European Journal of Cardiovascular Medicine

Pneumonia remains a leading cause of morbidity and mortality in children worldwide, particularly in low- and middle-income countries, where access to advanced diagnostic tools is often limited. The World Health Organization estimates that pneumonia accounts for approximately 14% of all deaths in children under five years of age, with the majority occurring in resource-constrained settings [1]. Early and accurate prediction of disease severity is crucial for guiding clinical decision-making, prioritizing resource allocation, and improving patient outcomes.

Traditionally, the assessment of paediatric pneumonia relies on a combination of clinical signs—such as fever, cough, and tachypnoea—and chest radiography. However, these clinical features are nonspecific and overlap with many other respiratory illnesses, making it challenging to distinguish severe cases that require advanced medical intervention [2]. Chest radiography, while commonly used to detect pulmonary abnormalities, is limited by repeated radiation exposure, variable image interpretation among clinicians, and a relatively low negative predictive value, which limits its role as a definitive diagnostic standard [3,4].

In recent years, lung ultrasound (LUS) has emerged as a promising, radiation-free imaging modality for the diagnosis of pneumonia in children. Multiple studies have demonstrated its high sensitivity and specificity compared to chest radiography, along with advantages such as portability, bedside applicability, and reduced inter-observer variability [5]. LUS offers the potential to provide real-time assessment of lung pathology, enabling clinicians to make timely, evidence-based decisions in both hospital and community healthcare settings.

Given this background, the present study addresses the research question: Can lung ultrasound serve as a reliable alternative to chest radiography in diagnosing community-acquired pneumonia and assessing its severity in children? By validating the diagnostic and prognostic value of LUS, this research seeks to simplify paediatric pneumonia diagnosis, reduce unnecessary antibiotic use, shorten hospital stays, and ultimately improve clinical outcomes.

Pneumonia remains a leading cause of morbidity and mortality in children worldwide, particularly in low- and middle-income countries, where access to advanced diagnostic tools is often limited. The World Health Organization estimates that pneumonia accounts for approximately 14% of all deaths in children under five years of age, with the majority occurring in resource-constrained settings [1]. Early and accurate prediction of disease severity is crucial for guiding clinical decision-making, prioritizing resource allocation, and improving patient outcomes.

Traditionally, the assessment of paediatric pneumonia relies on a combination of clinical signs—such as fever, cough, and tachypnoea—and chest radiography. However, these clinical features are nonspecific and overlap with many other respiratory illnesses, making it challenging to distinguish severe cases that require advanced medical intervention [2]. Chest radiography, while commonly used to detect pulmonary abnormalities, is limited by repeated radiation exposure, variable image interpretation among clinicians, and a relatively low negative predictive value, which limits its role as a definitive diagnostic standard [3,4].

In recent years, lung ultrasound (LUS) has emerged as a promising, radiation-free imaging modality for the diagnosis of pneumonia in children. Multiple studies have demonstrated its high sensitivity and specificity compared to chest radiography, along with advantages such as portability, bedside applicability, and reduced inter-observer variability [5]. LUS offers the potential to provide real-time assessment of lung pathology, enabling clinicians to make timely, evidence-based decisions in both hospital and community healthcare settings.

Given this background, the present study addresses the research question: Can lung ultrasound serve as a reliable alternative to chest radiography in diagnosing community-acquired pneumonia and assessing its severity in children? By validating the diagnostic and prognostic value of LUS, this research seeks to simplify paediatric pneumonia diagnosis, reduce unnecessary antibiotic use, shorten hospital stays, and ultimately improve clinical outcomes.

This prospective observational analytical study included 136 children, aged between 1 month and 14 years, diagnosed with community-acquired pneumonia (CAP) based on IMNCI criteria for children aged 1 month to 5 years and ICMR criteria for those older than 5 years. The study was conducted at the Department of Pediatrics, PGIMER & Capital Hospital, Bhubaneswar, from January 2023 to December 2024.

Figure 1 ROC showing correlation between consolidation in chest X-ray & Increased B-lines in lung ultrasound

The presence of increased B-lines on lung ultrasound demonstrated low sensitivity but high positive predictive value (PPV) for detecting consolidation on chest X-ray (Figure 1). The low negative predictive value (NPV) and low area under the curve (AUC) suggest poor ability to rule out disease. Therefore, increased B-lines alone should not be used as an isolated marker for detecting consolidation (Table 1).

Table 1 - Correlation between Consolidation on Chest X-ray and Increased Number of B-lines on Lung USG

Requiring the presence of both the shred sign and increased B-lines increased specificity and PPV, indicating that when both signs are present, it is highly likely that the patient has consolidation. However, this approach reduced sensitivity. The AUC (0.58) indicates poor diagnostic accuracy, and as the p-value was >0.05, the result was not statistically significant.

Figure 2. ROC curve showing correlation between Consolidation (Chest X-ray) and Shred Sign with Increased Number of B-lines on Lung USG

The details of the correlation between Consolidation on Chest X-ray and Shred Sign with Increased Number of B-lines on Lung USG is provided in the table no.2.

Table 2 - Correlation between Consolidation on Chest X-ray and Shred Sign with Increased Number of B-lines on Lung USG

Using either sign (shred sign or increased B-lines) improved sensitivity and maintained a high PPV for detecting consolidation. The p-value was <0.05, indicating statistical significance. The AUC of 0.80 suggests good diagnostic performance, with an 80% probability that the test correctly differentiates between patients with and without consolidation. The ROC curve demonstrated a favorable balance between sensitivity and specificity.

