What are the components of the NT scan during pregnancy?

During pregnancy, NT scan, or nuchal translucency scan, is an important early prenatal screening method for detecting fetal chromosomal abnormalities and congenital heart defects. This examination is usually performed between 11-14 weeks of gestation and primarily includes the following components:

1. Measurement of fetal nuchal translucency thickness: This is the core component of the NT scan. Using a B-mode ultrasound device, the thickness of the fluid-filled space at the back of the fetal neck is measured to assess the risk of chromosomal abnormalities. This measurement is typically performed between 11-14 weeks of gestation.

2. Assessment of fetal nasal bone: This evaluates the presence and development of the nasal bone. Absence or underdevelopment of the nasal bone may be associated with certain chromosomal abnormalities.

3. Fetal heart rate monitoring: Using a fetal heart monitor, the fetal heartbeat is recorded to assess cardiac activity and detect any irregular rhythms. This is usually performed between 20-24 weeks of gestation.

4. Measurement of fetal growth parameters: Includes head circumference, abdominal circumference, and femur length, used to evaluate whether fetal growth is progressing as expected and to rule out growth restriction.

5. Assessment of amniotic fluid: Using ultrasound to measure amniotic fluid depth and amniotic fluid index, to evaluate whether the volume of amniotic fluid is sufficient to support fetal development.

6. Confirmation of placental position: Ensures the placenta is in the normal position to avoid complications such as placenta previa.