A colon polyp is an abnormal growth of tissue arising from the mucous membrane lining the large intestine or rectum. While many are harmless, some types can develop into colorectal cancer over time. The primary goal of a colonoscopy is to provide a complete internal examination of the colon to find and remove these growths before they progress into malignancy. This procedure offers both detection and prevention in a single session.
The Standard Procedure for Polyp Removal
Yes, polyps discovered during a colonoscopy are routinely removed immediately in a procedure known as a polypectomy. This concurrent removal is the central preventive action of the screening process, intercepting the pathway from an abnormal growth to cancer. Polyps that can become malignant, known as adenomas, typically take many years to transform. The rationale for immediate removal is to eliminate tissue that could progress to advanced disease, as the endoscopist cannot definitively determine the tissue type without laboratory analysis. Performing the polypectomy during the colonoscopy avoids the need for a separate, subsequent procedure.
Techniques Used for Polypectomy
The specific method used for polypectomy depends on the polyp’s size, shape, and location.
For very small growths, typically less than three millimeters, the endoscopist often uses cold biopsy forceps. These forceps grasp and tear the polyp away from the colon wall without thermal energy, minimizing the risk of burning the deeper layers of the bowel.
Medium-sized polyps and those on a stalk (pedunculated) are commonly removed using a wire loop called a snare. The snare is looped around the base of the polyp. For larger lesions, an electrical current is applied through the snare in a process called electrocautery. This heat simultaneously cuts the polyp and seals the blood vessels at the resection site to prevent bleeding. A “cold snare” technique uses the mechanical cutting action of the wire loop without electrical current for smaller polyps.
Larger or flatter polyps, especially those exceeding two centimeters, may require Endoscopic Mucosal Resection (EMR). EMR involves injecting a solution, often saline, beneath the polyp to lift it away from the muscular layer of the colon wall. This cushion elevates the lesion, making it safer and easier to remove, often in multiple pieces, using a snare device. This approach ensures a more complete removal without damaging the underlying bowel structure.
When Polyps Require Different Treatment
While most polyps are removed immediately, certain characteristics may necessitate a different treatment plan. Polyps that are very large (greater than two centimeters) or those that are flat and spread out present a higher technical challenge. In these cases, the endoscopist might perform a biopsy to sample the tissue rather than attempting full removal. If the biopsy reveals features suspicious for invasive cancer, or if the polyp is too complex for standard endoscopic removal, the procedure may be stopped. A consultation for surgical resection might then be recommended to ensure complete removal of the tissue and surrounding lymph nodes. To guide future treatment, the endoscopist may perform “tattooing,” injecting a small, inert dye near the site to mark the location for a surgeon or specialized follow-up procedure.
Understanding Polyp Analysis and Follow-Up
Every polyp removed is retrieved and sent to a pathology lab for microscopic examination, known as histology. This analysis determines the cell type, which is the most important factor in assessing future cancer risk. Polyps are broadly classified as non-neoplastic (e.g., hyperplastic polyps, which have a very low risk of becoming cancerous) or neoplastic (which include adenomas and sessile serrated lesions).
The pathology results directly determine the patient’s future screening schedule, referred to as surveillance. If polyps are classified as low-risk, such as only one or two small tubular adenomas, the next colonoscopy is typically recommended in five to ten years. Conversely, high-risk findings shorten the surveillance interval significantly. High-risk findings include the presence of three or more adenomas, any adenoma larger than ten millimeters, or the finding of high-grade dysplasia. Patients in this high-risk category are usually advised to return for a repeat colonoscopy in three years to ensure no new or residual growths develop.