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


CONCLUSIONS
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.
Malone
Fergal D
FD
Columbia University College of Physicians and Surgeons, New York, New York, USA. fdm9@columbia.edu
Ball
Robert H
RH
Nyberg
David A
DA
Comstock
Christine H
CH
Saade
George
G
Berkowitz
Richard L
RL
Dugoff
Lorraine
L
Craigo
Sabrina D
SD
Carr
Stephen R
SR
Wolfe
Honor M
HM
Tripp
Tara
T
D'Alton
Mary E
ME
D000782:Aneuploidy; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D005333:Fetus / Q000002:abnormalities*; D006801:Humans; D015337:Multicenter Studies as Topic; D009295:Nasal Bone / Q000000981:diagnostic imaging* / Q000196:embryology* / Q000473:pathology; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal