American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the screening frequency for flexible sigmoidoscopy?

1. Every year

2. Every 3 years

3. Every 5 years

4. Every 10 years

The correct answer is: Every 5 years

Flexible sigmoidoscopy is recommended as a screening tool for colorectal cancer and is generally performed every 5 years in adults aged 50 to 75. This frequency is based on guidelines that aim to balance the benefits of early detection of colorectal cancer with the potential risks and burdens associated with the procedure, including complications and patient discomfort. Screening every 5 years has been shown to effectively reduce colorectal cancer mortality and detect premalignant lesions, allowing for timely intervention. The rationale for this interval is rooted in research that suggests that cancers and polyps can develop over a period of time, and a 5-year interval is effective for identifying significant changes in the colon that warrant further action or surveillance. Choosing more frequent intervals, such as yearly or every 3 years, may not be necessary for average-risk individuals and could lead to unnecessary procedures or increased anxiety without significant benefits in terms of cancer outcomes. Conversely, extending the interval to every 10 years may miss opportunities for earlier detection of potentially serious conditions, as cancers may develop more rapidly in some individuals. Thus, the 5-year interval strikes a suitable balance for most screening scenarios.