Figure 3 ROC showing Comparison of Consolidation (Chest X-ray) With Either Shred Sign or Increased No of B Lines (Lung USG)

The details of correlation between Consolidation on Chest X-ray and Either Shred Sign or Increased Number of B-lines on Lung USG is given in table 3

Table 3 - Correlation between Consolidation on Chest X-ray and Either Shred Sign or Increased Number of B-lines on Lung USG

For pleural effusion, lung ultrasound showed both high sensitivity and high specificity. The NPV of 100% indicates that when an anechoic collection was absent on lung ultrasound, there was a 100% probability that the patient did not have pleural effusion. The p-value was <0.05, showing a highly significant association between anechoic collection on lung ultrasound and pleural effusion on chest X-ray.

Figure 4. ROC curve showing correlation between Pleural Effusion (Chest X-ray) and Anechoic Collection on Lung USG

The details of correlation between Pleural Effusion on Chest X-ray and Anechoic Collection on Lung USG is provided in Table 4.

Table 4. Correlation between Pleural Effusion on Chest X-ray and Anechoic Collection on Lung USG

Lung ultrasound demonstrated a sensitivity of 79.3% and specificity of 80% for detecting lung pathology such as consolidation and pleural effusion, with a high PPV. A p-value of <0.05 indicated a strong statistical association between lung ultrasound and chest X-ray findings. The AUC of 0.80 reflects good overall diagnostic performance of lung ultrasound compared to chest X-ray in detecting lung pathology.

Figure 5: ROC showing Correlation Between Chest X-ray And Lung USG To Detect Lung Pathology

The details of the correlation between Chest X-ray and Lung USG to detect any lung pathology is provided in Table number 5

Table 5 showing Correlation between Chest X-ray and Lung USG to detect any lung pathology

In the present study, consolidation on chest X-ray was observed in a notable proportion of children diagnosed with community-acquired pneumonia (CAP). Right lower lobe involvement was detected in 28.57% of cases. This pattern is consistent with the findings of Jain et al. (2015) [6], who reported that the lower lobes are more frequently affected in paediatric pneumonia, likely due to gravitational factors and anatomical predispositions. Heterogeneous opacities were noted in 52.94% of cases, suggestive of patchy lung involvement often associated with viral or atypical pathogens. Similar observations have been reported by Bradley et al. (2011) [7].

The shred sign on lung ultrasound, which represents an irregular, fragmented pleural line due to subpleural consolidation, demonstrated moderate sensitivity but high specificity in our cohort. Overall, lung ultrasound showed a sensitivity of 79.3% and a specificity of 80% for detecting lung abnormalities. These findings are comparable to the meta-analysis by Pereda et al. (2015) [8], which reported pooled sensitivity and specificity of 96% and 93%, respectively, for diagnosing pneumonia in children. Elabbas et al. (2022) [9] similarly found lung ultrasound to be highly effective for detecting consolidation and pleural effusion, attributing its superior resolution to the thinner chest wall in children. Moreover, Bence et al. (2019) [10] reported that large subpleural consolidations were more indicative of bacterial aetiology, whereas smaller consolidations were suggestive of viral infection.

The following studies summarises sensitivity and specificity values reported in previous studies compared with our results.

Table 6 Reported diagnostic performance of lung ultrasound in previous studies

When either the shred sign or increased number of B-lines was used as the diagnostic criterion, sensitivity increased to 81.5%, with an AUC of 0.80. This aligns with the findings of Lorio et al. (2015) [10], who reported similar improvements in diagnostic accuracy when combining ultrasound features.

For pleural effusion, the presence of an anechoic collection on lung ultrasound achieved 100% sensitivity and 93.22% specificity in our study, confirming its superiority over chest radiography for detecting small effusions. Copetti and Cattarosi (2008) likewise demonstrated that lung ultrasound is more sensitive than chest X-ray for identifying pleural effusion in infants and young children.

Overall, the results of this study support the strong diagnostic value of lung ultrasound, particularly for identifying consolidation and pleural effusion in paediatric CAP. Its non-ionising nature, bedside applicability, and high diagnostic reliability suggest that lung ultrasound should be considered a first-line imaging modality for evaluating suspected pneumonia in children, especially in resource-limited settings where rapid and accurate diagnosis is crucial.

The present study demonstrates that lung ultrasonography (LUS) is a highly valuable diagnostic tool in the evaluation of pediatric pneumonia, with strong diagnostic agreement compared to chest radiography. Our findings show that the presence of increased B-lines on LUS correlates significantly with consolidation on chest X-ray, with moderate sensitivity and high specificity. The shred sign, although less sensitive when used alone, shows high specificity for pneumonia, supporting its role in confirming diagnosis. Using either shred sign or increased B-lines markedly improves sensitivity without compromising specificity, enhancing overall diagnostic accuracy. LUS demonstrated 100% sensitivity and high specificity for anechoic collections, clearly outperforming chest X-ray in detecting pleural effusions. In comparison with previous literature, our results align with global evidence that LUS offers high sensitivity and specificity, particularly for subpleural consolidation and pleural effusion. The portability, absence of radiation, and real-time capability of LUS make it an ideal first-line imaging modality for suspected pediatric pneumonia. Integration of LUS into routine pediatric respiratory assessment can improve diagnostic confidence, reduce reliance on radiography, and enable earlier, more targeted management of community-acquired pneumonia in children.