NT measuring mathod

Measuring mathod

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• Gestational Age: Ideally between 11 weeks 0 days to 13 weeks 6 days.
• Crown-Rump Length (CRL): Between 45 mm and 84 mm.
• Fetal Position: Midsagittal plane of the fetus with neutral head position—not flexed or hyperextended.
• Magnification: The fetal head and thorax should fill at least 75% of the image.
• Caliper Placement: Measure the maximum lucency at the back of the fetal neck—inner-to-inner margins of the nuchal space.
• Image Settings: High contrast and clear resolution. Amniotic membrane should be distinguishable from the NT space.
• Number of Measurements: Take at least 3 measurements and record the highest consistent one.
• Exclude: Do not include the amnion or fetal skin in the measurement.

Step-1: Preparation for the Scan No special preparation is needed, but a full bladder may help improve image clarity. The scan is typically abdominal, but in some cases, a transvaginal ultrasound may be used for better visualization.
Step-2: Performing the Ultrasound The sonographer places an ultrasound probe on your abdomen (or inserts a transvaginal probe if necessary). The baby is positioned in a mid-sagittal view (side profile). The image is magnified to ensure accurate measurement.
Step-3: Measuring the Nuchal Translucency The sonographer identifies the fluid-filled space at the back of the baby’s neck. Using calipers, the maximum thickness of this translucent (fluid-filled) area is measured. The measurement is taken three times, and the largest reading is recorded for accuracy.
Step-4: Interpreting the NT Measurement Normal NT thickness: Typically less than 3.0 mm. Increased NT thickness: Over 3.5 mm may indicate a higher risk of chromosomal abnormalities like Down syndrome (Trisomy 21), Trisomy 18, or congenital heart defects.
Next Step: NT measurement is combined with maternal age, blood test results (PAPP-A, β-hCG), and other factors to estimate the risk of chromosomal abnormalities. This combined screening helps determine if further diagnostic testing (e.g., NIPT, CVS, or amniocentesis) is recommended. If the NT is increased, further testing (such as NIPT, CVS, or amniocentesis) may be recommended.

What If NT is High?

If the Nuchal Translucency (NT) measurement is higher than normal (typically >3.5 mm), it does not mean the baby definitely has a problem, but it may indicate an increased risk for certain conditions.
Possible Implications of High NT
1. Chromosomal Abnormalities

• Down syndrome (Trisomy 21)
• Edwards syndrome (Trisomy 18)
• Patau syndrome (Trisomy 13)
• Turner syndrome (Monosomy X)

2. Structural Anomalies

• Congenital heart defects (most common)
• Diaphragmatic hernia
• Skeletal dysplasias

3. Genetic Syndromes

• Noonan syndrome
• Other single-gene disorders

4. Poor Pregnancy Outcome (in some cases)

• Miscarriage
• Fetal death
• Intrauterine growth restriction (IUGR)

Steps After High NT

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1. Chromosomal Abnormalities

• Down syndrome (Trisomy 21)Edwards syndrome (Trisomy 18)
1. Detailed Ultrasound (including fetal anatomy and heart evaluation)
2. First-Trimester Combined Screening (NT + PAPP-A + free β-hCG)
3. Non-invasive Prenatal Testing (NIPT) – analyzes fetal DNA in maternal blood
4. Diagnostic Testing (if indicated)

• Chorionic Villus Sampling (CVS) at 11–13 weeks
• Amniocentesis after 15 weeks