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Trisomy 21 in newborn infants: chest radiographic diagnosis
D K Edwards1, C C Berry, S W Hilton
1Department of Radiology, University of California at San Diego, La Jolla 92103.
Insights
Chest X-rays can help identify infants with trisomy 21 (Down syndrome). The presence of specific skeletal features like multiple manubrial ossification centers, 11 rib pairs, and a bell-shaped chest increases the likelihood of trisomy 21.
Area of Science:
- Medical Imaging
- Genetics
- Pediatrics
Background:
- Trisomy 21 (Down syndrome) is a genetic disorder associated with characteristic physical features.
- Early identification of trisomy 21 is crucial for timely intervention and management.
- Certain radiographic findings in newborns have been anecdotally linked to trisomy 21.
Purpose of the Study:
- To evaluate the association between specific radiographic findings and trisomy 21 in neonates.
- To determine the diagnostic utility of multiple manubrial ossification centers, 11 rib pairs, and bell-shaped chest in identifying trisomy 21.
- To calculate the probability of trisomy 21 based on the presence and combination of these radiographic findings.
Main Methods:
- Retrospective review of chest radiographs from 30 infants with trisomy 21 and 881 unaffected infants.
- Radiographs were analyzed for the presence of multiple manubrial ossification centers, 11 rib pairs, and a bell-shaped chest.
- Statistical analysis was performed to calculate the prevalence of these findings and the conditional probability of trisomy 21.
Main Results:
- Multiple manubrial ossification centers were present in 80% of infants with trisomy 21 versus 9.6% of controls.
- 11 rib pairs were found in 33% of infants with trisomy 21 versus 5.2% of controls.
- A bell-shaped chest was observed in 80% of infants with trisomy 21 versus 23.6% of controls.
- The probability of trisomy 21 increased significantly with the presence of one, two, or all three findings, reaching 58.4% with all three.
Conclusions:
- Multiple manubrial ossification centers, 11 rib pairs, and a bell-shaped chest are significantly more common in infants with trisomy 21.
- These radiographic findings can aid in the early suspicion and diagnosis of trisomy 21 in newborns.
- The combination of these findings substantially increases the predictive value for trisomy 21.
Abstract:
Chest radiographs of 30 infants with trisomy 21 and 881 unaffected infants were evaluated for the following findings common in trisomy 21: multiple manubrial ossification centers, 11 rib pairs, and a bell-shaped chest. Radiographs were obtained in the first 48 hours of life. Of the 881 unaffected infants, 85 (9.6%) exhibited multiple manubrial ossification centers; 46 (5.2%), 11 rib pairs; and 208 (23.6%), bell-shaped chest. Of the 30 infants with trisomy 21, 24 (80%) exhibited multiple manubrial ossification centers; ten (33%), 11 rib pairs; and 24 (80%), bell-shaped chest. The probability of trisomy 21 in routinely radiographed newborn infants is 0.05% when none of the three findings is present, 1.6% with multiple manubrial ossification centers alone, 0.2% with 11 rib pairs alone, and 0.7% with bell-shaped chest alone. The probability of trisomy 21 increases in patients with two findings and reaches 58.4% in patients with all three findings.