Ultrasound Poor Detector of Down Syndrome

A study has found that ultrasound is not an effective way to detect Down syndrome and may lead to the loss of more fetuses than cases of Down syndrome detected. The study was published in the Journal of the American Medical Association (JAMA. 2001;285:1044-1055; www.jama.com).

The researchers conducted a meta-analysis of data in related articles published between 1980 and 1999, focusing on the most common ultrasound markers used in screening for chromosomal abnormalities in the second trimester. They did not include studies of nuchal translucency in their review.

The results showed little accuracy for most of the ultrasound markers in detecting Down syndrome. If these markers dissuade high-risk women from having amniocentesis, say the researchers, fewer fetuses with Down syndrome will be detected. On the other hand, the ultrasound results may lead many women to have this interventional procedure who do not need it and thereby increase their risk of miscarriage. Furthermore, the false-positive rate for all the markers used together may approach 10%, producing needless anxiety in a large number of women.

The researchers concluded that ultrasound markers may produce more harm than benefit and that doctors should be cautious about using them to detect Down syndrome. The study was conducted by Rebecca Smith-Bindman, M.D., department of radiology, University of California at San Francisco (USA), and colleagues.




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