Genetic Sonography: Entrez Pub Med

1: J Ultrasound Med. 2004 Dec;23(12):1619-27. Related Articles, Links: Phenotypic characteristics of absent and hypoplastic nasal bones in fetuses with Down syndrome: description by 3-dimensional ultrasonography and clinical significance.

Goncalves LF, Espinoza J, Lee W, Schoen ML, Devers P, Mazor M, Chaiworapongsa T, DeVore GR, Romero R.

Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA.

OBJECTIVE: To determine the frequency and clinical significance of bilateral and unilateral hypoplastic nasal bones for the detection of Down syndrome by 3-dimensional ultrasonography. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

PMID: 15557305 [PubMed - indexed for MEDLINE]

2: J Ultrasound Med. 2003 Jan;22(1):55-60. Related Articles, Links: Nasal bone evaluation in fetuses with Down syndrome during the second and third trimesters of pregnancy.

Lee W, DeVore GR, Comstock CH, Kalache KD, McNie B, Chaiworapongsa T, Conoscenti G, Treadwell MC, Johnson A, Huang R, Romero R.

Division of Fetal Imaging, Department of Obstetrics and Gynecology, William Beaumont Hospital, 3601 W Thirteen Mile Rd, Royal Oak, Ml 48073-6769, USA.

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.

PMID: 12523611 [PubMed - indexed for MEDLINE]