Detection of Trisomy 21 Using Nuchal Translucency Region in Ultrasonogram Images

Abstract

A chromosomal defect called Down syndrome, trisomy 21, causes cognitive delay and intellectual disabilities in fetuses. It is due to the additional copy of chromosome 21. The risk of Down syndrome increases with advanced maternal age. Down syndrome also develops Alzheimer s disease and increases the chance of leukaemia by 15 20 times. Each year one in every 800-1000 babies is born with Down syndrome. Thus, Down syndrome cannot be prevented but can be detected before the child is born using non-invasive prenatal methods. The most important marker for the early detection of Down syndrome is the thickness of the Nuchal translucency region. newlineNuchal translucency (NT) is a collection of fluid present at the back of the fetal neck during the early stages of gestation. Nuchal translucency appears to be a dark or anechogenic region the two white or echogenic regions. The measurement of Nuchal Translucency depends on the Crown Rump Length, which ranges from 45 - 84 millimetres from head to toe and is measured in the early weeks of gestation (11-14th weeks). Nuchal translucency attains its maximum thickness and generally disappears after the 14th week, and having a thickness of more than 3.5 mm increases the risk of Down syndrome newline