- Background and Aims Unplanned hospital visits within 7 days of colonoscopy were recently proposed as a quality measure. It is unknown whether patient, procedure, or endoscopist characteristics predict post-colonoscopy emergency department (ED) visits. Our aim was to determine the incidence and relatedness of ED visits within 7 days of colonoscopy and to identify predictors of post-colonoscopy ED use. Methods In this retrospective, single-center, cohort study, we evaluated outpatient colonoscopies performed at a tertiary academic medical center or affiliated facility between January 2008 and September 2013. We determined the incidence of ED visits within 7 days of colonoscopy and the relatedness of the ED visit to the procedure. We assessed for independent factors associated with ED use within 7 days using logistic regression analysis. Results We reviewed 50,319 colonoscopies performed on 44,082 individuals (47% male, median age 59 years) by 40 endoscopists. There were 382 (0.76%) ED visits after colonoscopy, of which 68% were related to the procedure. On multivariate analysis, recent ED visit (odds ratio [OR], 16.60; 95% confidence interval [CI], 12.83-21.48; P < .001), EMR (OR, 4.69; 95% CI, 2.82-7.79; P < .001), number of medication classes (OR, 1.18; 95% CI, 1.11-1.26; P < .001), endoscopist adenoma detection rate (ADR) (OR, 1.14; 95% CI, 1.01-1.29; P = .029), and white race (OR, 0.77; 95% CI, 0.62-0.97; P = .028) were identified as independent variables associated with ED visits after colonoscopy. Conclusions Increased patient complexity, higher endoscopist ADR, and EMR were associated with increased ED use after colonoscopy. Patients at high risk for an unplanned hospital visit within 7 days should be targeted for quality improvement efforts to reduce adverse events and cost.