Performed between 11 weeks 3 days and 13 weeks 6 days
Nuchal Translucency Ultrasound
Indications
- Patient desires genetic screening (provider may need to refer patient to specialty clinic)
- History of fetal anomalies
- Advanved Maternal Age (AMA)
Measurements
During the First Trimester Screening Ultrasound
- CRL - Crown-rump length (CRL must be between 45-84mm)
- FHR - Fetal Heart Rate
- NT - Nuchal Translucency: Fetus facing anteriorly with chin in neutral position, image zoomed in to include fetal head, neck, upper chest, nasal bone, palate and NT space separate from the amnion
- Normal NT measures <2.9mm or <95th %tile, however risk percentage is calculated with NT measurement and CRL
First Trimester Screening
Determines risk of fetal abnormality
- Risk calculated based on maternal age, NT measurement, and NIPT (non-invasive prenatal testing)
- NIPT is a maternal serum blood test that measures levels of Papp-A, hCG, and AFP - this can help indicate a risk for fetal Trisomy 13, Trisomy 18, Trisomy 21, fetal sex abnormality, and various syndromes