What is a colonoscopy?

From the Guidelines

A colonoscopy is a medical procedure that examines the large intestine (colon) and rectum using a flexible tube with a camera called a colonoscope, and it is the primary method employed for colorectal cancer screening in average- and high-risk populations. It's recommended as a screening test for colorectal cancer starting at age 45 for average-risk individuals, then typically every 10 years if results are normal, as stated in the NCCN guidelines 1. Before the procedure, patients must complete a bowel preparation regimen, usually involving a clear liquid diet for 24-48 hours and drinking a bowel-cleansing solution such as GoLYTELY, MoviPrep, or SUPREP the day before. These solutions flush out the colon to ensure clear visibility. Patients should arrange transportation home as sedation is typically used during the procedure. During a colonoscopy, the doctor can remove polyps (precancerous growths) and take tissue samples for biopsy. The procedure itself takes about 30-60 minutes, though patients should plan for 2-3 hours total at the medical facility.

Key Points to Consider

• Colonoscopy has limitations and may not detect all cancers and polyps, as noted in the NCCN guidelines 1.
• Accumulating data suggest that substantial variability exists in the quality and, by extension, the clinical effectiveness of colonoscopy, highlighting the need for a programmatic approach to address quality issues 1.
• The NCCN guidelines emphasize the importance of individual risk factors and physician judgment in determining the interval between colonoscopies, as well as the need for standardized colonoscopy reports and quality indicators such as cecal intubation rates and adenoma detection rates 1.
• Other screening modalities, such as stool-based testing and flexible sigmoidoscopy, may be used in combination or as alternatives to colonoscopy, but the choice of screening test should be based on patient preferences and risk factors, as recommended by the USPSTF and other organizations 1.
• Emerging technologies, such as stool DNA testing, may also be used as screening tools, but the evidence is still limited and the optimal screening interval is uncertain 1.

Quality of Life and Morbidity Considerations

• Colonoscopies are crucial for early detection of colorectal cancer, which is highly treatable when caught early, and can improve quality of life and reduce morbidity and mortality 1.
• The procedure is generally safe, though rare complications can include bleeding or perforation of the colon wall, and patients should be informed of these risks and benefits before undergoing the procedure 1.

From the Research

Definition of Colonoscopy

• Colonoscopy is the gold standard for visualization and diagnosis of conditions involving the colon and terminal ileum 2
• It also facilitates screening and prevention of colorectal cancer, which is the second leading cause of cancer death in the USA 2

Purpose of Colonoscopy

• The most important goal of optimal bowel preparation is to reduce the incidence of colorectal cancer 3
• Colonoscopy is an important diagnostic and screening tool for colorectal cancer detection and prevention 4

Importance of Bowel Preparation

• Optimal bowel preparation is essential for a more accurate, comfortable, and safe colonoscopy 3
• Adequate bowel preparation is critical for successful colonoscopy 4
• Inadequate bowel preparation can lead to missed polyps or inadequate examination, which can result in postcolonoscopy colorectal cancers 3

Types of Bowel Preparation

• Laxatives for oral colonoscopy bowel preparation can be classified into polyethylene glycol (PEG)-electrolyte lavage solution, osmotic laxatives, stimulant laxatives, and divided into high-volume solution (≥3 L) and low-volume solution (<3 L) 3
• The updated 2019 European Society of Gastrointestinal Endoscopy (ESGE) guideline suggests the use of high volume or low volume PEG-based regimens as well as that of non-PEG based agents that have been clinically validated for most outpatient scenarios 3

Patient Factors Affecting Colonoscopy

• Risk factors for inadequate bowel preparations include poor adherence to split preparation instructions or volume of solution ingested, and certain patient-related medications and comorbidities, such as diabetes, elevated body mass index, and antidepressant or narcotic use 4
• Patient-related factors, such as decline of colonoscopy, can be a barrier to follow-up colonoscopy 5