A rectal polyp is an abnormal growth that forms on the inner lining of the rectum, the last several inches of the large intestine. These growths are common, especially after age 45, and most are harmless. Some types, however, can slowly develop into cancer over a period of roughly 10 years, which is why finding and removing them early is the whole point of routine screening.
Polyps can be flat against the rectal wall or raised on a stalk, almost like a small mushroom. They range from a few millimeters to over two centimeters. The rectum is actually one of the most common places for polyps to appear, along with the left side of the colon.
Types of Rectal Polyps
Not all polyps carry the same risk. The type is determined by examining the removed tissue under a microscope, and the results directly shape your follow-up plan.
Adenomatous polyps (adenomas) account for about 70 percent of all colorectal polyps, making them the most common type. Only a small percentage of adenomas become cancerous, but nearly all colorectal cancers started as an adenoma. That’s why they get the most attention during screening. Size matters here: larger adenomas and those with certain growth patterns carry higher risk.
Hyperplastic polyps are a type of serrated polyp. They tend to be small, especially in the lower colon and rectum, and are considered extremely low risk for turning cancerous. If your doctor tells you a polyp was hyperplastic, that’s generally reassuring news.
Rarer types exist as well. Peutz-Jeghers polyps appear in a rare genetic syndrome and are linked to higher cancer risk. Juvenile polyps are usually benign on their own, but when many are present (as in juvenile polyposis syndrome), cancer risk goes up. Hamartomatous polyps seen in Cowden syndrome can also raise risk.
How Polyps Become Cancer
The progression from a benign polyp to colorectal cancer is slow. The process is estimated to take about 10 years, which creates a wide window for catching and removing polyps before they become dangerous. This timeline is the reason screening intervals are set the way they are: a colonoscopy every 10 years is frequent enough to interrupt the process for most people at average risk.
Not every polyp will make this journey. Most never become cancerous. But because there’s no reliable way to predict which individual polyp will progress, the standard approach is to remove all polyps found during a screening exam.
Symptoms (or Lack of Them)
Most rectal polyps cause no symptoms at all. You can have polyps and feel completely well, which is exactly why screening matters so much. You can’t rely on your body to alert you.
When symptoms do appear, rectal bleeding is the most common. You might notice blood on toilet paper, on your underwear, or mixed into your stool. Blood can show up as red streaks or make stool look darker than usual. Over time, ongoing low-level bleeding can lead to iron-deficiency anemia, leaving you feeling unusually tired or short of breath without an obvious cause. These symptoms overlap with many other conditions, so they don’t confirm polyps on their own, but they do warrant investigation.
Risk Factors
Age is the single biggest factor. Most people with colorectal polyps are 45 or older, which is why screening recommendations now start at that age. Beyond age, your risk increases if you are overweight, smoke, have a personal history of polyps, or have a family history of advanced polyps or colorectal cancer.
Inflammatory bowel disease, including ulcerative colitis and Crohn’s disease, raises the overall risk of colorectal cancer and typically calls for earlier or more frequent screening. Several inherited genetic syndromes, such as familial adenomatous polyposis and Lynch syndrome, dramatically increase polyp formation and cancer risk, often requiring surveillance starting in the teens or twenties.
How Rectal Polyps Are Found
A colonoscopy is the gold standard for finding rectal polyps because it examines the entire large intestine, including the anus, rectum, and colon. It’s both diagnostic and therapeutic: if a polyp is spotted, it can be removed during the same procedure. If something looks abnormal, a tissue sample can be taken for biopsy. Colonoscopies typically require sedation, so you won’t feel discomfort during the exam.
A sigmoidoscopy is a less invasive alternative that covers only the lower third of the large intestine, focusing on the descending colon, rectum, and anus. Because the rectum is within its reach, a sigmoidoscopy can detect rectal polyps specifically. It usually doesn’t require sedation. The trade-off is that it can’t see the rest of the colon, so a sigmoidoscopy alone isn’t considered a complete cancer screening and is often followed by a full colonoscopy if anything concerning is found.
Other options include stool-based tests (done yearly or every three years depending on the type) and CT colonography, a virtual colonoscopy done every five years. These can flag potential problems, but if they find anything suspicious, you’ll still need a standard colonoscopy for removal and biopsy.
How Polyps Are Removed
Most rectal polyps are removed during the colonoscopy that finds them, a procedure called polypectomy. For smaller polyps, the doctor uses a wire loop (snare) threaded through the scope to clip the polyp off the rectal wall. The experience from your perspective is seamless: you’re sedated, and the removal adds only minutes to the procedure.
Larger or flatter polyps sometimes require endoscopic mucosal resection, a technique where a solution is injected beneath the polyp to lift it away from the surrounding tissue. This creates a cushion that allows the polyp to be cut away without damaging the rectal wall and helps reduce bleeding. Suction further separates the growth from healthy tissue before it’s removed. The treated area is often marked with ink so it can be located easily during future exams.
Recovery from a standard polypectomy is quick. You may feel mild bloating or cramping for a day or so. Your doctor will send the removed tissue to a lab, and the results, usually available within a week or two, determine what type of polyp it was and how closely you need to be monitored going forward.
Follow-Up After Removal
Your next colonoscopy depends on what was found and removed. If your colonoscopy was completely normal with no polyps, the recommendation is to wait 10 years before your next one. If one or two small adenomas (under 10 mm) were removed, the follow-up interval is 7 to 10 years. Three or four small adenomas shorten that to 3 to 5 years, and five to ten small adenomas call for a repeat in 3 years.
For very large polyps (over 20 mm) that had to be removed in pieces, a follow-up colonoscopy is recommended in just 6 months to make sure no tissue was left behind. These intervals are guidelines from a consensus of major gastroenterology organizations, and your doctor may adjust them based on your personal and family history.
Screening Recommendations
The U.S. Preventive Services Task Force recommends that adults begin colorectal cancer screening at age 45 and continue through age 75. For average-risk individuals, a colonoscopy every 10 years is the most common approach, though annual stool-based tests, sigmoidoscopy every 5 years, or CT colonography every 5 years are also accepted options. People with higher risk factors, such as a family history of colorectal cancer or inflammatory bowel disease, typically start earlier and screen more frequently.