Absent nasal bone in the prenatal detection of trisomy 21 in a high-risk population
Department of Obstetrics, Gynecology and Reproductive Sciences, UMDNJ-Robert Wood Johnson Medical School/Saint Peter's University Hospital, New Brunswick, New Jersey 08903, USA. Obstetrics and Gynecology
(Impact Factor: 5.18).
06/2003; 101(5 Pt 1):905-8. DOI: 10.1016/S0029-7844(03)00170-4
To estimate the usefulness of absent nasal bone by ultrasound in the prenatal detection of second-trimester fetuses with trisomy 21.
This was a matched case-control study of sonograms from January 1, 1997 to April 30, 2002. Genetic sonograms and facial profile pictures of all fetuses that were subsequently proven to have trisomy 21 were reviewed (study group). A control group was identified during the same study period by using a 4-to-1 ratio matching for gestational age at the time of the ultrasound examination. The sensitivity and specificity of absent fetal nasal bone for trisomy 21 were determined, and overlap with other ultrasound aneuploidy markers was assessed.
Forty fetuses were identified with trisomy 21; in 29 (72.5%) a facial profile had been obtained. Of the 160 controls, 102 (64%) had facial profiles documented. Of the 29 fetuses with trisomy 21 with facial profile available, 12 had absent nasal bone (sensitivity 41%). None of the 102 control fetuses with facial profiles available had absent nasal bone (specificity 100%). The sensitivity of genetic ultrasound was increased from 83% (24 of 29) to 90% (26 of 29) by adding absent nasal bone to the other ultrasound aneuploidy markers.
In the second trimester of pregnancy, absent nasal bone has a sensitivity of 41% and a specificity of 100% in detecting fetal trisomy 21. Absent fetal nasal bone may be added to the list of ultrasound aneuploidy markers evaluated during a genetic sonogram.
Available from: Stefaan Berge
- "Absence and hypoplasia of the nasal bones have been proposed recently as important markers for the detection of trisomy 21 (Bunduki et al., 2003; Vintzileos et al., 2003; Zoppi et al., 2003). In order to be accurate, this finding must be assessed using a midsagittal section of the face (Bergé et al., 2001). "
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ABSTRACT: To determine the relationship between trisomies 13, 18, and 21 and craniofacial malformations detected by prenatal sonography.
During a 29-year period (1976 through 2004), prenatal sonographic findings of 69 fetuses with trisomy 13; 171 fetuses with trisomy 18; 302 fetuses with trisomy 21; and 17 fetuses with other trisomies were evaluated retrospectively, after fetal karyotype identification. Sonographic findings were compared with autopsy results in 209 patients (trisomy 13, n=39; trisomy 18, n=64; and trisomy 21, n=106).
For trisomy 13, cleft deformities were detected prenatally in 65.2%, and of the 39 cases with pathological information, 76.9% were found to have a cleft deformity. Ocular and orbital abnormalities were found in 28%. Malformations of the jaws and abnormal profiles were more frequently diagnosed postnatally than prenatally. For trisomy 18, abnormal profiles (41.5%) and ear abnormalities (5.3%) were the most noticeable ultrasound markers, next to abnormalities of the neurocranium (36.8%) and cranial bone configuration (21.6%). Dysmorphisms of the eye, ear, or nose were detected more frequently in autopsy cases. For trisomy 21, ultrasound showed an aberrant shape of the skull in 14.2% of fetuses. In general, the ocular-orbital and nasal abnormalities in fetuses with trisomy 18 or 21 were more evident in pathological examination than in prenatal ultrasound imaging.
Facial anomalies are common in the major trisomies, and their prenatal sonographic identification should be improved. The above-mentioned facial anomalies provide sufficient reason to consider performing cytogenic evaluation.
Available from: onlinelibrary.wiley.com
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ABSTRACT: Three-dimensional (3D) ultrasound of the fetal face with maximal mode rendering allows accurate visualization of the bony face and the distinct demonstration of both nasal bones in second-trimester fetuses. The aim of this study was to analyze the feasibility of assessing nasal bones spatially on prenatal ultrasound in second- and third-trimester fetuses with present and absent nasal bones.
The faces of 38 fetuses between 17 and 33 weeks' gestation were examined with 3D ultrasound and volumes were stored for offline evaluation. Eighteen fetuses had normal karyotype and an apparently normal nasal bone on 2D ultrasound; these were examined to standardize the 3D rendering technique. Twenty fetuses had trisomy 21.
In all 18 healthy fetuses both nasal bones could be demonstrated on 3D ultrasound. Nine of the 20 Down syndrome fetuses had a hypoplastic or absent nasal bone on two-dimensional ultrasound. On 3D ultrasound three of the nine had discrepant findings between left and right nasal bones with evidence of absence of one side, and hypoplasia (n = 2) or normal length (n = 1) of the other.
Unilateral absence or hypoplasia of nasal bones is an important and new observation in fetuses with Down syndrome. This differentiation is best demonstrated on 3D ultrasound with maximal mode rendering. This observation of unilaterality of findings could explain some discrepant findings on absence of nasal bones on two-dimensional ultrasound but their "presence" on lateral postmortem radiographs.
Available from: Luis F GONCALVES
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ABSTRACT: To determine the frequency and clinical significance of bilateral and unilateral hypoplastic nasal bones for the detection of Down syndrome by 3-dimensional ultrasonography.
Thirty-seven volumes of the fetal skull from fetuses with Down syndrome and 37 from fetuses without abnormalities were analyzed by 1 investigator blinded to fetal karyotype. The maximum intensity projection algorithm was used to reconstruct nasal bones. Ossification patterns were identified in anteroposterior and profile views. Sensitivity, false-positive rates (FPRs), and likelihood ratios (LRs) for detection of Down syndrome were calculated.
After exclusions (coronal acquisition [n = 11], hand in front of the face [n = 4], poor imaging [n = 2], incomplete follow-up [n = 2], and anomalies detected after delivery [n = 2]), 53 volumes were analyzed (26 fetuses with Down syndrome and 27 without abnormalities; median gestational age, 21 6/7 weeks [interquartile range, 19 6/7-25 2/7 weeks]). Rendered profile views revealed absent nasal bones in 18.9% (10 of 53) of the fetuses, and, among these, 90% (9 of 10) had Down syndrome (sensitivity, 34.6% [9 of 26]; FPR, 3.7% [1 of 27]; LR, 9.3 [95% confidence interval (CI), 1.3-68.7]). Three ossification patterns were identified in anteroposterior views: (1) normally developed, (2) delayed ossification, and (3) absent nasal bones. Sensitivity, FPR, and LR of absent nasal bones for detecting Down syndrome were 34.6% (9 of 26), 3.7% (1 of 27), and 9.0 (95% CI, 1.3-68.7), respectively. Sensitivity, FPR, and LR of delayed ossification for detecting Down syndrome were 42.3% (11 of 26), 22% (6 of 27), and 1.83 (95% CI, 0.8-4.4).
Absence of nasal bones is associated with the highest risk of Down syndrome. Delayed ossification is associated with a lower risk of Down syndrome than absent nasal bones. These ossification patterns may be indistinguishable on 2-dimensional ultrasonography.
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