Colon Polyps: An Overview

Colon polyps are focal growths of the mucous membrane protruding into the intestinal lumen. They can be benign (hamartomatous, hyperplastic) or neoplastic (adenomas, traditional and sessile serrated lesions). Neoplastic polyps are considered precursors to colorectal cancer via the adenoma → carcinoma and serrated pathways. Early endoscopic diagnosis and timely removal of polyps are the primary means of preventing cancer. [1]

Clinically, small polyps are often asymptomatic and are detected during screening colonoscopy or examination for anemia and occult bleeding. Larger polyps can cause blood in the stool, mucus discharge, changes in bowel habits, and iron deficiency anemia. The presence of polyps does not necessarily indicate cancer, but it does increase the risk, requiring proper removal and monitoring. [2]

In recent years, polyp removal standards have evolved significantly: for small lesions, a "cold" loop without coagulation is preferred, for large flat lesions, endoscopic mucosectomy, and, in select cases, submucosal dissection. This choice of technique reduces the risk of bleeding and perforation and increases the rate of "complete" removal. [3]

Following removal, the key issue is the intervals for follow-up colonoscopy. These are determined by the number, size, and histology of polyps and the quality of the initial colonoscopy; current intervals are regulated by the 2020 US Consensus Group and the 2020–2024 European Society of Gastrointestinal Endoscopy guidelines. [4]

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision (ICD-10), colon polyps are typically coded as K63.5 "Colon polyp." If the polyps are considered benign, D12.6 "Benign neoplasm of colon, unspecified" is used. If an adenomatous nature is detected, the morphology is additionally reflected in the descriptive part of the medical report. [5]

The International Classification of Diseases, Eleventh Revision (ICD-11) uses a "cluster" approach: the basic nosology of "Polyposis or polyp of large intestine" is supplemented by post-coordination features of anatomical, etiological, and morphological features. This approach more accurately reflects the clinical picture and is convenient for statistics and routing. [6]

Table 1. Practical coding

Situation	ICD-10 (example)	ICD-11 (example)	Comment
Colon polyp	K63.5	category of colon polyp with post-coordination	Basic phenotype
Benign neoplasm (polyp)	D12.6	colon polyp + morphology	Please indicate "adenoma", "hyperplastic", etc. in the text
Syndromic polyposis	Condition Codes + History Z-Codes	2E92.40 "Polyposis syndrome" + anatomy	For polyposis as hereditary conditions

Epidemiology

Polyps are a common finding during colonoscopy. In population studies, adenomas are detected in approximately 20-31% of adults during the initial examination, more often in men and with increasing age. The "adenoma detection rate" indicator used by endoscopists serves as a quality indicator. [7]

Polyps are less common in people under 50, but clinically significant lesions are not uncommon; the rising incidence of colorectal cancer at younger ages has become one of the arguments for lowering the screening age to 45 in the United States. This does not mean that cancer is widespread in young people, but it does emphasize the importance of paying attention to symptoms and family history. [8]

The proportion of serrated lesions (sessile serrated and traditional serrated adenomas) among all neoplastic polyps varies across series, but the contribution of the "serrated pathway" to carcinogenesis is recognized as significant, especially in the proximal colon. Errors in recognizing these lesions are associated with their flat shape and pale mucosa. [9]

Regional differences in polyp prevalence and pattern are associated with screening coverage, diet, smoking, and obesity. However, the main conclusion is consistent across all systems: endoscopic detection and removal of polyps reduces future cancer risk. [10]

Table 2. Frequency of detection of adenomas (guidelines based on population series data)

Group	Any adenomas	Comments
Men ≥50 years old	≈ 30%	Higher than women
Women ≥50 years old	≈ 20%	Grows with age
<50 years	Less than 20% (depending on sample)	Significant familial risk and symptoms

Reasons

Neoplastic polyps develop from crypt epithelial cells against a background of accumulating genetic and epigenetic changes. Adenomas are characterized by mutations in genes of the Wnt/β-catenin pathway (e.g., APC), while serrated lesions are characterized by hypermethylation and mutations in BRAF or KRAS, leading to serrated carcinogenesis. These pathways form two main "roads" to colorectal cancer. [11]

