The magnitude of increased risk associated with these findings varies by the population studied, the way information was obtained, and the number of criteria evaluated. Posterior nuchal thickening has been estimated to increase the risk of trisomy 21 by 11- to 17-fold, while shortened femur increased risks by 5-to 7.5-fold and pyelectasis increased risks by 1.5- to 1.9-fold. The best way to use these findings has not been fully validated.Sonography cannot be used to diagnose or exclude aneuploidy. It provides a noninvasive means by which to adjust the risk on the basis of a variety of sonographic features .Although the literature is studded with studies on the soft markers of aneuploidy, most are done on high-risk populations. To extrapolate the findings to low-risk populations is neither scientific nor logical. Prospective studies should be conducted to confirm the value of isolated “soft markers” in low-risk women.