Bowel Ultrasound for the Diagnosis of Necrotizing Enterocolitis: A Meta-analysis

Radiographic evaluation for necrotizing enterocolitis (NEC) often yields nonspecific findings. Bowel ultrasound (BUS) provides additional information beyond that of abdominal radiographs and may be helpful in the diagnosis of NEC in neonates. We systematically reviewed and aggregated existing literature to get a better estimate of diagnostic accuracy of BUS in the diagnosis of NEC. A literature search was performed using PubMed, Embase, and Cumulative Index to Nursing and Allied Health Literature to identify studies in which infants with clinically suspected NEC were evaluated using BUS. Studies that used modified Bell staging criteria as the reference standard were included. Study quality was assessed, and pooled sensitivity and specificity of various BUS findings for diagnosing NEC were determined. Six articles with a total of 462 patients met eligibility and inclusion criteria. There was heterogeneity in BUS findings evaluated across studies. Ultrasound detection of classic signs of NEC (portal venous gas, pneumatosis, and free air) had pooled sensitivities ranging from 0.27 to 0.48 and pooled specificities ranging from 0.91 to 0.99. Bowel wall thinning and absent peristalsis had overall low sensitivity (0.22 and 0.30) but high specificity (0.96 and 0.96) for NEC. Assessment of abdominal fluid, which included ascites and focal fluid collection, also had overall low sensitivity and high specificity (simple ascites: 0.45 and 0.92; focal fluid collection: 0.19 and 0.98). In summary, individual BUS findings have low sensitivity and high specificity for diagnosis of NEC. Bowel ultrasound may be a useful adjunct to plain abdominal radiographs in the evaluation of infants with clinical suspicion of NEC.