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Flexible Sigmoidoscopy
A flexible sigmoidoscopy uses a thin, bendy camera passed into the back passage to look at the lower part of the large bowel (rectum and sigmoid colon).
Quick answer
Flexible Sigmoidoscopy: what it is and what the results mean
A flexible sigmoidoscopy is an examination of the rectum and lower colon using a sigmoidoscope — a thin, flexible tube with a light and camera. Unlike a colonoscopy, it examines only the lower part of the large bowel.
- Why it is done: It is used to investigate rectal bleeding, changes in bowel habit, lower abdominal pain and diarrhoea, and to check for polyps, inflammation (such as colitis) or cancer in the lower bowel.
- Understanding results: The doctor can often tell you what was seen straight away, with biopsy results following in a couple of weeks.
What it is
A flexible sigmoidoscopy is an examination of the rectum and lower colon using a sigmoidoscope — a thin, flexible tube with a light and camera. Unlike a colonoscopy, it examines only the lower part of the large bowel.
Why it is done
It is used to investigate rectal bleeding, changes in bowel habit, lower abdominal pain and diarrhoea, and to check for polyps, inflammation (such as colitis) or cancer in the lower bowel. Small polyps can be removed and biopsies taken.
What to expect
You usually have an enema or laxative to empty the lower bowel beforehand. The tube is gently passed into the back passage while you lie on your side; air is used to open the bowel. It takes 10–20 minutes and is usually done without sedation.
Understanding the results
The doctor can often tell you what was seen straight away, with biopsy results following in a couple of weeks. Findings may include haemorrhoids, inflammation, polyps or, less commonly, cancer, guiding further tests or treatment.
Good to know
Risks and limitations
It only examines the lower bowel, so a full colonoscopy may be needed if problems are found higher up or suspected. Serious complications are rare but can include bleeding or a small tear in the bowel wall.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Flexible Sigmoidoscopy: frequently asked questions
How is this different from a colonoscopy?
A flexible sigmoidoscopy looks only at the lower part of the large bowel and needs less preparation, while a colonoscopy examines the entire colon. Your doctor chooses based on your symptoms.
Will I be sedated?
Most flexible sigmoidoscopies are done without sedation because they are quicker and less uncomfortable than a colonoscopy, but you can discuss options such as gas and air with the team.
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Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Relevant royal college / professional body
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