Hyperplastic polyps are generally considered benign, but some of them—especially those on the right side and those that are large—are classified as sessile serrated lesions, requiring removal and observation. Correct morphological verification is crucial for management. [12]

A separate group consists of hamartomatous polyps and polyposis syndromes (familial adenomatous polyposis, Peutz-Jeghers syndrome, juvenile polyposis, MUTYH-associated polyposis). They are rare, but pose high risks and require specialized management. [13]

Finally, chronic mucosal inflammation in inflammatory bowel disease, as well as microbial and dietary factors, may contribute to the formation of adenomatous changes, although direct causal links outside of hereditary syndromes are complex and multifactorial. [14]

Risk factors

Uncontrolled factors include age, male gender, and a family history of colorectal cancer or adenomas in first-degree relatives. If these factors are present, screening begins earlier and is performed more frequently. [15]

Modifiable factors include smoking, alcohol consumption, obesity, physical inactivity, a diet high in red and processed meat, and low in fiber. These factors are particularly associated with serrated lesions and high-grade dysplasia adenomas. [16]

Some drug interventions (eg, long-term use of aspirin and nonsteroidal anti-inflammatory drugs) are associated with a reduced risk of adenomas, but the decision to use prophylaxis is individualized, taking into account cardiovascular and gastrointestinal risks. [17]

Inflammatory bowel disease increases the risk of dysplasia and cancer, but the mechanism is different from the sporadic adenoma-carcinoma pathway; separate surveillance protocols are used in these situations. [18]

Table 3. Risk factors for polyps/adenomas (summary of meta-analyses)

Factor	Association with polyps
Smoking	Moderately to strongly increases the risk, especially of serrated lesions
Alcohol	Small to moderate increased risk
Obesity/overweight	Increases the risk of adenomas
Diet: High in red/processed meat, low in fiber	Increases the risk
Physical activity	Reduces the risk

Pathogenesis

The adenomatous pathway is based on inactivation of the APC gene, followed by activation of β-catenin, accumulation of mutations, and transition from low- to high-grade dysplasia and invasive carcinoma. The rate of progression is heterogeneous and depends on molecular changes and the microenvironment. [19]

The serrated pathway involves BRAF or KRAS mutations, epigenetic "locking" of repair genes, and rapid progression to carcinoma in the proximal colon, sometimes bypassing the classic adenomatous stages. These lesions are often flat, mucus-covered, and less visible. [20]

Hyperplastic polyps are mostly biologically inert, but large right-sided lesions are often sessile serrated lesions on re-evaluation, so size and location are critical for management.[21]

Inflammation, microbiota, and dietary factors modify carcinogenesis by influencing epithelial metabolism and the immune response; these areas are actively being researched, but there is already evidence of the benefits of lifestyle modification. [22]

Symptoms

Small polyps are often asymptomatic. Clinical manifestations appear as they increase in size: blood on toilet paper, occult blood loss, mucous discharge, and changes in stool frequency and consistency. Sometimes a polyp is discovered incidentally during screening. [23]

Large polyps can cause anemia, tenesmus, and rare episodes of sub-obstruction. With prolonged presence, ulceration and inflammation around the polyp are possible. The presence of symptoms is not a death sentence, but a reason for an immediate colonoscopy. [24]

Individual polyps in the upper colon (for example, in the cecum) may be asymptomatic and only detectable instrumentally. This explains the importance of a comprehensive colonoscopy, including access to the cecum and adequate bowel preparation. [25]

After removal, there may be a short-term appearance of small bloody discharge; heavy bleeding or severe pain is a reason to immediately consult a doctor. [26]

Classification, forms and stages

Main groups: 1) adenomatous polyps (tubular, tubulovillous, villous) - neoplastic; 2) serrated lesions - sessile serrated, traditional serrated adenomas and hyperplastic polyps; 3) hamartomatous and inflammatory polyps. This approach is adopted in the classification of the World Health Organization. [27]

