Receiving results from a colonoscopy that mention a polyp can cause concern. Colorectal polyps are common findings during routine screening, representing growths arising from the lining of the colon. Understanding the specific characteristics of the finding, such as its size and shape, is necessary for determining its significance. This information clarifies what a 5 mm sessile polyp represents and what it means for a patient’s health.
What Are Polyps and What Does Sessile Mean
A polyp is an abnormal, localized collection of cells that protrudes from the inner wall of the large intestine. These growths occur when the cells in the mucosal lining divide in an uncontrolled manner. While most polyps are benign when found, they are removed because some types have the potential to change over time.
The term “sessile” describes the shape of the polyp, indicating it has a flat or broad-based attachment to the colon wall. This morphology means the growth lacks a thin stalk, unlike a pedunculated polyp, which resembles a mushroom on a stem. Sessile polyps lie low against the surface of the intestinal lining.
The sessile architecture can sometimes make the polyp slightly more challenging to detect compared to a stalked one. However, modern colonoscopy techniques are highly effective at identifying these subtle, flat lesions. The shape is one of the initial characteristics endoscopists use to classify a polyp during the procedure.
Contextualizing the 5 mm Size
In the context of colorectal screening, a 5 millimeter (mm) polyp is generally considered a small finding. To put this size into perspective, 5 mm is equal to half a centimeter, or about the size of a pencil eraser. This measurement firmly places the polyp in the lowest-risk category used by gastroenterologists.
Clinical guidelines classify polyps based on size to assess risk and determine appropriate follow-up care. Polyps 5 mm or smaller are often termed “diminutive,” while those between 6 and 9 mm are considered “small.” Lesions that measure 10 mm (1 cm) or larger are classified as “large” or “advanced.”
Classifying a 5 mm polyp as diminutive correlates strongly with a low risk of advanced pathology. This size category represents the vast majority of polyps found during screening, with approximately 75% of all polyps detected being 5 mm or less. The small physical size reflects an early stage of development.
Risk and Malignancy Potential
The potential for a polyp to develop into cancer depends more on its cellular type than its size, but size is a reliable indicator of risk progression. Polyps are broadly categorized into non-neoplastic, such as hyperplastic polyps, which are usually harmless, and neoplastic, such as adenomas, which are precancerous. Adenomas follow the adenoma-carcinoma sequence, meaning they can eventually progress to cancer if left untreated over many years.
A 5 mm adenoma, most commonly a tubular adenoma, represents a very early stage in this sequence. Data from large patient registries indicate that the risk of a diminutive adenoma containing high-grade dysplasia—severe cellular changes that precede invasive cancer—is extremely low, often reported as less than one percent. Large-scale studies have found no instances of invasive cancer within polyps measuring 5 mm or less that were examined.
Sessile serrated lesions (SSLs), a specific type of sessile polyp, carry a higher risk profile than common hyperplastic polyps. While SSLs often lack the classic features of adenomas, they are considered precancerous and can progress to cancer more rapidly. Because a 5 mm sessile polyp could potentially be an SSL, its removal and subsequent microscopic analysis are necessary to accurately determine its exact type and risk.
The removal of the polyp eliminates the risk associated with that specific growth. Finding a small polyp means the screening process worked effectively by detecting a potential issue at its earliest stage.
Next Steps and Follow Up Care
The universal practice is to remove any polyp found during a colonoscopy, including the 5 mm sessile lesion, using a biopsy forcep or a small snare. Once removed, the polyp is sent to a pathology lab for a histology report, which is the necessary next step to confirm its precise nature. The pathologist determines whether the polyp is an adenoma, a hyperplastic polyp, or a sessile serrated lesion.
The histology report is the definitive factor that guides the future surveillance timeline, not the initial size alone. For patients who have only one or two small adenomas (less than 10 mm) removed, current medical guidelines often recommend a repeat colonoscopy in 7 to 10 years. This extended interval reflects the low risk associated with these findings and is similar to the screening interval for a person who had a completely normal colonoscopy.
If the pathology report identifies a higher-risk finding, such as multiple small adenomas or a larger sessile serrated lesion, the surveillance interval may be shortened to five years or even three years. Following the specific recommendation from a gastroenterologist ensures appropriate long-term care, based on a full assessment of the polyp’s characteristics and the quality of the initial bowel preparation. The goal of this follow-up is to detect any new polyps before they have a chance to progress.