Lower Endoscopy: Colonoscopy vs. Sigmoidoscopy, Prep, Procedure and Recovery
Updated: 3 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: November 2026 · How we review
Quick Answer: What is a lower endoscopy?
A lower endoscopy is a test that lets a doctor see inside the rectum and colon. A gastroenterologist passes an endoscope, a thin tube with a camera, through the anus to look for bleeding, inflammation or polyps, and can remove polyps or take tissue samples during the same exam. Colonoscopy and sigmoidoscopy are both types of lower endoscopy. [1]
What the research says
One screening colonoscopy lowered colorectal cancer risk. In a randomized trial of 84,585 adults aged 55 to 64, the 10-year risk of colorectal cancer was 0.98% in people invited to screening colonoscopy versus 1.20% with usual care, an 18% relative reduction. (Bretthauer et al., The New England Journal of Medicine, 2022) [2]
Serious complications are rare. A meta-analysis of 21 population-based studies found perforation in 0.5 and bleeding in 2.6 of every 1,000 colonoscopies, with death in 2.9 per 100,000; rates were lower for screening than for diagnostic exams. (Reumkens et al., The American Journal of Gastroenterology, 2016) [3]
Key takeaways
A lower endoscopy uses a camera scope inserted through the anus to examine the rectum and colon. [1]
It can find bleeding, inflammation, polyps and colorectal cancer, and polyps can often be removed during the exam. [1]
Your colon must be empty first, usually with laxatives and/or a clear liquid diet. [1]
An exam of only the rectum takes about 15 minutes; an exam of the whole colon can take about an hour. [1]
Most people eat and return to normal activities the same day. [1]
What is a lower endoscopy used for?
A lower endoscopy is used to find the cause of lower digestive symptoms, to diagnose and monitor conditions of the colon and rectum, and to remove polyps. It is the counterpart to an upper endoscopy, which examines the area from the throat to the top of the small intestine. [1]
Your provider may recommend one if you have: [1]
Diarrhea or constipation
Changes in bowel habits
Cramping or lower belly pain
Rectal bleeding or blood in your stool
It can help diagnose: [1]
Colitis or proctitis
Rectal ulcers and gastrointestinal bleeding
Colorectal polyps and colorectal cancer
It is also used to check whether conditions such as ulcerative colitis are getting worse. [1]
What are the types of lower endoscopy?
The main types of lower endoscopy differ in how much of the large intestine they examine. Ask your provider which one you are having and what to expect. [1]
The scope enters through the anus and moves up the large intestine.
Type | What it examines |
Colonoscopy | The entire colon, rectum and anus |
Sigmoidoscopy | The lower colon, rectum and anus |
Pouchoscopy | A surgically created colon (pouch) |
Sources: [1]
How do you prepare for a lower endoscopy?
To prepare for a lower endoscopy, your colon must be empty so the doctor can see the lining clearly. The exact prep depends on which part of the intestine is being examined, and your provider will give you specific instructions. [1]
For a detailed plan, see our guide to what to eat and drink before a colonoscopy and our bowel prep kit guide.
What happens during a lower endoscopy?
During a lower endoscopy, you lie on an exam table and get medicine to relax you or put you to sleep while the doctor guides the scope through the anus and examines the lining on a video screen. [1]
Most of the work happens the day before, during the bowel prep.
You lie on an exam table.
You receive medicine to relax you or put you to sleep.
The provider inserts the endoscope into the anus.
Video appears on a monitor, and the provider can take photos and save them to your medical record.
Small tools passed through the scope can remove polyps or take tissue samples (biopsies).
The scope is withdrawn, and you rest if you had sedation or anesthesia.
Sources: [1]
Does a lower endoscopy hurt?
A lower endoscopy should not be painful. If you are awake, you may feel pressure as the scope goes in. If you are asleep, you feel nothing, and any discomfort after waking usually lasts only a few hours. [1]
How long does a lower endoscopy take?
How long a lower endoscopy takes depends on the reason for the test and how clean your bowel is. [1]
Exam | Typical time |
Rectum only | About 15 minutes |
Entire colon | About 1 hour |
Sources: [1]
What is recovery like after a lower endoscopy?
