A colonoscopy is a standard medical procedure designed to protect against colorectal cancer. It acts as a preventative tool by allowing a physician to examine the lining of the large intestine and remove abnormal growths, known as polyps. The primary goal of this screening is to interrupt the progression of these growths, which effectively reduces the risk of developing the disease. Understanding the procedure’s findings, particularly the number of polyps removed, helps determine a patient’s future surveillance needs.
Defining Colonic Polyps
Polyps are abnormal collections of cells that grow on the inner wall of the colon or rectum. They are common, and most are benign, meaning they are non-cancerous. Polyps are removed during a colonoscopy, a process called polypectomy, because some types have the potential to eventually transform into cancer.
Colonic polyps are broadly categorized into two main groups based on their potential for malignant change. Hyperplastic polyps are typically considered very low risk and rarely become cancerous. The more significant category includes adenomas and sessile serrated polyps, which are considered pre-cancerous lesions. Adenomas are the most common type found during screening and are responsible for the majority of colorectal cancers if left untreated.
The Statistical Norm: Average Polyp Count
It is common for a person undergoing a screening colonoscopy to have zero polyps found, as studies show that over half of average-risk patients have no lesions detected. However, finding one or two polyps is also frequent, especially in older adults. In large-scale studies, the mean number of detected polyps per procedure is reported to be around 1.5.
The number of polyps removed is often less important than the type, size, and specific features of the most advanced polyp found. For example, multiple small, benign hyperplastic polyps are considered a low-risk finding. Conversely, finding even one polyp that is large (10 millimeters or greater), has villous features, or shows high-grade dysplasia is associated with a significantly higher future risk.
The prevalence of polyps increases with age; approximately 50% of people aged 60 or older have at least one adenomatous polyp. Other factors that influence the likelihood of finding polyps include gender (men typically have a higher prevalence than women) and a personal or family history of colorectal cancer. The results for any individual patient will vary widely based on their unique risk profile and biological factors.
Implications of Polyp Findings
The surveillance plan following a colonoscopy is determined by the pathologist’s detailed report on the removed polyps. This report specifies the number, size, and histological type of the most concerning lesions, which dictates the necessary follow-up interval. Patients who have no polyps, or only small, distal hyperplastic polyps, are considered low-risk and advised to return for a repeat screening in the standard 10 years.
A shorter surveillance interval is recommended when findings increase the patient’s risk of developing future polyps or cancer. For instance, finding one or two small adenomas often leads to a recommendation for the next colonoscopy in five to ten years. An accelerated surveillance schedule is required for findings that carry high-risk features.
High-risk findings generally include:
- Three to ten small adenomas.
- Any adenoma that is 10 millimeters or larger in size.
- Polyps with specific high-risk characteristics, such as villous features or high-grade dysplasia, warranting a repeat colonoscopy in approximately three years.
- More than ten adenomas found during the procedure, which may require an even sooner follow-up.