According to risk, adenomas are classified as "non-advanced" (less than 10 mm, low-grade dysplasia) and "advanced" (10 mm or more, villous component or high-grade dysplasia). This high-risk group also includes traditional serrated adenomas and large sessile serrated lesions. [28]

Syndromic polyposis is classified separately: familial adenomatous polyposis, MUTYH-associated polyposis, Peutz-Jeghers, juvenile polyposis and others - with their own protocols for observation and surgery. [29]

Table 4. Morphological types of polyps

Type	Key Features	Oncological significance
Adenoma (tubular/tubulovillous/villous)	Crypt epithelial dysplasia	Precancerous; risk increases with size/dysplasia
Sessile serrated lesion	Pale, flat, often covered with mucus	An important pathway to cancer in the right sections
Traditional serrated adenoma	Villous architecture + dentation	High risk
Hyperplastic polyp	Small, often distal	Generally low risk
Hamartomatous/inflammatory	Associated with syndromes/inflammation	Tactics are individual

Complications and consequences

The main long-term risk is the progression of some neoplastic polyps to colorectal cancer. The risk is higher with sizes of 10 mm or more, the presence of a villous component and a high degree of dysplasia, as well as with proximal serrated lesions. [30]

Endoscopic removal is safe in most cases, but may be complicated by bleeding and, less commonly, perforation. Modern techniques (cold loop for ≤10 mm, injection and fragmentation for large flat tumors) reduce these risks. [31]

Incomplete polyp removal is a common cause of "false" recurrences and interval cancer. Therefore, protocols emphasize the importance of "complete" en bloc resection of appropriately sized polyps and photo/video documentation of the defect margins. [32]

After polypectomy, proper monitoring intervals are important: too infrequent checkups increase risk, while too frequent ones introduce unnecessary burden and expense without benefit. Formalized scales and recommendations are used as a guide. [33]

When to see a doctor

Seek immediate medical attention if you experience heavy rectal bleeding, melena, severe weakness or dizziness, increasing abdominal pain, or signs of intestinal obstruction. These may be complications of a polyp or polypectomy and require urgent care. [34]

Seek immediate medical attention if you experience recurring bloody discharge, mucus in your stool, changes in bowel habits, unexplained anemia, or a positive occult blood test. These symptoms are indications for a colonoscopy. [35]

If a first-degree relative has had adenomas or colorectal cancer, discuss with your doctor the early start of screening and individualized intervals. Family history changes the approach even in the absence of symptoms. [36]

For people without symptoms and at “average” risk, it is useful to know that in the US, screening is recommended to start at age 45 (there are different tests to choose from), and the optimal method for detecting and removing polyps is colonoscopy. [37]

Diagnostics

The first step is a risk and symptom assessment: family history, age, and signs of blood loss. For those with average population risk, screening options include a stool test for immune hemoglobin once every year, a stool DNA test every three years, a computed tomography colonography every five years, and a colonoscopy every ten years (if normal). A positive noninvasive test is an indication for colonoscopy. [38]

The second step is colonoscopy: the "gold standard" for detecting and simultaneously removing polyps. The quality of the procedure (adequate preparation, reaching the cecum, sufficient endoscope withdrawal time) directly impacts adenoma detection and safety. [39]

The third step is alternative imaging methods when colonoscopy is contraindicated: computed tomography colonography (high sensitivity for lesions ≥10 mm) and capsule colonography (according to European guidelines, an option in selected groups). However, positive findings still require therapeutic colonoscopy. [40]

The fourth step is histology of the removed polyps, indicating the type, size, and degree of dysplasia; this determines the subsequent observation interval. For large flat lesions, the resection technique (mucosectomy, dissection) and hemostasis method are planned in advance. [41]

Table 5. Diagnostic strategies (guidelines)

