Outpatient ERCP is increasingly being adopted and already recommended in selected patients to optimise resource allocation without compromising safety, yet unplanned hospital readmission remains a key concern, particularly when driven by post-procedure complications. This study evaluated 30-day readmission after outpatient ERCP in a medium-volume centre performing 200–300 ERCPs/year, aiming to characterise real-world safety outcomes and identify independent predictors of early unplanned admission.

A retrospective analysis was conducted of all ERCPs performed between January 2021 and December 2024 (n=840). Of these, 304 ERCPs were undertaken in the outpatient setting and were included in the primary analysis. The outcome was 30-day unplanned hospital readmission. Variables were grouped into patient, indication, findings, and procedure-related categories. Logistic regression was used for univariate analysis, and variables with p<0.15 were included in a multivariate model (stepwise). A p-value <0.05 was considered significant. Statistical analysis was done with SPSS v29.0.

Among 304 outpatient ERCPs, the 30-day readmission rate was 9.5% (29/304). Readmissions were mainly complication-driven, most frequently due to post-ERCP pancreatitis in 1.6% (5/304), cholangitis in 3.3% (10/304), cholecystitis in 2.0% (6/304), perforation in 0.3% (1/304), and other complications in 2.3% (7/304). Overall cannulation success was high, at 289/298 (97.0%), including 154/161 (95.7%) in naïve papillae. In univariate analysis, several variables were significantly associated with 30-day readmission. Malignant obstruction as the index indication increased the odds of readmission (OR 3.23, CI 1.15–9.11), as did malignant obstruction confirmed during ERCP (OR 2.76, CI 1.25–6.11). Sphincterotomy was also associated with increased risk (OR 2.29, CI 1.05–4.99). Conversely, a previous ERCP status (with sphincterotomy) reduced the risk of hospital admission (OR 0.35, CI 0.14–0.85), as did suspected choledocholithiasis as the indication (OR 0.45, CI 0.21–0.97). Male sex also showed a near significant protective trend (OR 0.48, CI 0.20–1.12, p=0.09). The multivariable model retained three variables. Previous sphincterotomy remained independently protective for readmission (OR 0.30, CI 0.11–0.83), suggesting that patients with an already-accessed papilla may have lower procedural complexity and fewer early adverse events. Male sex continued to show a near-significant protective effect (OR 0.43, CI 0.18–1.03, p=0.06). Malignant obstruction as indication emerged as the strongest independent predictor of early readmission (OR 5.46, CI 2.07–14.42), consistent with more severe underlying disease and greater procedural complexity.

In our medium-volume centre, outpatient ERCP was safe, with a low rate of early unplanned hospitalisation and high cannulation success. Malignant obstruction as the indication remained the primary driver of early readmission, highlighting the need for enhanced peri-procedural planning and post-procedural vigilance in this subgroup. Protective factors, including previous sphincterotomy and male sex, may help refine risk stratification. These findings contribute real-world data supporting the safety of ambulatory ERCP and offer practical insight into patient selection and identifying higher-risk patients who may benefit from tailored monitoring strategies and more selective outpatient scheduling.