Down Syndrome Research Today is a free monthly online journal that collates and summarizes the latest research about Down Syndrome, including details on education, symptoms, treatment, information.

First-trimester nasal bone evaluation for aneuploidy in the general population.

Malone FD, Ball RH, Nyberg DA, Comstock CH, Saade G, Berkowitz RL, Dugoff L, Craigo SD, Carr SR, Wolfe HM, Tripp T, D'Alton ME,

Columbia University College of Physicians and Surgeons, New York, New York, USA. fdm9@columbia.edu

OBJECTIVE: To evaluate the role of fetal nasal bone imaging at 10 3/7 to 13 6/7 weeks as a screening tool for aneuploidy, in a prospective multicenter trial. METHODS: Unselected patients from the general population with viable singleton pregnancies at 10 3/7 to 13 6/7 weeks were recruited at 15 U.S. centers. All had screening with nuchal translucency (NT) ultrasound by specially trained sonographers. In the last 8 months of this trial, first trimester nasal bone evaluation was added to the screening protocol. Nasal bones were described as present, absent, or unable to determine. RESULTS: A total of 38,189 patients completed first trimester NT screening, of whom 6,324 also underwent nasal bone sonography. An acceptable nasal image was obtained in 4,801 cases (76%), with nasal bones described as present in 4,779 (99.5%), and absent in 22 (0.5%). There were 11 identified cases of trisomy-21 in the population of 6,324 patients. In 9 of the 11 cases (82%) the nasal bones were described as present, and 2 cases were described as unable to determine. The only other aneuploidies were 2 cases of trisomy-18, in 1 of which the nasal bones were described as absent, and in 1 present. Absence of nasal bones had sensitivity for aneuploidy of 7.7%, false-positive rate 0.3%, and positive predictive value 4.5%. CONCLUSION: First-trimester nasal bone evaluation was not a useful test for population screening for trisomy-21 and added little to first-trimester NT screening. The difficulty in performing first-trimester nasal bone sonography consistently, in the general population setting, will significantly limit the usefulness of this aneuploidy screening technique.

Published 1 December 2004 in Obstet Gynecol, 104(6): 1222-8.
Full-text of this article is available online (may require subscription).

© 2004-2008 Down Syndrome Research Today. All Rights Reserved.