Recovery after a lower endoscopy is quick. Some people go home right after the exam; if you were sedated, you recover first and someone else drives you home. You can usually eat and return to normal activities the same day. [1]
Your provider may ask you to limit activity or avoid certain foods for the rest of the day.
What are the benefits and risks of a lower endoscopy?
The main benefit of a lower endoscopy is that it can diagnose and treat many lower digestive conditions in one exam. It is considered safe, but risks include: [1]
Bowel perforation (a tear)
Bleeding
Infection
Complications from anesthesia
These problems are uncommon. In population-based studies, perforation happened in about 0.5 of every 1,000 colonoscopies, rising to 0.8 per 1,000 when polyps were removed. [3]
When should you call your doctor after a lower endoscopy?
Call your healthcare provider if you have any of these after the exam: [1]
Severe or worsening belly pain
More than a tiny amount of rectal bleeding
Fever
Nausea or vomiting
Conclusion
A lower endoscopy is a safe, routine way to look inside your colon and rectum, find the cause of symptoms and remove polyps before they cause harm. Feeling nervous is normal, and following your bowel prep closely gives the clearest result.
If a lower endoscopy has been recommended, ask which type you are having, how to prep and when you will get your results.
Keep learning: Read our guide to colon polyps or our colon cancer guide. For more background, see the NIDDK colonoscopy overview.
FAQ
What is a lower endoscopy?
A lower endoscopy is a test that uses a camera scope inserted through the anus to examine the rectum and colon.
Is a colonoscopy a lower endoscopy?
Yes. Colonoscopy, sigmoidoscopy and pouchoscopy are all types of lower endoscopy.
What is the difference between a colonoscopy and a sigmoidoscopy?
A colonoscopy examines the entire colon, while a sigmoidoscopy examines only the lower colon, rectum and anus.
Why would I need a lower endoscopy?
It checks causes of diarrhea, constipation, belly pain or rectal bleeding, and can find polyps, colitis or colorectal cancer.
How do I prepare for a lower endoscopy?
Your colon must be empty, usually with laxatives and/or a clear liquid diet, and you may need to pause some medicines.
Does a lower endoscopy hurt?
It should not be painful. You may feel pressure if awake, and nothing if you are asleep.
How long does a lower endoscopy take?
An exam of the rectum takes about 15 minutes, and an exam of the whole colon about an hour.
Can I drive after a lower endoscopy?
If you were sedated, you need someone else to drive you home.
What are the risks of a lower endoscopy?
Risks include bowel perforation, bleeding, infection and anesthesia complications, but serious problems are rare.
When should I call a doctor after a lower endoscopy?
Call for severe or worsening belly pain, more than a tiny amount of rectal bleeding, fever, nausea or vomiting.
Related Reading
Colon Polyps: Complete Guide to Symptoms, Causes, and Treatment explains the growths a lower endoscopy finds and removes.
Colon Cancer: Symptoms, Screening, Diagnosis, Treatment and Support covers how colonoscopy fits into screening and diagnosis.
Ulcerative Colitis: Symptoms, Causes, Diagnosis, and Treatment Explained explains a condition that lower endoscopy helps diagnose and monitor.
Learn more in our guide to Flexible Sigmoidoscopy: Prep, Procedure, Results and Risks.
References
Cleveland Clinic. Lower Endoscopy: Procedure To Examine Lower GI Tract. Cleveland Clinic. Last updated January 26, 2026. https://my.clevelandclinic.org/health/procedures/lower-endoscopy
Bretthauer M, Løberg M, Wieszczy P, et al. Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death. N Engl J Med. 2022;387(17):1547-1556. PMID 36214590. https://doi.org/10.1056/NEJMoa2208375
Reumkens A, Rondagh EJA, Bakker CM, et al. Post-Colonoscopy Complications: A Systematic Review, Time Trends, and Meta-Analysis of Population-Based Studies. Am J Gastroenterol. 2016;111(8):1092-1101. PMID 27296945. https://doi.org/10.1038/ajg.2016.234
Medical disclaimer
This article is for general education only and does not replace advice from a qualified healthcare professional. Talk to your doctor about your own diagnosis and treatment, and seek emergency care right away for severe or sudden symptoms.
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