Nuchal scan

Nuchal scan
Measurements of fetal nuchal translucency, nasal bone and facial angle according to the standards of the Fetal Medicine Foundation
SynonymsNuchal translucency
PurposeUsed to screen for abnormalities in a developing fetus
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A nuchal scan or nuchal translucency (NT) scan/procedure is a sonographic prenatal screening scan (ultrasound) to detect chromosomal abnormalities in a fetus, though altered extracellular matrix composition and limited lymphatic drainage can also be detected.[1]

Since chromosomal abnormalities can result in impaired cardiovascular development, a nuchal translucency scan is used as a screening, rather than diagnostic, tool for conditions such as Down syndrome, Patau syndrome, Edwards Syndrome, and non-genetic body-stalk anomaly.[2]

There are two distinct measurements: the size of the nuchal translucency and the thickness of the nuchal fold. Nuchal translucency size is typically assessed at the end of the first trimester, between 11 weeks 3 days and 13 weeks 6 days of pregnancy.[3] Nuchal fold thickness is measured towards the end of the second trimester. As nuchal translucency size increases, the chances of a chromosomal abnormality and mortality increase; 65% of the largest translucencies (>6.5mm) are due to chromosomal abnormality, while fatality is 19% at this size.[2] A nuchal scan may also help confirm both the accuracy of the pregnancy dates and the fetal viability.

  1. ^ Souka AP, Von Kaisenberg CS, Hyett JA, Sonek JD, Nicolaides KH (2005-04-06). "Increased nuchal translucency with normal karyotype". American Journal of Obstetrics and Gynecology. 192 (4): 1005–1021. doi:10.1016/j.ajog.2004.12.093. PMID 15846173.
  2. ^ a b Souka AP, Von Kaisenberg CS, Hyett JA, Sonek JD, Nicolaides KH (2005-04-06). "Increased nuchal translucency with normal karyotype". American Journal of Obstetrics and Gynecology. 192 (4): 1005–1021. doi:10.1016/j.ajog.2004.12.093. PMID 15846173.
  3. ^ Gomella, Tricia; Cunningham, M. (2013). Neonatology : management, procedures, on-call problems, diseases, and drugs. Gomella, Tricia Lacy, Cunningham, M. Douglas, Eyal, Fabien G. (7th ed.). New York. ISBN 9780071768016. OCLC 830349840.{{cite book}}: CS1 maint: location missing publisher (link)