It is a detailed ultrasound scan done at 11weeks-13weeks 6days of pregnancy. It is also known as Nuchal transluscency scan of first trimester anueploidy screening scan.
It is done mainly to screen your baby for any markers suggestiwe of genetic diseases. The chromosomal problems that are screened for are Down´s syndrome, Patau´s syndrome and Edward´s syndrome. In addition to the markers for chromosomal diseases, a screening anatomical assessment of the baby´s head, brain, face, hands and legs, spine, heart, bladder, placenta, cerwix etc are also done in accordance with the weeks of gestation and wisibility.
All pregnant women are at risk of carrying a baby with genetic or structural defects. It is preferable to get the scan done at the specific time period of pregnancy as many of the major structural defects and some of the genetic abnormalities in the baby can be ruled out to a great extent by this time.