Comparison of detection frequencies between ultrasonography and abdominal radiography for abnormal signs in necrotizing enterocolitis: a systematic review and meta-analysis.

OBJECTIVE: To synthesize the existing evidence regarding the differences between abdominal ultrasound (AUS) and conventional radiography in detecting necrotizing enterocolitis (NEC) features in neonates. METHODS: A six-database literature search was conducted to identify relevant English-language studies published prior to April 1, 2026 comparing the detection frequencies of AUS and abdominal x-ray (AXR) for imaging signs of neonatal NEC. RESULTS: Twenty studies were identified that systematically compared the detection frequencies of AUS vs. AXR for detecting specific NEC features (n = 1,793 neonates with confirmed or suspected NEC). AUS detected portal venous gas more frequently than AXR [odds ratio (OR): 2.32; 95% confidence interval (CI) [1.35-3.99]] and exhibits a higher, albeit not significant, detection frequency for pneumatosis intestinalis [OR: 1.21; 95% CI (0.82-1.80)]. AXR detected pneumoperitoneum [OR: 0.62; 95% CI (0.31-1.26)] and intestinal dilatation [OR: 0.51; 95% CI (0.19-1.40)] more frequently than AUS, though neither frequency was statistically significant. CONCLUSIONS: AUS and AXR show different patterns of detection of abnormal signs in NEC, with the former detecting portal gas and pneumatosis intestinalis more frequently than the latter. Combining the two modalities in clinical practice may facilitate earlier recognition and assessment of disease progression in neonatal NEC cases.