NT (Nuchal Translucency) SCAN

Nuchal scans or nuchal translucency (NT) scans are sonographic prenatal screening tests (ultrasound) that detect cardiovascular abnormalities in fetuses, though altered extracellular matrix composition and a restricted lymphatic system can also be detected. A nuchal translucency scan serves as a screening tool instead of a diagnostic tool for conditions such as Down syndrome, which can cause impaired cardiovascular development as a result of chromosomal abnormalities. 

NB (Nasal Bone) SCAN

The NB stands for the nasal bone. In a NT scan, the doctors look at the nuchal fold thickness and the existence of the nasal bone. The presence of an overly thick nuchal fold or the absence of the nasal bone can be indicators of Down syndrome. A NT scan is usually performed in conjunction with a blood test taken around the same time. A screening result will tell you the chances of having a baby with a chromosomal disorder.