The short answer: A bowel perforation (a hole or tear through the colon wall) is rare. A pooled analysis of more than 10 million colonoscopies by the American Society for Gastrointestinal Endoscopy (ASGE) found 5.8 perforations per 10,000 exams, or about 1 in 1,700. For screening exams the rate is lower, about 3 per 10,000. The main warning signs are belly pain that is severe or keeps getting worse, a swollen or hard belly, and fever.
How common is a perforation from a colonoscopy?
The best estimates come from large population studies, which count every exam in a region or health system. In its 2019 review of colonoscopy adverse events, the ASGE pooled 10,328,360 colonoscopies. The perforation rate was 5.8 per 10,000. Individual studies ranged from 1.6 to 11.9 per 10,000.
Screening exams in healthy adults carry the lowest risk. The evidence review for the US Preventive Services Task Force found 3.1 perforations per 10,000 screening colonoscopies. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) gives the same figure, about 3 in 10,000.
Exams done to look into symptoms tend to carry more risk. A 2016 meta-analysis of 21 population studies found an overall rate of 0.5 per 1,000. Its authors reported that complications were less common in screening and surveillance exams than in diagnostic ones. An older review in the World Journal of Gastroenterology put diagnostic rates between 0.016 and 0.2 percent.
Deaths are rarer still. ASGE counted 3 deaths per 100,000 colonoscopies that were directly tied to a complication or its treatment.
Does removing polyps raise the risk of a tear?
For routine polyp removal, the increase is small. The 2016 meta-analysis found 0.8 perforations per 1,000 exams with polypectomy, compared with 0.5 per 1,000 overall. ASGE noted that an earlier analysis showed a trend of 8 versus 4 per 10,000, but the gap did not reach statistical significance. After adjusting for age and sex, ASGE found that routine polypectomy was not clearly linked to more tears.
ASGE explains that much of the risk comes from the exam itself. Twisting and pressure on the wall as the scope advances can cause a tear. So can air pressure used to open the colon.
The picture changes for large polyps that need advanced removal methods. In ASGE's analysis, endoscopic mucosal resection (EMR), used for large flat polyps, had a perforation rate of 1.1 percent. Endoscopic submucosal dissection (ESD), a deeper technique, had a rate of 7.2 percent. Most of these tears were seen during the procedure and closed on the spot. No deaths from perforation were reported in those studies.
Bleeding is the more common risk after polyp removal. If you see blood in the toilet after a polypectomy, our guide to blood in stool after polyp removal explains what is normal and what is not.
Who is at higher risk of a perforation?
ASGE lists several groups with higher risk:
- Inflammatory bowel disease (IBD). One study found 18.91 perforations per 10,000 exams in people with IBD, against 2.5 per 10,000 without it. That is about 8 times higher.
- Steroid use. Corticosteroids were tied to a 13-fold higher perforation risk.
- Diverticulosis. ASGE lists these colon wall pouches among the higher-risk conditions. Read more in our guide to diverticulosis on a colonoscopy report.
- Other health problems. In Medicare data, stroke, COPD, atrial fibrillation, and heart failure all raised the risk of complications.
- Older age. NIDDK says most bleeding and perforation cases occur in older people or in people who have polyps removed.
Who does the exam also matters. In Canadian data cited by ASGE, doctors in the lowest-volume group (fewer than 141 colonoscopies a year) had about 3 times the odds of a perforation or bleed compared with the highest-volume group. It is reasonable to ask your doctor how many colonoscopies they do.
What are the warning signs of a perforated colon?
Some cramping and gas after a colonoscopy is normal. It comes from the air or carbon dioxide used to open the colon and fades as you pass gas. Our article on pain and bloating after a colonoscopy covers that normal recovery. A perforation feels different because it does not get better.
ASGE describes the early symptoms as persistent belly pain and a swollen belly. NIDDK says to get care right away for:
- Severe pain in the abdomen
- Fever
- Bloody bowel movements that do not get better
- Bleeding from the anus that does not stop
- Dizziness or weakness
Some tears let air escape behind the colon instead of into the belly. ASGE notes this can cause unusual signs, such as chest pain, neck swelling, shortness of breath, or a crackling feeling under the skin.
A key difference: normal gas pain eases as the gas passes. Pain from a perforation persists or gets worse. If you are unsure, call the endoscopy unit. For a broader look at belly pain and when it is urgent, see symptom.md.
When do perforation symptoms usually start?
Most perforations are found during the exam or soon after. In ASGE's review of large polyp removals, most tears were obvious to the doctor at the time.
Delayed perforation can happen, though. ASGE describes a related problem called post-polypectomy electrocoagulation syndrome. Heat from the cutting current burns the wall without making a hole. Patients usually develop fever and pain in one spot 1 to 5 days after the exam. It is usually treated with IV fluids, antibiotics, and bowel rest. A deep burn can turn into a delayed perforation that needs surgery.
So pain that starts or worsens a day or more after polyp removal still needs a call. It should not be dismissed as leftover gas.
What happens if a perforation is found?
The first step is imaging. ASGE notes that a CT scan of the abdomen finds free air better than a plain chest x-ray. The European Society of Gastrointestinal Endoscopy (ESGE) position statement recommends a CT scan for anyone with signs of a perforation after an endoscopy.
Treatment depends on the size of the hole, when it was found, and how sick the patient is:
- Closure with clips during the exam. If the doctor sees the tear, ESGE says it can be closed through the scope, depending on its type and size.
- Close watching in the hospital. The older WJG review describes conservative care with bowel rest and broad-spectrum antibiotics for some patients.
- Surgery. ESGE advises hospital admission and a surgical consult if closure fails, is not possible, or the patient gets worse. MedlinePlus and NIDDK both note that some tears need surgery to repair.
Fast diagnosis improves the odds of a simple fix. That is why the warning signs matter.
The bottom line
A colonoscopy perforation happens in about 3 of every 10,000 screening exams and about 6 of every 10,000 exams overall. Routine polyp removal adds little risk, but advanced removal of large polyps adds much more. IBD, steroid use, diverticulosis, and other illnesses also raise the odds. Severe or worsening belly pain, a swollen or hard belly, and fever are reasons to seek care the same day. Knowing the signs lets you get help early, when treatment is simplest.
Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. If you have severe or worsening pain after a colonoscopy, contact your endoscopy team or go to an emergency room.