An intestinal polyp is any mass of tissue that arises from the bowel wall and protrudes into the lumen. Most are asymptomatic except for minor bleeding, which is usually occult. The main concern is malignant transformation; most colon cancers arise in a previously benign adenomatous polyp. Diagnosis is by endoscopy. Treatment is endoscopic removal.
Polyps may be sessile or pedunculated and vary considerably in size. Estimates of adenoma prevalence are based on studies of colonoscopy, which generally report adenomas in 20 to 53% of individuals 50 years or older, including up to 9.7% with advanced adenomas (1–3). Polyps, often multiple, occur most commonly in the rectum and sigmoid and decrease in frequency toward the cecum. Multiple polyps may represent familial adenomatous polyposis or its attenuated variant. The prevalence of cancer in colorectal polyps ranges from 0.2% to 5% (4).
Adenomatous (neoplastic) polyps are of greatest concern. Adenomatous polyps ≥ 10 mm in size or with villous or high-grade dysplasia (termed “advanced adenomas”) pose a higher risk of progression to cancer. Studies estimate approximately 1 to 5% annual progression rates of advanced adenomas to colorectal cancers, with rates in the lower range for women overall; rates are typically on the higher end in older age groups (5).
Nonadenomatous (nonneoplastic) polyps include hyperplastic polyps, hamartomas (see Peutz-Jeghers Syndrome), juvenile polyps, pseudopolyps, lipomas, leiomyomas, and other rarer tumors. Juvenile polyps occur in children, typically outgrow their blood supply, and autoamputate some time during or after puberty. Treatment is required only for uncontrollable bleeding or intussusception. Inflammatory polyps and pseudopolyps occur in chronic ulcerative colitis and in Crohn disease of the colon. Multiple juvenile polyps (but not sporadic ones) convey an increased cancer risk. The specific number of polyps resulting in increased risk is not known.
This image shows a sessile, multilobulated polyp, which, on biopsy, turned out to be a benign tubular adenoma.
Image provided by David M. Martin, MD.
This image shows a pedunculated polyp, which, on biopsy, turned out to be a benign tubular adenoma.
Image provided by David M. Martin, MD.
This image shows a sessile polyp, which, on biopsy, turned out to be a tubulovillous adenoma.
Image provided by David M. Martin, MD.
This image shows a sessile, multilobulated polyp, which, on biopsy, turned out to be a benign tubular adenoma.
Image provided by David M. Martin, MD.
This image shows a pedunculated polyp, which, on biopsy, turned out to be a benign tubular adenoma.
Image provided by David M. Martin, MD.
This image shows a sessile polyp, which, on biopsy, turned out to be a tubulovillous adenoma.
Image provided by David M. Martin, MD.
References
1. American Cancer Society. Colorectal Cancer Facts & Figures, 2023–2025. Accessed February 4, 2025.
2. Oines M, Helsingen LM, Bretthauer M, Emilsson L. Epidemiology and risk favors of colorectal polyps. Best Pract Res Clin Gastroenterology. 31(4):419-424.
3. Levine JS, Ahnen DJ. Clinical practice. Adenomatous polyps of the colon. N Engl J Med.2006;355(24):2551-2557. doi:10.1056/NEJMcp063038
4. Shaukat A, Kaltenbach T, Dominitz JA, et al. Endoscopic Recognition and Management Strategies for Malignant Colorectal Polyps: Recommendations of the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2020;159(5):1916-1934.e2. doi:10.1053/j.gastro.2020.08.050
5. Sullivan BA, Noujaim M, Roper J. Cause, Epidemiology, and Histology of Polyps and Pathways to Colorectal Cancer. Gastrointest Endosc Clin N Am. 2022;32(2):177-194. doi:10.1016/j.giec.2021.12.001
Symptoms and Signs of Colorectal Polyps
Most polyps are asymptomatic. Rectal bleeding, usually occult and rarely massive, is the most frequent complaint.
Cramps, abdominal pain, or obstruction may occur with a large lesion.
Rectal polyps may be palpable by digital examination. Occasionally, a polyp on a long pedicle may prolapse through the anus.
Large villous adenomas may rarely cause watery diarrhea that may result in hypokalemia.
Diagnosis of Colorectal Polyps
Colonoscopy
Diagnosis of colonic polyps is usually made by colonoscopy. Barium enema, particularly double-contrast examination, is effective, but colonoscopy is preferred because polyps also may be removed during that procedure. Because rectal polyps are often multiple and may coexist with cancer, complete colonoscopy to the cecum is mandatory even if a distal lesion is found by flexible sigmoidoscopy.
During colonoscopy, any polyps seen are removed and evaluated for possible cancer.
Treatment of Colorectal Polyps
Complete removal during colonoscopy
Sometimes follow with surgical resection
Follow-up surveillance colonoscopy
Polyps should be removed completely with a snare or biopsy forceps during total colonoscopy. If colonoscopic removal is unsuccessful, laparotomy should be done.
Subsequent treatment depends on the histology of the polyp. If dysplastic epithelium does not invade the muscularis mucosa, the line of resection in the polyp’s stalk is clear, and the lesion is well differentiated, endoscopic excision and close endoscopic follow-up should suffice. Patients with deeper invasion, an unclear resection line, or a poorly differentiated lesion should have segmental resection of the colon. Because invasion through the muscularis mucosa provides access to lymphatics and increases the potential for lymph node metastasis, such patients should have further evaluation (as in colon cancer).
The scheduling of follow-up examinations after polypectomy is controversial and varies by the number, size, and type of polyps removed (1). For example, guidelines recommend a repeat total colonoscopy (or barium enema if total colonoscopy is impossible) 3 years after removal of a tubular adenoma ≥ 10 mm or a villous adenoma of any size.
Treatment reference
1. Gupta S, Lieberman D, Anderson JC, et al. Recommendations for Follow-Up After Colonoscopy and Polypectomy: A Consensus Update by the US Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 115(3):415-434, 2020. doi: 10.14309/ajg.0000000000000544
Prevention of Colorectal Polyps
Aspirin and COX-2 inhibitors may reduce the risk of colon cancer (Aspirin and COX-2 inhibitors may reduce the risk of colon cancer (1). The potential benefits of long-term therapy with these agents must be weighed against the potential adverse effects (eg, bleeding, renal dysfunction).
Prevention reference
1. Liang PS, Shaukat A, Crockett SD. AGA Clinical Practice Update on Chemoprevention for Colorectal Neoplasia: Expert Review. Clin Gastroenterol Hepatol. 2021 Jul;19(7):1327-1336. doi: 10.1016/j.cgh.2021.02.014
Key Points
Colonic polyps are common; the prevalence of adenomatous polyps is approximately 20 to 53% of individuals 50 years or older.
The main concern is malignant transformation, which occurs at different rates depending on the size and type of polyp.
The main symptom is bleeding, usually occult and rarely massive.
Colonoscopy is the recommended diagnostic and therapeutic procedure.
