INTRODUCTION: Post-ERCP pancreatitis (PEP) occurs in up to 15% of high risk patients. Symptoms after ERCP are common and usually determine admission. However, discharge of outpatients at risk for PEP is frequent after ERCP. In retrospective studies, discharged PEP patients are at increased risk for severity, possibly due to delays in IV fluid therapy. The aim of this study is to evaluate clinical predictors and outcomes in patients discharged and later admitted with delayed presentation of PEP. METHODS: We identified consecutive outpatients with PEP enrolled in a prospective study designed to evaluate the optimal rectal Indomethacin dose for prevention of PEP in high-risk patients. All patients received Indomethacin and were observed for at least 4 hours post-ERCP per protocol. All clinical data except IV fluids, recovery medications, and pain scores were collected prospectively. Diagnosis and severity of PEP was defined by Cotton criteria. RESULTS: 107/720 (14.9%) developed PEP. 135/720 (18.8%) were directly admitted after ERCP. While the direct admission rate in patients that developed PEP was higher (P < 0.001), 58/107 (54.2%) were discharged and had a delayed presentation of PEP. Median time to presentation was 24 hours (IQR 15–31.75 h). Discharged patients were older (age 47.7 vs 41.1, P = 0.026), more often had a morning procedure (59.2% vs 39.7%, P = 0.044), less often had pancreatic stent placement (82.8% vs 95.9%, P = 0.032), spent less time in recovery (261 vs 312 minutes, P = 0.004), required less IV opioids (6.4 vs 17.3 MME, P < 0.001) and had lower pain scores (2.8 vs 6.5, P < 0.001) (Table 1). On multivariable analysis, an afternoon procedure (OR 4.00, P = 0.016) and pain score >3 (OR 1.37, P = 0.001) were associated with admission. While discharged patients were more likely to present with SIRS on admission (43.1% vs 10.2%, P < 0.001), a delayed presentation was not associated with severe PEP (Table 2). CONCLUSION: Delayed presentation of PEP after discharge of high-risk patients is frequent, but not associated with adverse outcomes or severe PEP. Systematic deployment of PEP prophylaxis with rectal Indomethacin, pancreatic stents, and IV fluids may attenuate the impact of delayed presentation on outcomes. Afternoon procedure time and increased pain appear to influence decisions to admit. However, given the frequency of delayed presentation of PEP, accurate and early diagnostic tests for PEP may be of clinical value.