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Colonoscopy Quality: What Is It And Why It Matters

Colonoscopy is an essential component of colorectal cancer (CRC) screening. Colonoscopy is generally a very safe procedure but growing demands for screening-related colonoscopy challenges us to provide high-quality colonoscopy at minimal risk to patients.

CRC screening has clear benefits in terms of reducing the mortality and incidence of CRC. However, every patient undergoing a screening colonoscopy is at risk of potential complications. These could be direct procedural-related complications such as perforation or bleeding. Or they could be bowel preparation- related complications, or any number of secondary complications such as cardiac ischemia, or the consequences of missed lesions. In contrast symptomatic patients undergoing the same investigation have a more balanced benefit-to-risk ratio.

Quality of Colonoscopy

Broadly speaking there are two key components of colonoscopy: 1) examining the colon to the cecum completely, safely, and comfortably; and 2) the detection of adenomas and more advanced lesions and their subsequent complete removal.

There are several validated indicators of colonoscopy quality. Cecal intubation rate (CIR) is the percentage of cases the colonoscope is advanced beyond the ileocecal valve into the cecal pole and/or the terminal ileum. The target CIR is 95%. Having a high CIR ensures adequate visualization and reduces the need for repeat procedures and additional investigations. High CIR with maintained high patient comfort rates, and low perforations rates, are auditable measures of the skill of endoscopy technique.

High levels of polyp, and more importantly adenoma detection rates (ADR), are defined as the proportion of patients that have at least one adenoma identified and removed during colonoscopy. For screening colonoscopies, the ADR should be at least 20%. High ADR’s correlate with low levels of missed and interval cancers.

Ontario has adopted a minimal number of colonoscopies per year (200) as a surrogate of the other measured outcomes.

Complications of colonoscopy

Complications of colonoscopy include bleeding, perforation, sedation-related complications, and bowel prep-induced complications (dehydration, metabolic disturbances, seizures and falls). The generally accepted rate of perforation is less than 1 in 2000 screening colonoscopies (<0.05%). Some consider this rate to be high, and aim for 1 perforation per 5000 colonoscopies. Bleeding is more common, occurring in 1 in 500 colonoscopies with polypectomy. Sedation-related complications are more commonly seen when reversal agents are given. US studies indicate that the use of propofol for colonoscopy is associated with a risk of aspiration pneumonia of as high as 1 in 500.

Quality of the patient experience

It is important to consider the patient journey through endoscopy services, including the pre-procedural interventions, the level of empathy and respect shown by all staff, and the post-procedural aspects. The care of patients following an endoscopy is critical for a good patient experience and for safety and quality reasons. This includes the immediate post- procedure recovery and discharge, with post-procedure patient education. A clear plan should exist for the follow-up of pathology, and that evidence-based guidelines are followed for recall colonoscopies that are based on the polyp size and pathology. This information also needs to be clearly communicated to the primary care physician.


Quality is a critical component of the CRC screening pathway. While there is often a concentration on scoping procedural quality, the pre and post- procedural components also need to be of high quality. Lastly, effective communication of post-procedural care and follow-up to primary care physicians is critical for the appropriate re-entry of patients into the screening or surveillance cycles.

Article written by: Dr. Alaa Rostom, Regional Colorectal Screening GI and Endoscopy Lead

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