Sigmoidoscopy: What It Is and What to Expect
Medically reviewed by Sumiran Racherla, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor provides Sigmoidoscopy?
A gastroenterologist, a doctor who treats digestive problems, usually does a sigmoidoscopy. The test is done at an office visit, a hospital, or an outpatient center. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What it is
Flexible sigmoidoscopy is a procedure in which a doctor uses a flexible tube with a camera on one end, called a sigmoidoscope or scope, to look inside your rectum and lower colon. The sigmoid colon is the part of the large intestine just above the rectum. It can show irritated or swollen tissue, ulcers, polyps, and cancer.
Why a doctor might recommend it
A flexible sigmoidoscopy can help a doctor find the cause of symptoms such as the following.
- Bleeding from your anus.
- Changes in your bowel movements, such as diarrhea.
- Pain in your belly.
- Unexplained weight loss.
Rarely, doctors also use it to screen for colon polyps and colorectal cancer. Screening means testing for disease when you have no symptoms.
How to prepare
A health care professional will give you written instructions to follow at home before the procedure. The instructions help you prepare so that little or no stool remains in your large intestine, because stool can prevent your doctor from clearly seeing the lining.
- Talk with your doctor about any health problems you have, and tell your doctor about any medicines, vitamins, and supplements you take.
- You may need to avoid dairy and foods that have a lot of fiber before the test.
- You may also need to follow a clear-liquid diet for a day or more.
- The bowel prep will cause diarrhea, so stay close to a bathroom.
- On the morning of the test, you may be asked to fast, with the exception of certain medicines.
- Be sure to discuss fasting with your provider well in advance.
What happens during it
You lie on your left side with your knees drawn up to your chest. The doctor then inserts the scope through your anus and into your rectum and lower colon. The scope inflates your colon with air for a better view. You may feel pressure or cramping. The procedure usually takes about 10 to 20 minutes. You typically do not need sedatives or anesthesia.
The doctor may remove polyps and send them to a lab for testing. A biopsy takes tissue samples with a tiny tool. You may need to return for a colonoscopy if your doctor finds polyps or other abnormal tissue.
Recovery
After the test, you may feel cramping or bloating in your belly. You can typically return to your normal diet and activities right away if you did not receive a sedative or anesthesia. If the doctor removed polyps or did a biopsy, you may have light bleeding from your anus, and this bleeding is normal. If a biopsy was done, results take a few days or longer to come back.
Seek care right away if you have any of these signs after the test.
- Fever or vomiting.
- Dizziness.
- Weakness.
Call 911 or go to the emergency room if you have trouble breathing, chest pain or discomfort lasting two minutes or more, fainting, coughing up or vomiting blood, severe belly pain or pressure, or bleeding that will not stop.
Risks and side effects
Bleeding and perforation of the colon are the most common complications of flexible sigmoidoscopy, but they are rare. Perforation means tearing a hole in the bowel. Most cases of bleeding occur in patients who have polyps removed. You may have delayed bleeding several days after the procedure. The doctor may need to treat perforation with surgery.
Who performs it
A gastroenterologist usually performs a sigmoidoscopy. Your doctor may combine flexible sigmoidoscopy with other tests.
Common questions
What will I feel during a sigmoidoscopy?
You may feel pressure or cramping during the procedure. You will not feel the removal of polyps. You will not feel a biopsy either.
How is it different from a colonoscopy?
A colonoscopy shows the entire colon. A flexible sigmoidoscopy may take less time than a colonoscopy, and you may not need sedatives or anesthesia.
How does a direct primary care or concierge doctor fit in?
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
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Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
