Nuchal Translucency

Ultrasound scanning guidelines

Nuchal Translucency Performed on patients as part of a 1st trimester screening programme Scan transabdominally initially, transvaginal scanning can be considered if there is difficulty in obtaining correct fetal position Fetus must be between 45mm and 82mm Crown Rump Length in size Imaging Criteria: Minimum criteria for selecting a NT measurement as adequate include: Fetus must be supine Measurement must be in a true sagittal section, landmarks are fetal face and heart Magnification so that head and chest take up 75% of the image Head in neutral position (mild flexion is acceptable but the chin must not be on the chest wall) Ideal but not essential A measurement with the fetus lifted off the amnion Fetal head in true neutral position Measurement: Measure the widest point perpendicular to the skinline If the cord is around the neck the measurement can be falsely increased, in this case take the average of the measurement above and below the cord Record the largest measurement from the best image Documentation: Long and trans image of the uterus Crown rump length Fetal heart Nuchal translucency measurement x2 meeting the above criteria

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