Is Abdominal Sonography a Useful Adjunct to Abdominal Radiography in Evaluating Neonates with Suspected Necrotizing Enterocolitis

Background Abdominal sonography (AUS) is emerging as a potentially valuable adjunct to conventional abdominal radiography (AXR) in the setting of suspected necrotizing enterocolitis (NEC). We sought to evaluate concordance between AUS and AXR for signs of NEC to better understand the potential advantages and disadvantages of AUS. As a secondary aim, we characterized AUS-specific findings and evaluated the association of imaging results with clinical outcomes. Study Design Hospitalized infants with clinical concern for NEC from 2009-2018 were included in this multi-center retrospective review. All infant patients had at least one paired AXR followed by an AUS within 24 hours. Findings were abstracted from written radiology reports. Cohen’s Kappa, non-parametric Mann-Whitney U-test, and quantile regression were utilized to evaluate chance-corrected levels of agreement for concordance analyses and associations with clinical outcomes. Results In total, 66 patients and 96 paired studies were evaluated. Agreement between the two imaging modalities was 61/96 (63.5%) for pneumatosis (Kappa = 0.29; 95% CI: 0.10-0.48), 79/96 (82.3%) for portal venous gas (Kappa = 0.07, 95% CI: 0.00-0.47) and 91/96 (94.8%) for pneumoperitoneum (Kappa = 0.52, 95% CI: 0.11-0.93). Each finding was present more frequently on AUS than AXR. On AUS, pneumatosis and focal fluid collection were independently associated with a longer antibiotic course (4.1 days longer, p=0.03, and 21.3 days longer, p Conclusions Abdominal sonography holds promise as a useful adjunct to radiography for neonates with possible NEC. It may be more sensitive for the presence or absence of bowel ischemia and can reveal findings not detectable by radiograph that may aid provider decision-making.