II. Definitions

  1. Nuchal Translucency
    1. Posterior fetal neck lucency by Ultrasound

III. Indications

  1. Early Antenatal Screening for Down Syndrome and birth defects

IV. Protocol

  1. Timing: 11-13 weeks gestation
  2. Technique
    1. Ultrasound used to measure the lucency of the posterior fetal neck
    2. Measurement requires additional special training and certification

V. Precautions

  1. Do not use Nuchal Translucency alone (combine with serum Aneuploidy Screening)
    1. Exception: Multiple Gestation pregnancies (serum testing is inaccurate)
  2. Abnormal Nuchal Translucency is associated with both Aneuploidy and structural defects
    1. Obtain detailed Fetal SurveyUltrasound at 18 to 22 weeks if abnormal Nuchal Translucency
    2. Obtain fetal Echocardiogram if abnormal Nuchal Translucency (per ACOG guidelines)

VI. Efficacy: Down Syndrome detection

VII. Differential Diagnosis: Increased Nuchal Translucency

  1. Down Syndrome and other Genetic Syndromes
  2. Major Congenital Heart Defect
  3. Great Vessel defect
  4. Fetal malformations, dysplasias, deformations and disruptions
  5. False Positives (Nuchal Translucency increases 15-20% per week in normal pregnancies)

Images: Related links to external sites (from Bing)

Related Studies