Absent nasal bone in the prenatal detection of fetuses with trisomy 21 in a high-risk population.
ABSTRACT 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.
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ABSTRACT: To assess the incidence of aberrant right subclavian artery (ARSA) and other strong markers of Down syndrome and their correlation in a large population of second-trimester Down syndrome fetuses assessed in a tertiary referral center. Presence or absence of ARSA and other major ultrasound markers of Down syndrome was assessed in a population of 106 second-trimester Down syndrome fetuses referred to our unit for expert assessment and/or termination of pregnancy after karyotyping performed for positive first- or second-trimester screening or advanced maternal age or on maternal request. All cases in which the diagnosis of Down syndrome followed the ultrasound detection of major anomalies or soft markers were excluded from the study, as were all cases with a gestational age less than 14 + 0 weeks. We searched for the ARSA on the three vessels and trachea view using color or power Doppler. All fetuses underwent a thorough anatomic assessment and fetal echocardiography. The other Down syndrome markers assessed were: absent or hypoplastic nasal bone (NB-), defined as length < 5(th) centile; nuchal fold ≥ 5 mm; and mild pyelectasis (> 5 mm). In addition, the presence of major cardiac and extracardiac defects was recorded. A correlation analysis was then performed in order to investigate possible associations between markers and/or major anomalies. Postmortem or postnatal diagnostic confirmation was available in all cases. The mean (SD) gestational age at ultrasound assessment was 20.4 (4.1) weeks. The incidence of the various variables in the population of Down syndrome fetuses was: ARSA, 25%; NB-, 43%; nuchal fold ≥ 5 mm, 16%; pyelectasis, 17%; major heart defects, 41%; atrioventricular septal defect, 25%; and extracardiac anomaly, 24%. The presence of ARSA did not correlate with any of the other variables. The only positive correlations (P < 0.05) were between NB- and pyelectasis, and between cardiac and extracardiac defects. This represents the largest Down syndrome population assessed for ARSA. In this series, the incidence of ARSA was 25%, lower than previously reported in much smaller series. Its presence did not correlate with the presence of any other marker or major anomaly, including heart defects.Ultrasound in Obstetrics and Gynecology 07/2011; 39(2):191-5. · 3.56 Impact Factor
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ABSTRACT: Objective: A meta-analysis was performed to summarize the accumulated data on the screening performance of second-trimester sonographic markers for fetal trisomy 21. Methods: We conducted a literature search to identify 47 studies between 1995 and September 2012 that provided data on the incidence of sonographic markers in trisomy 21 and euploid fetuses at 14-24 weeks' gestation. Weighted independent estimations of detection rate, false positive rate, positive and negative likelihood ratios (LR) of markers were calculated. Results: The pooled estimates of positive and negative LR 5.85 (95% CI 5.04-6.80) and 0.80 (95% CI 0.75-0.86) for intracardiac echogenic focus, 25.78 (95% CI 12.85-51.73) and 0.94 (95% CI 0.91-0.98) for ventriculomegaly, 19.18 (95% CI 11.55-31.84) and 0.80 (95% CI 0.75-0.86) for increased nuchal fold, 10.82 (95% CI 8.43-13.72) and 0.90 (95% CI 0.86-0.94) for hyperechogenic bowel, 7.77 (95% CI 6.22-9.71) and 0.92 (95% CI 0.89-0.96) for mild hydronephrosis, 3.72 (95% CI 2.79-4.97) and 0.80 (95% CI 0.73-0.88) for short femur, 4.81 (95% CI 3.49-6.62) and 0.74 (95% CI 0.63-0.88) for short humerus, 21.48 (95% CI 11.48-40.19) and 0.71 (95% CI 0.57-0.88) for ARSA and 23.26 (95% CI 14.23-38.03) and 0.46 (95% CI 0.36-0.58) for absent or hypoplastic nasal bone. The combined negative LR, by multiplying the values of individual markers, was 0.13 (95% CI 0.05-0.29) when short femur but not short humerus was included and 0.12 (95% CI 0.06-0.29) when short humerus but not short femur was included. Conclusion: Presence of sonographic markers increases and absence decreases the risk for trisomy 21. In the case of most isolated markers there is only a small effect on modifying the pre-test odds for trisomy 21, but with ventriculomegaly, nuchal fold thickness and ARSA there is a 3-4 fold increase in risk and with hypoplastic nasal bone a 6-7 fold increase. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.Ultrasound in Obstetrics and Gynecology 12/2012; · 3.56 Impact Factor
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ABSTRACT: To systematically review the literature on diagnostic tests and the performance of nasal bone (NB) measurements obtained through a second trimester ultrasound scan to identify fetuses affected by Down Syndrome (DS). A search of screening tests for NB evaluation and measurements was carried out in the main international bibliographic databases (MEDLINE, EMBASE, CINAHL). Studies considered to be relevant were then subjected to a critical reading following CASP criteria (Critical Appraisal Skills Programme) by at least three independent observers. All data were extracted and tabulated by two independent investigators. A statistical synthesis of Sensitivity, Specificity, and Likelihood Ratios (meta-analysis) was performed with specific software (Meta-DiSc). From an initial list of 852 articles referring to ultrasound markers for Down syndrome, 207 relevant papers were selected. In the end, 18 studies were included in the quantitative synthesis. The pooled estimates of positive and negative LR were 31.75 (95% CI, 13.9-72.52) and 0.73 (95%CI, 0.66-0.8), respectively, for absent nasal bone and 12.82 (95% CI, 5.72-28.73) and 0.51 (95% CI, 0.37-0.69) for hypoplastic nasal bone. No relevant differences were found between the various means of defining nasal hypoplasia (MoM or percentiles). The BPD/NBL ratio shows somewhat higher sensitivity levels but lower specificity with a threshold effect. Results for nasal bone absence or hypoplasia show high specificity with acceptable sensitivity. Screening performance is higher with NB measurements as a function of MoM or percentiles rather than as the BPD/NBL ratio, with no differences between pregnant women classified into various risk groups for Down syndrome.Ultrasound in Obstetrics and Gynecology 10/2013; · 3.56 Impact Factor