Ultrasonography: A Diagnostic Option to Radiography for Pediatric Pneumonia?

Jessica Tomaszewski, MD

Pereda MA, Chavez MA, Hooper-Miele CC, et al. Lung ultrasound for the diagnosis of pneumonia in children: a meta-analysis. Pediatrics. 2015;135(4):714-722.

Pneumonia is the leading cause of death among children worldwide. It accounts for 18% of total deaths of children younger than 5 years of age, a rate higher than that of tuberculosis, AIDS, and malaria combined. The diagnosis of pneumonia remains a challenge in areas with limited resources, not only because of the illness’s nonspecific presentation, but also because of the possible lack of access to chest radiography.

Even in areas where radiography is available, medical providers have sought alternative methods for the diagnosis of pneumonia in an effort to limit children’s exposure to ionizing radiation. Moreover, a lack of evidence on radiographs does not exclude a pneumonia diagnosis if strong suspicion exists for it.

With this in mind, Maria A. Pereda, MD, and colleagues conducted a meta-analysis on the accuracy of lung ultrasonography (LUS) in the diagnosis of pneumonia in children. After identifying 1,475 relevant studies and selecting 15 of them for further review, they analyzed 8 studies enrolling a total of 765 children; 6 of the studies were conducted in the general pediatrics population, and the other 2 were in newborns. Various sonographers with various levels of training completed the ultrasonograms in the studies, including physicians and technicians.

The researchers found that the overall pooled sensitivity and specificity of LUS for the diagnosis of pneumonia in children were 96% (95% confidence interval [CI], 94%-97%) and 93% (95% CI, 90%-96%), respectively. Positive and negative likelihood ratios were 15.3 (95% CI, 6.6-35.3) and 0.06 (95% CI, 0.03-0.11), respectively. The area under the receiver operating characteristic curve was 0.98.

In a subgroup analysis, however, the specificity of LUS dropped to 84% when the reference standard was limited to findings based on chest radiography alone. This observation led the authors of the meta-analysis to postulate that chest radiography alone might not be sufficient for the diagnosis of pneumonia in children.

Another interesting observation in this meta-analysis was that the quality of examination depended on a patient’s body habitus and thorax size, meaning that the smaller thoracic view in children lends itself nicely to using LUS as a diagnostic tool. However, this could mean that ultrasonography is less useful for children with a comparatively higher body mass index.

The authors note that the total number of patients covered in the studies in the meta-analysis was smaller than they would have liked, as was the total number of studies examined. Additionally, most of the studies were conducted in high-income countries or areas in which medical resources are more than sufficient. Despite the noted heterogeneity of the studies included, LUS performed well for the diagnosis of pneumonia in children, and it is a technique worth considering as an alternative to chest radiography, especially in resource-challenged areas.

Jessica Tomaszewski, MD, is an assistant clinical professor of pediatrics at the Sidney Kimmel Medical College at Thomas Jefferson University in Philadelphia, Pennsylvania, and a hospitalist pediatrician at Nemours/Alfred I. duPont Hospital for Children in Wilmington, Delaware.

Charles A. Pohl, MD—Series Editor, is a professor of pediatrics, senior associate dean of student affairs and career counseling, and associate provost for student affairs at the Sidney Kimmel Medical College at Thomas Jefferson University in Philadelphia.