Nasal bone evaluation in fetuses with Down syndrome during the second and third trimesters of pregnancy.
OBJECTIVE
This study examined the use of three-dimensional ultrasonography for evaluating the fetal nasal bone, as a sonographic marker of Down syndrome, during the second and early third trimesters of pregnancy.


METHODS
Forty fetuses, including 20 with trisomy 21, were scanned once by three-dimensional ultrasonography. A midline sagittal view of the facial profile was used to analyze the volume data. Independent examiners reviewed blinded and randomly allocated volume data sets for the nasal bone. Interobserver reliability was evaluated for the sonographic presence or absence of the nasal bone. Logistic regression determined the contribution of this parameter to the presence of Down syndrome.


RESULTS
Both examiners showed substantial agreement in scoring whether the nasal bone was visualized by three-dimensional ultrasonography (P < .001). They identified 40% to 45% of fetuses with abnormalities using the absence of the nasal bone as a sonographic marker. However, a substantial number of fetuses with abnormalities were also found to have a nasal bone present. The nasal bone was visualized in 80% to 90% of fetuses without abnormalities.


CONCLUSIONS
Three-dimensional ultrasonography can be used to evaluate the fetal nasal bone with substantial interobserver agreement during the second and early third trimesters of pregnancy. A nonvisualized nasal bone identified 40% to 45% of fetuses with Down syndrome in this study.
Lee
Wesley
W
Division of Fetal Imaging, Department of Obstetrics and Gynecology, William Beaumont Hospital, 3601 W Thirteen Mile Rd, Royal Oak, Ml 48073-6769, USA.
DeVore
Greggory R
GR
Comstock
Christine H
CH
Kalache
Karim D
KD
McNie
Beverley
B
Chaiworapongsa
Tinnakorn
T
Conoscenti
Giancarlo
G
Treadwell
Marjorie C
MC
Johnson
Anthony
A
Huang
Raywin
R
Romero
Roberto
R
D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D016015:Logistic Models; D009295:Nasal Bone / Q000000981:diagnostic imaging* / Q000196:embryology*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D016216:Ultrasonography, Prenatal