Screening for aneuploidy: the genetic sonogram.
Over the past 10 years, the use of ultrasound in aneuploidy risk estimation has improved the way obstetrics is practiced. It allows patients to obtain more personalized risk assessment and has allowed many women a reasonable alternative to invasive testing. The addition of soft markers to the sonographic screening for aneuploidy has been extremely beneficial, especially when considered in combination with other ultrasound findings. The best estimate of risk seems to be achieved through the combined use of ultrasound, maternal serum screening, and maternal age. The literature supports the use of soft markers only when applied to the high-risk population, where the prevalence of aneuploidy is increased. If this information is applied to the low-risk populations, especially in isolation, the lower prevalence of aneuploidy makes the positive predictive value too low to be of any value in counseling patients. As with many screening tests it occasionally misses the diagnosis, and every patient needs to understand this potential shortcoming. It is a personal decision regarding their willingness to accept the risk of a missed diagnosis versus the risk of fetal loss from an invasive procedure. Although it is far from perfect, in the right hands and with appropriate counseling ultrasound is an excellent tool. This is such an important decision for women and their families, and it is worth the time it takes to explain the benefits and limitations of this test.
Stewart
Theresa L
TL
Maternal-Fetal Medicine/Genetics, Wilford Hall Medical Center, 2200 Bergquist Drive, Suite 1, 59 MDW/MMNO, Lackland AFB, TX 78248, USA. Theresa.Stewart@Lackland.AF.MIL
D000015:Abnormalities, Multiple / Q000235:genetics; D000782:Aneuploidy; D002882:Chromosomes, Human, Pair 13; D002887:Chromosomes, Human, Pair 18; D004314:Down Syndrome / Q000000981:diagnostic imaging / Q000235:genetics; D005260:Female; D005820:Genetic Testing; D006801:Humans; D011247:Pregnancy; D014314:Trisomy; D016216:Ultrasonography, Prenatal