New meta-analysis quantifies risks of colonoscopy

The risk of perforation during colonoscopy is 5.8 per 10,000, while bleeding occurs in 2.4 per 1,000 colonoscopies, according to a committee report from the American Society for Gastrointestinal Endoscopy.


The risks of colonoscopy were quantified by a recent systematic review and meta-analysis from the American Society for Gastrointestinal Endoscopy's Standards of Practice Committee.

The meta-analysis focused on the three most common and important serious adverse events from colonoscopy (bleeding, perforation, and mortality) and two adverse events (bleeding and perforation) related to endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) for large colon polyps. The review was published online Sept. 25 by Gastrointestinal Endoscopy.

Twenty-one population-level studies of colonoscopy with data on more than 10 million patients (54% women; mean age, 62.3 years) were included. The pooled rate of perforations was 5.8 per 10,000 colonoscopies (95% CI, 5.7 to 6.0). There was significant heterogeneity among studies, with a range in the perforation rate from 1.6 to 11.9 per 10,000. After adjustment, there was no significant association of age, gender, or polypectomy with the risk of perforation.

The risk of bleeding, calculated based on 15 population-level studies with more than 5 million total patients, was 2.4 per 1,000 colonoscopies (95% CI, 2.4 to 2.5). Polypectomy was strongly associated with increased risk of bleeding during colonoscopy: There was a 2.7% increase in risk of bleeding for every 1% increase in rate of polypectomy (P<0.001).

The review included nine studies of colonoscopy-associated mortality, which found that 36 deaths occurred among 1,152,158 colonoscopies, for a pooled death rate of 0.003%. The reviewers noted that the evidence base shows that most deaths within 30 days of colonoscopy are attributable to underlying comorbidities rather than colonoscopy. “Most causes of death directly attributable to colonoscopy were either cardiopulmonary events that occurred during or immediately after the procedure or sequelae of bowel perforation,” they reported.

The meta-analysis of advanced resection techniques found that EMR was associated with a significantly lower rate of perforation than ESD (1.1% [95% CI, 0.9% to 1.4%] vs. 7.2% [95% CI, 6.0% to 8.7%]). However, the rate of postprocedural bleeding was not statistically different between the two techniques. The pooled rate of delayed bleeding was 2.2% (95% CI, 1.5% to 3.0%) after ESD compared to 4.0% (95% CI, 3.5% to 4.5%) after EMR.

The committee's document also provided a narrative review of other adverse events related to colonoscopy: postpolypectomy electrocoagulation syndrome, abdominal discomfort and/or bloating, gas explosion, infection, splenic injury, and sedation-related adverse events. A supplement summarized some rare adverse events, including acute appendicitis and acute diverticulitis.

“Improved knowledge of potential endoscopic [adverse events], their expected frequency, and the risk factors associated with their occurrence may help to minimize the incidence by careful selection of measures to help mitigate the risks associated with colonoscopy and other specific colonoscopic interventions,” the committee said.