certain structural defects in the developing fetus. It plays an important role in early prenatal care and informed pregnancy planning.
What Is an NT Scan?
An NT scan measures the clear fluid-filled space at the back of the baby’s neck, known as nuchal translucency. An increased thickness may indicate a higher risk of chromosomal conditions.
This scan helps screen for:
- Down syndrome (Trisomy 21)
- Trisomy 18 and Trisomy 13
- Certain congenital heart defects
- Early structural abnormalities
Why Is the NT Scan Important?
1. Early Risk Assessment
The NT scan allows early identification of babies at increased risk for genetic conditions.
2. Safe and Non-Invasive
It provides valuable information without harming the mother or baby.
3. Guides Further Testing
If results show increased risk, doctors may advise:
- Dual marker test
- NIPT (Non-Invasive Prenatal Testing)
- Diagnostic tests like CVS or amniocentesis (if required)
When Is an NT Scan Done?
| Gestational Age | Purpose |
|---|---|
| 11–13+6 weeks | Ideal time for NT measurement |
| Before 11 weeks | Not reliable |
| After 14 weeks | NT measurement not possible |
The scan must be done within this narrow window for accurate results.
How Is an NT Scan Performed?
-
Usually done via abdominal ultrasound
-
Sometimes transvaginal ultrasound may be required for clearer imaging
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The sonographer measures:
- Nuchal translucency thickness
- Nasal bone
- Fetal heart rate
- Basic fetal anatomy
What Is Considered Normal NT?
- Normal NT thickness: Up to 3.0 mm
- Higher values may indicate increased risk but do not confirm a diagnosis
Further testing is recommended only if risk appears elevated.
Is the NT Scan Safe?
Yes. NT scans use high-frequency sound waves and are completely safe for both mother and baby.
Who Should Get an NT Scan?
NT scan is recommended for:
- All pregnant women
- Women above 35 years of age
- Pregnancies conceived via IVF
- Family history of genetic disorders
- Previous pregnancy with chromosomal abnormalities
FAQs – NT Scan (Nuchal Translucency Scan)
What does an NT scan detect?
It screens for chromosomal abnormalities such as Down syndrome and certain structural defects.
Is NT scan compulsory?
It is not mandatory but strongly recommended for early risk assessment.
Does a high NT value mean the baby has a problem?
No. It only indicates increased risk. Further tests are needed for confirmation.
Is blood testing required with NT scan?
Yes. It is often combined with the dual marker blood test for accurate risk calculation.
Can NT scan detect gender?
No. Gender identification is not possible or permitted.
Is the scan painful?
No. It is painless and non-invasive.
What if I miss the NT scan window?
Alternative screening options like NIPT or anomaly scan may be advised.
Conclusion
The NT Scan is a vital first-trimester screening test that helps identify the risk of chromosomal abnormalities early in pregnancy. While it does not diagnose conditions, it empowers parents and doctors to plan appropriate next steps for a healthy pregnancy.
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Dr. Divya J G Dr. Divya J G is an exceptional and highly skilled Obstetrician & Gynaecologist, recognised for her expertise in maternity care, pregnancy scans, and advanced gynaecological and laparoscopic surgeries. She completed her MBBS at Mysore Medical College and Research Institute (MMCRI) and earned her MS in Obstetrics and Gynaecology from Bangalore Medical College. With over 13 years of clinical experience, Dr. Divya J G is known for her meticulous attention to detail and patient-centred approach. She carefully understands each woman’s unique health needs and delivers personalised, evidence-based care to ensure safe pregnancies, effective treatments, and optimal outcomes.
Dr. Divya J G has extensive experience in managing a wide range of obstetric and gynaecological cases, including comprehensive maternity care, gynaecological surgeries, infertility evaluation, and IVF-related treatments. Beyond her clinical expertise, she is known for building strong trust and confidence among her patients through compassionate, patient-centred care and clear communication. From fertility counselling and conception planning to pregnancy, delivery, and post-treatment recovery, Dr. Divya J G ensures that every woman feels well-informed, supported, and at ease throughout her medical journey. Her commitment to ethical practice and evidence-based treatment consistently contributes to positive patient experiences and successful outcomes.
