P0954 - Abdominal Ultrasound Findings Contribute to a Multivariable Predictive Risk Score for Surgical Necrotizing Enterocolitis

Background/Purpose: Abdominal ultrasound (AUS) is a promising adjunct to abdominal x-ray (AXR) for evaluating suspected necrotizing enterocolitis (NEC). However, predicting which patients will need surgery can be challenging. We sought to develop a multivariable risk score incorporating AUS findings to predict the need for surgical intervention for NEC.

Methods: This was a multicenter retrospective review of 83 patients with suspected NEC from 2009-2018. All patients underwent both AXR and AUS for NEC evaluation. Patients with definitive pneumoperitoneum on AXR were excluded. A subset of patients had surgical NEC and underwent acute laparotomy, primary peritoneal drainage, and/or delayed laparotomy for NEC-related stricture. Demographics, NEC risk factors, physical exam findings, symptoms, and imaging findings at the time of NEC evaluation were reviewed. Multivariate logistic regression determined independent predictors of surgical NEC, which were incorporated into a multivariable risk score. AUC from ROC analysis was calculated. Internal validation was performed using bootstrap resampling.

Results: Of the patients with suspected NEC, 14/83 (16.9%) had surgical disease. Acute intervention was required in 10/83 (12.0%), and delayed surgery only was performed in 4/83 (4.8%). Four independent predictors of surgical NEC were identified: abdominal wall erythema (OR: 8.2, p=0.048), AXR portal venous gas (OR: 29.8, p=0.014), AUS echogenic free fluid (OR: 17.2, p=0.027), and AUS bowel wall thickening (OR: 12.5, p=0.030). A risk score incorporating these four predictors was created with 1 point applied per variable to generate a probability of surgical NEC (Table). The AUC of the risk score was 0.937 (95% CI: 0.879-0.994). Bootstrap model validation results using 1,000 bootstrap resamples indicated good internal validity (Brier score= 0.08, Somers’ D= 0.86).

Conclusion: AUS findings, as an adjunct to physical exam and AXR findings, add predictive value for surgical disease in patients undergoing workup for suspected NEC. This risk score may aid in provider decision making.