Nuchal Translucency Differential Diagnosis

The nuchal translucency (NT) refers to the sonographic appearance of a collection of fluid under the skin behind the fetal neck on ultrasound examination. An increased NT thickness is associated with various fetal anomalies and genetic conditions. Here's a differential diagnosis for an increased nuchal translucency:

• Single Most Likely Diagnosis

  • Chromosomal Abnormalities (e.g., Down Syndrome, Trisomy 18, Trisomy 13): The most common cause of an increased nuchal translucency is a chromosomal abnormality, with Down Syndrome being the most prevalent. These conditions often have other associated ultrasound markers and can be confirmed with genetic testing.

• Other Likely Diagnoses

  • Congenital Heart Defects: Many congenital heart defects can lead to increased nuchal translucency due to altered hemodynamics and potential cardiac failure.
  • Genetic Syndromes (e.g., Noonan Syndrome, Turner Syndrome): Certain genetic syndromes can present with increased nuchal translucency among other features.
  • Intrauterine Growth Restriction (IUGR): Placental insufficiency leading to IUGR can cause increased nuchal translucency.

• Do Not Miss Diagnoses

  • Neck and Thoracic Abnormalities (e.g., Cystic Hygroma, Congenital Diaphragmatic Hernia): These conditions can significantly impact fetal and neonatal outcomes and may require specific prenatal and postnatal management.
  • Infections (e.g., Parvovirus B19, Toxoplasmosis): Certain infections can cause fetal hydrops and increased nuchal translucency, and their diagnosis can significantly alter management.

• Rare Diagnoses

  • Achondrogenesis and Other Skeletal Dysplasias: These rare conditions can cause increased nuchal translucency due to impaired bone growth and development.
  • Fetal Tumors (e.g., Teratoma): Rarely, fetal tumors can cause increased nuchal translucency, either directly or through secondary effects like cardiac failure.
  • Metabolic Disorders: Certain metabolic disorders can lead to fetal hydrops and increased nuchal translucency, though these are exceedingly rare.