Printer Friendly

Missing fetal nasal bone refines trisomy 21 Dx. (Ultrasound Screening at 11-14 Weeks).

Ultrasound screening for the absence of a fetal nasal bone at 11-14 weeks' gestation is a new technique that offers promise for further refining the prenatal diagnosis of trisomy 21, according to Dr. Simona Cicero of King's College Hospital Medical School, London, and her associates.

The researchers performed ultrasound evaluation on 701 fetuses who were considered to be at risk for the chromosomal abnormality because of advanced maternal age and a previous finding of nuchal translucency

Among 59 fetuses later determined by chorionic villus sampling and fetal karyotyping to have trisomy 21, the nasal bone was noted to be absent on ultrasound in 43 (73%). In comparison, among the 603 normal-karyotype fetuses, the nasal bone was absent in only 3 (0.5%).

Screening for trisomy 21 by maternal age and ultrasound detection of nuchal translucency has been estimated to have a sensitivity of 75% and a false-positive rate of 5%. The sensitivity could rise to 85% and the false-positive rate could decrease to about 1% if ultrasound screening also detected the absence of the fetal nasal bone.

Furthermore, "a sensitivity of more than 90% could probably be achieved by the comb nation of nasal bone, nuchal translucency thickness, and firs-trimester maternal serum biochemistry," hey wrote (Lancet 358[9294]:1665-67, 2001).

An editorial accompanying he article points out the "compelling" advantages of first-trimester, noninvasive screening using these techniques, including the possibility for "less traumatic" abortion for some but "earlier r assurance" for most (Lancet 35/[9294]1658-59,2001).
COPYRIGHT 2002 International Medical News Group
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2002 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Walsh, Nancy
Publication:OB GYN News
Date:Feb 1, 2002
Previous Article:Insurer's exit is sign of ailing malpractice market. (St. Paul Companies).
Next Article:Playing god? (Guest Editorial).

Related Articles
Ultrasound, Triple Screen Predict Trisomy 18 Risk.
Fetal nasal bone anomalies are highly predictive of down syndrome. (May Reduce Need for Invasive Testing).
US, blood test flag Down syndrome. (93% First-Trimester Detection Rate).
Short fetal nasal bone tied to 35% rise in down risk. (First Trimester).
Isolated anomaly may not warrant invasive testing: midtrimester scan.
Ethnicity, NT and down syndrome risk: consider crown-rump length.
Sensitivity of only 9%: no place for nasal bone evaluation by ultrasound in aneuploidy screening.
Fetal nasal bone length shown to be independent of maternal factors.
Point-of-care screening for chromosomal anomalies in the first trimester of pregnancy.

Terms of use | Privacy policy | Copyright © 2020 Farlex, Inc. | Feedback | For webmasters