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Results
You will usually hear what the doctor saw on the same day. Biopsy results generally take several days to a couple of weeks, and your doctor will explain what they mean and whether you need more tests, such as a full colonoscopy.
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
What is it?
In a flexible sigmoidoscopy, a doctor passes a thin, flexible tube with a light and camera (a sigmoidoscope) through the anus to look at the inside of the rectum and the sigmoid colon, the lower part of the large bowel. It looks at about the last third or less of the colon, unlike a full colonoscopy, which examines the whole colon. Small tissue samples (biopsies) can be taken during the test.
Why is it done?
It helps find the cause of rectal bleeding, diarrhoea, changes in bowel habit or pain in the lower bowel, check how active ulcerative colitis or Crohn’s disease is, look for inflammation after treatment, and detect polyps or growths in the lower colon. If something important is found, you may need a full colonoscopy.
Who needs it?
- People with rectal bleeding or blood in the stool that needs a cause found
- People with ongoing diarrhoea or a change in bowel habit
- People with ulcerative colitis or Crohn’s disease, to judge activity or response, or when severe colitis needs a quick look
- Selected people when a limited examination is suitable, or when a full colonoscopy is not possible
Before the procedure
- Your team will give written instructions. Most people use an enema (a small liquid given into the rectum) once or twice shortly before the test to empty the lower bowel; sometimes a laxative is used instead.
- Tell the team about all your medicines, especially blood thinners (warfarin, apixaban, rivaroxaban, clopidogrel, aspirin) and diabetes medicines, and do not stop them unless you are told to.
- Tell the team about allergies, pregnancy, heart or lung conditions, or previous bowel surgery.
- You can usually eat lightly and drink as normal unless told otherwise. Follow your unit’s instructions on food and drink.
- Many people have it without sedation. If sedation is planned, arrange for an adult to take you home.
During the procedure
You lie on your left side with your knees drawn up. The doctor checks the area and gently passes the lubricated scope. Air or carbon dioxide gas is gently put in to open the bowel so it can be seen, which may cause cramping, pressure or a feeling that you need to pass stool. Slow breathing helps. The test usually takes about 10 to 20 minutes. If a small polyp or inflamed area is found, a biopsy or removal may be done; this is usually painless.
After the procedure
Most people go home soon after. You may feel wind, bloating or mild cramps for a short time; passing the gas helps. A little blood-streaking of stool after a biopsy can occur. If you had sedation, do not drive, sign legal papers or make important decisions for the rest of the day. You can usually eat and return to normal activity soon, unless told otherwise. Your doctor will explain what was seen, and biopsy results usually take a few days to a couple of weeks.
Risks
- Bloating, gas and cramping for a short time (common)
- Minor bleeding, especially after a biopsy or polyp removal (usually stops by itself)
- Rarely, a tear (perforation) in the bowel wall that may need hospital treatment or surgery
- Rarely, a reaction to sedation, if used
- Go to the emergency department promptly if, after the test, you have severe or increasing belly pain, a swollen hard belly, fever or chills, heavy bleeding or clots, black stools, dizziness or fainting.
When you get results
Alternatives if you decline
Alternatives include a full colonoscopy, which looks at the whole colon, CT colonography (a scan of the colon), stool tests for blood or inflammation, or imaging such as MRI, depending on the question. Each has pros and cons; for example, scans and stool tests cannot take biopsies. Your doctor will explain which is best for you.
Questions to ask your doctor
Save this list or print it before your appointment — doctors appreciate prepared patients.
- Why do I need this test rather than a full colonoscopy?
- How do I prepare, and do I need an enema or a laxative?
- Will I have sedation, or can I go back to work afterward?
- Do I need to adjust my blood thinners or diabetes medicines?
- When will I get results and what happens next?
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Status: Approved for publication by SGA; individual clinician review is ongoing · Published 24/04/2026
For general education only; it does not replace your doctor’s advice. Individual clinician review of this guide is ongoing. SGA clinician? Review this guide