Ultrasound in Pediatric Pneumonia is Predominantly Used as an Adjunct to Chest Radiography: A Retrospective Study

Pneumonia remains a top cause of morbidity and mortality in children worldwide. Timely diagnosis is key in improving outcomes. Historically, x-rays and computed tomography (CT) have been the primary imaging modalities for diagnosing pneumonia, despite associated costs, delays, and radiation exposure. Ultrasound (US) offers a low-cost, rapid, radiation-free alternative, with prior studies demonstrating high diagnostic accuracy for pneumonia in pediatric patients. However, real-world use of US in pediatric pneumonia remains poorly characterized. We sought to characterize the clinical context in which US is currently used for pediatric pneumonia.

We conducted a retrospective cohort study using TriNetX, a national de-identified electronic health record system. Pediatric patients 0-18 years with pneumonia (ICD-10 J12-J18) were identified, with the first diagnosis serving as the index event. Lung US exams were identified with lung and chest US procedure codes, excluding cardiac echocardiography. Imaging performed from one day prior to through the day of diagnosis was included to approximate emergency department workflows. Patients were stratified into US-only and US with chest radiography cohorts. Outcomes assessed within 15 days included receipt of antimicrobial therapy, hospital admission, intensive care unit (ICU) admission, and chest CT use, selected as markers of clinical severity and resource utilization.

Among 5,239 pediatric pneumonia encounters with US use, 560 (10.7%) underwent US only while 4,679 (89.3%) underwent US along with chest radiography. Compared with the US-only cohort, the US plus chest radiography cohort demonstrated higher rates of antimicrobial therapy (91.9% vs. 87.9%; RR 0.96), hospital admission (69.3% vs. 35.2%; RR 0.51), ICU admission (12.5% vs. 3.6%; RR 0.29), and chest CT use (21.6% vs. 5.0%; RR 0.23) (all p≤0.001). Mechanical ventilation and supplemental oxygen use were rare and could not be analyzed.

Despite strong evidence supporting US for pneumonia diagnosis, real-world practice shows US is primarily used as an adjunct to chest radiography rather than as a standalone diagnostic modality. US use is concentrated in higher-acuity clinical contexts marked by higher rates of admission, ICU care, and CT use, highlighting an evidence-practice gap and opportunities to optimize imaging pathways in pediatric emergency care.