The use of genetic sonography to reduce the need for amniocentesis in women at high-risk for Down syndrome

Abstract

Much information has been published regarding the use of second-trimester genetic sonography for the prenatal detection of Down syndrome by examining multiple aneuploidy markers. Among high-risk mothers (advanced maternal age, abnormal triple screen, or both), while many undoubtedly will choose to have invasive testing as a first option, others will instead use the information derived from genetic sonography to obtain an adjusted risk for Down syndrome to guide their decision about genetic amniocentesis. Accordingly, it is imperative that these patients have accurate and detailed counseling regarding their degree of risk reduction when the genetic sonogram is normal. This article reviews the use of second trimester genetic sonography in reducing the need for amniocentesis in the high-risk patient. At our institution, in high-risk patients when the genetic ultrasound is normal, the amniocentesis rate has been only 3%. We have found that genetic sonography is a patient-driven service, and that the information obtained at the time of ultrasound is an important component of the patient's decision of whether or not to proceed with invasive testing.