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Gastroenterology. 2008 Dec;135(6):1899-1906, 1906.e1. doi: 10.1053/j.gastro.2008.08.058. Epub 2008 Sep 13.

Bleeding and perforation after outpatient colonoscopy and their risk factors in usual clinical practice.

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Department of Medicine, University of Toronto, Toronto, Ontario, Canada.



The most widely quoted complication rates for colonoscopy are from case series performed by expert endoscopists. Our objectives were to evaluate the rates of bleeding, perforation, and death associated with outpatient colonoscopy and their risk factors in a population-based study.


We identified all individuals 50 to 75 years old who underwent an outpatient colonoscopy during April 1, 2002, to March 31, 2003, in British Columbia, Alberta, Ontario, and Nova Scotia, Canada. Using administrative data, we identified all individuals who were admitted to hospital with bleeding or perforation within 30 days following the colonoscopy in each province. We calculated the pooled rates of bleeding and perforation from the 4 provinces. In Ontario, we abstracted the hospital charts of all deaths that occurred within 30 days following the procedure. We used generalized estimating equations models to evaluate factors associated with bleeding and perforation.


We identified 97,091 persons who had an outpatient colonoscopy. The pooled rates of colonoscopy-related bleeding and perforation were 1.64/1000 and 0.85/1000, respectively. The death rate was 0.074/1000 or approximately 1/14,000. Older age, male sex, having a polypectomy, and having the colonoscopy performed by a low-volume endoscopist were associated with increased odds of bleeding or perforation.


Although colonoscopy has established benefits for the detection of colorectal cancer and adenomatous polyps, the procedure is associated with risks of serious complications, including death. Older age, male sex, having a polypectomy, and having the procedure done by a low-volume endoscopist were independently associated with colonoscopy-related bleeding and perforation.

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