NT/NB Scan: Importance, Procedure, and What to Expect


NT/NB scan, also known as Nuchal Translucency/Nasal Bone scan, is an important prenatal screening test that helps evaluate the likelihood of chromosomal abnormalities in foetuses. This non-invasive procedure offers important insights to soon-to-be parents and healthcare providers, assisting in early detection and well-informed decision-making. This guide will explore the importance of NT/NB scan, the process, its precision, and what soon-to-be parents can expect.

What is NT/NB Scan? 

This specialised ultrasound examination, known as the NT/NB scan, is typically conducted between the 11th and 14th weeks of pregnancy. The evaluation focuses on two important indicators: the thickness of the nuchal translucency (the clear space in the tissue at the back of the fetus’s neck) and the presence or absence of the foetal nasal bone. These measurements, in addition to maternal age and other factors, assist in assessing the likelihood of specific chromosomal abnormalities such as Down syndrome, Edwards syndrome, and Patau syndrome. 

Importance of NT/NB Scan:

  1. Early Detection: Identifying potential chromosomal abnormalities early in pregnancy with the NT/NB scan allows for timely interventions and decision-making, which is a significant advantage.
  2. Risk Assessment: Through evaluating the thickness of the nuchal translucency and the presence of the nasal bone, the scan offers important insights into the fetus’s risk of certain genetic conditions.
  3. Informed Decision-Making: With the results of the NT/NB scan, parents can make informed decisions about diagnostic testing, treatment options, and preparing for the care of a child with special needs.


The NT/NB scan is typically performed by a trained sonographer or obstetrician and involves the following steps:

  1. Ultrasound Examination: A detailed ultrasound examination is performed by the sonographer to measure the nuchal translucency and assess the presence of the nasal bone.
  2. Measurement and Assessment: With specialised equipment and software, we measure the thickness of the nuchal translucency and take note of the presence or absence of the nasal bone.
  3. Counseling: After the scan, parents-to-be are provided with counselling to go over the results, possible consequences, and next actions. 

Accuracy and Limitations: 

Although the NT/NB scan is a helpful screening tool, it’s essential to remember that it does not offer a conclusive diagnosis of chromosomal abnormalities. It provides an evaluation of the fetus’s risk level using specific markers. Additional testing like chorionic villus sampling (CVS) or amniocentesis may be suggested in certain situations to confirm or rule out a diagnosis.

What to Expect: 

Expectant parents going through an NT/NB scan may experience a range of emotions, such as excitement and nervousness. Here are a few important things to remember:

  1. Preparation: Usually, there is no need for any specific preparation before an NT/NB scan. It’s recommended to wear comfortable clothing and make sure to arrive on time for the appointment.
  2. Duration: Typically, the scan lasts for about 20 to 30 minutes, but the duration can vary based on factors like foetal position and cooperation.
  3. Follow-Up: If the scan results show any concerns, parents-to-be may be recommended for more tests or provided with extra support and guidance.


Ultimately, the NT/NB scan provides crucial prenatal screening information that gives valuable insights into the fetus’s health and development. Through evaluating important indicators like nuchal translucency thickness and nasal bone presence, this procedure assists in detecting the likelihood of chromosomal abnormalities at an early stage of pregnancy. Although the scan is not diagnostic, it is essential for providing valuable information to expectant parents and healthcare providers, enabling them to make well-informed decisions about pregnancy care and management. For those who are expecting or planning a pregnancy, it’s important to talk to your healthcare provider about the NT/NB scan to fully grasp its significance and how it may affect your specific circumstances. Stay informed, stay proactive, and confidently embrace the journey of parenthood.