The role of ultrasound in prenatal detection of chromosomal abnormalities

Abstract

Fetal aneuploidy is the leading cause of pregnancy loss. At least 95% of chromosomally abnormal conceptions are lost before term. Over the years, it has become common to offer genetic amniocentesis or chorionic villus sampling to all women who have increased risk of fetal chromosomal abnormalities. However, due to its invasive nature and associated risks, the practice of offering routine invasive testing to all high-risk pregnant women has been challenged. Owing to evolving improvement in high-quality sonographic imaging, it has become apparent that many chromosomal abnormalities that are associated with fetal structural abnormalities or aneuploidy markers are capable of being detected by ultrasound. Since fetuses with trisomies 18 and 13 have many major structural abnormalities, ultrasound has a high sensitivity for detecting them. On the other hand, over the years, investigators have been looking for sonographic markers to increase the detection rate for Down syndrome on prenatal sonography. This has le...