Abdominal free fluid in acute pancreatitis predicts necrotizing pancreatitis and organ failure

BACKGROUND: Abdominal free fluid is frequently encountered on cross-sectional imaging for acute pancreatitis and may be a sign of increased severity and complications. This study examines the ability of free fluid to predict necrotizing pancreatitis and other adverse outcomes. METHODS: We conducted a single-center retrospective study of patients with acute pancreatitis and multiple cross-sectional imaging studies. Patients were divided into those who demonstrated free fluid on initial imaging and those without free fluid. The primary outcome was developing necrotizing pancreatitis. Logistic regression analysis assessed the performance of several predictors. RESULTS: A total of 245 acute pancreatitis patients were included. Pancreatic necrosis occurred more frequently in the free fluid group (31.3 vs. 1.3%, P<0.001). The free fluid group also had higher rates of transient organ failure (17.7 vs. 3.4%, P<0.001), persistent organ failure (17.7 vs. 2.0%, P<0.001), in-hospital mortality (7.3 vs. 1.3%, P=0.016), length of stay (16.2 vs. 5.5 days, P<0.001), and intensive care unit admission (30.2 vs. 4.7%, P<0.001). On multivariate logistic regression, free fluid was the strongest predictor (adjusted odds ratio 17.11, 95% confidence interval 3.68-79.65; P<0.001) for necrotizing pancreatitis, with an excellent performance (area under the curve 0.92). When neither fluid on initial imaging nor persistent systemic inflammatory response syndrome was present, the negative predictive value for developing pancreatic necrosis was 100%. CONCLUSIONS: Free fluid in acute pancreatitis is a strong predictor for necrotizing pancreatitis, organ failure and mortality, and outperformed current predictors. Patients who lacked both free fluid on imaging and persistent systemic inflammatory response syndrome are at low risk for adverse outcomes and may be considered for early discharge.