Method	What does it reveal?	Pros	Restrictions
Colonoscopy	Polyps of any type and size; immediately removed	One-visit treatment	Requires preparation and sedation
Fecal analysis for immune hemoglobin	Blood from foci	Accessible, non-invasive	Can't see a polyp without bleeding
CT colonography	Polyps ≥6-10 mm	Without anesthesia, high specificity	No removal; radiation exposure
Capsule colonography	Polyps ≥6 mm (group selection)	Alternatives for those who refuse endoscopy	Positive findings → colonoscopy

Differential diagnosis

Polyps must be distinguished from inflammatory pseudopolyps in ulcerative colitis and Crohn's disease: the latter arise against a background of chronic inflammation and are not true neoplastic lesions, although the increased cancer risk in these diseases persists. The decision is made based on a combination of clinical, endoscopy, and histological examinations. [42]

Distal hyperplastic polyps should be distinguished from proximal sessile serrated lesions: the latter are flat, pale, and often masked by mucus. Morphology and the endoscopist's experience are critical; if in doubt, re-evaluate the specimens. [43]

Lipomas, submucosal tumors, and inverted diverticula sometimes mimic polyps. Recognizable endoscopic features (mobility, softness, "cushion" sign) and endoscopic ultrasound examination help avoid unnecessary removal. [44]

In case of multiple adenomas, especially at a young age, it is important to exclude hereditary polyposis: familial adenomatous polyposis, MUTYH polyposis, Peutz-Jeghers syndrome, etc. The tactics (including preventive surgery) and examination of relatives depend on this. [45]

Treatment

The mainstay of treatment is endoscopic removal of polyps during diagnostic colonoscopy. For lesions up to 10 mm, "cold" loop resection (without electrocoagulation) is recommended: it ensures a high rate of complete removal and a minimal risk of delayed bleeding. Kitchen tongs for "biting out" small polyps are considered less effective and undesirable. [46]

For polyps measuring 10-19 mm, a "cold" or "warm" loop is selected depending on the morphology and operator experience; for flat polyps, a cold technique with step-by-step removal of fragments is preferred. It is important to avoid "pedestaling" and leaving residual tissue at the edges. [47]

Large flat lesions ≥20 mm are typically removed using endoscopic mucosectomy: injection of a submucosal solution, lifting, and resection into several fragments with careful coagulation of visible vessels. The goal is complete removal with a minimum number of fragments while maintaining safety. [48]

Endoscopic submucosal dissection is indicated selectively—for suspected early cancer requiring en bloc resection or for recurrent lesions after incomplete mucosectomy. This method requires high qualifications and is usually performed in reference centers. [49]

Prevention of bleeding includes evaluation of anticoagulant therapy, the use of clips for large defects, and careful coagulation of vessels. The risk is lower with "cold" resections, but prophylactic clips may be useful for large right-sided defects. [50]

Resection of lesions suspected of invasion should be planned en bloc, based on oncological principles. If submucosal invasion with unfavorable features (poor differentiation, vascular invasion, positive margins) is detected, surgical follow-up treatment is recommended. [51]

After removal, a protocol is compiled with a photo of the defect, precise measurements of the polyp size, and a description of the technique and histology. This data will form the basis for calculating the interval for the next colonoscopy. If a large lesion is fragmented, an early "site-check" colonoscopy at 6 months helps exclude residual tissue. [52]

Post-polypectomy surveillance regimens are standardized. For example, for 1-2 small adenomas (<10 mm), the next colonoscopy is recommended in 7-10 years; for 3-4 adenomas, in 3-5 years; for 5-10 adenomas or any polyp ≥10 mm, villous component, or high-grade dysplasia, in 3 years; after sectional resection of a large lesion, an early check-up is at 6 months. (Intervals may vary slightly between regional guidelines.) [53]

Serrated lesions are followed according to similar principles: small sessile serrated lesions without dysplasia - interval 5-10 years; large ≥10 mm or with dysplasia - 3 years; traditional serrated adenoma - 3 years. Confidence in complete removal and the quality of the initial colonoscopy are important. [54]

The role of medicinal "chemoprophylaxis" (aspirin, nonsteroidal anti-inflammatory drugs) remains supportive and does not replace endoscopy. The decision to use these agents to reduce the risk of adenomas is made individually, taking into account comorbidities; systematic reviews confirm a moderate effect on the risk of adenomas, but the balance of benefits and harms should be assessed by a physician. [55]

Table 6. Removal technique - "what to choose"

Polyp	Recommended method	Why is this so?
≤10 mm, any section	Cold loop	The more complete the resection, the lower the risk of bleeding.
10-19 mm flat	Cold loop (in parts)	Safe, effective
≥20 mm flat	Endoscopic mucosectomy	Controlled fragmentation with hemostasis
Suspicion of invasion	Dissection in the submucosal layer	"En bloc" for precise oncological assessment

Table 7. Observation intervals after polypectomy (guidelines for high-quality colonoscopy)

Findings	Next colonoscopy
1-2 adenomas <10 mm	7-10 years
3-4 adenomas <10 mm	3-5 years
≥5 adenomas, any adenoma ≥10 mm, villous component or high grade dysplasia	3 years
Resection of a large lesion in parts	6 months (site-check)
Small, sessile, serrated teeth without dysplasia	5-10 years
Sessile serrated adenomas ≥10 mm or with dysplasia; traditional serrated adenoma	3 years

Prevention

The best way to prevent cancer is to detect and remove polyps as part of screening. In the United States and some countries, screening is recommended to begin at age 45 for those with average risk; older age groups are monitored based on individual indications. The choice of test should be discussed with a doctor. [56]

Lifestyle modifications complement, but do not replace, screening: quitting smoking, drinking alcohol in moderation, maintaining a healthy weight, eating enough fiber, limiting red and processed meat, and engaging in regular physical activity. These measures reduce the risk of adenomas and cancer. [57]

When taking anticoagulants and antiplatelet agents, the polypectomy plan and preparation are discussed in advance to reduce the risk of bleeding and avoid compromising vital thromboprophylaxis. This is the standard for safe endoscopy. [58]

Individuals with a family history of early colorectal cancer or multiple adenomas and patients with polyposis syndromes undergo in-depth monitoring using separate protocols, including genetic counseling. [59]

Forecast

After complete removal of polyps and adherence to surveillance intervals, the long-term prognosis is favorable: the risk of colorectal cancer is significantly reduced compared to no screening. The key to success is the quality of the initial colonoscopy and the completeness of the resection. [60]

Recurrences are more often associated with residual tissue after fragmentary resection of large lesions; hence the recommendation of early "site check" and, if possible, "en bloc" resection when invasion is suspected. By adhering to these principles, the risk of interval cancer is minimized. [61]

Patients with proximal serrated lesions, large adenomas and multiple lesions require more frequent follow-up; these groups constitute the main contributor to the residual risk and require discipline. [62]

Overall, the introduction of modern polypectomy techniques and surveillance algorithms in 2020–2024 improved the safety of interventions and reduced the number of missed lesions, particularly in the right colon. [63]

FAQ

1) Should all polyps be removed?
Neoplastic polyps (adenomas, sessile, and traditional serrated lesions) are always removed. Small distal hyperplastic polyps can sometimes be simply observed, but the decision is made by the endoscopist after a thorough examination. [64]

2) Is polyp removal painful?
Polypectomy is performed during a colonoscopy under sedation; the resection itself is painless. Short-term discomfort and rare complications (bleeding, perforation) are possible, but are discussed in detail in advance. [65]

3) What's the best test for a "first step"?
The most sensitive and "one-visit-and-cure" is a colonoscopy. But if you prefer a noninvasive start, consider an annual stool test for immune hemoglobin or a CT colonography every 5 years; even with positive findings, a colonoscopy is still necessary. [66]

4) When should I return for my next colonoscopy after polyp removal?
This depends on the number, size, and morphology of the removed lesions and the quality of the initial examination. For example, for 1-2 small adenomas, the interval should be 7-10 years; for 5 or more adenomas or any adenoma ≥10 mm, the interval should be 3 years; and after fragmentary resection of a large lesion, the interval should be 6 months. Check with your doctor about the interval. [67]