Flexible sigmoidoscopy
A test that uses a thin, flexible camera to look at the lower part of the bowel (the rectum and left side of the colon) to find the cause of symptoms or check for changes such as inflammation or polyps.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- It is a camera test of the lower bowel to find the cause of symptoms or check for inflammation or polyps, with biopsies and polyp removal possible during the test.
- It looks only at the lower part of the bowel, so it cannot rule out problems higher up; a colonoscopy or scan may be needed for the whole colon.
- Most people have it with no sedation or with gas and air and go home soon after; if you choose sedation you cannot drive for 24 hours and need someone to take you home.
- Some findings are explained straight away, but biopsy and polyp results usually take a few weeks; ask what the result will and will not tell you.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Looks directly at the lining of the lower bowel to find a cause for symptoms
The whole bowel needs examining, in which case a colonoscopy or scan is the right test.
You may feel cramping, bloating and wind as gas is used to open up the bowel. Biopsies and polyp removal are usually usually not painful.
Clear written advice on warning signs of bleeding or perforation and who to contact.
You may feel cramping, bloating and wind as gas is used to open up the bowel. Biopsies and polyp removal are...
You rest until the gas settles and any cramping eases. Without sedation, many people can leave fairly soon; with...
Some findings are explained before you leave. If you had sedation, do not drive, work, drink alcohol or sign...
Biopsy and polyp results are usually sent to you or discussed at a follow-up, with advice on any further tests or...
What is a flexible sigmoidoscopy?
A flexible sigmoidoscopy is a test that lets a clinician look directly at the lining of the lower bowel, meaning the rectum and the left side of the colon, using a thin, bendy tube with a camera and light on the end.
It is used to find the cause of symptoms such as bleeding from the bottom, a change in bowel habit or lower tummy pain, and to look for inflammation (such as colitis) or growths (polyps). Small samples (biopsies) can be taken and many polyps can be removed during the test.
It looks only at the lower part of the bowel. It does not see the whole colon, so it cannot rule out problems higher up; a colonoscopy or a scan may be needed for that. Because it examines a shorter length, the bowel preparation is usually simpler, often just an enema, rather than the full preparation needed for a colonoscopy.
A normal test is reassuring about the area examined, but no test is perfect, and it cannot guarantee that nothing will ever develop. Your clinician will explain what your result means and whether any further test is needed.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Flexible sigmoidoscopy vs colonoscopy
| Point | Flexible sigmoidoscopy | Colonoscopy |
|---|---|---|
| Area seen | Lower bowel only | Whole large bowel |
| Preparation | Usually an enema | Full bowel preparation (laxatives) |
| Sedation | Often none or gas and air | More often sedation |
| Time | Often shorter | Usually longer |
Which test you need depends on your symptoms and what needs to be looked at. A flexible sigmoidoscopy does not replace a colonoscopy when the whole bowel needs examining.
Preparing for your procedure
- Follow the bowel preparation instructions exactly; for many people this is a single enema given a few hours before the test, often at home.
- Ask whether you can eat and drink normally; this depends on the preparation you are given.
- Tell the unit about all medicines, especially blood thinners, diabetes medicines and iron tablets, as some need adjusting beforehand.
- Tell them if you are or might be pregnant, or have a pacemaker or other implant, as this can affect the test.
- Decide in advance about pain relief or sedation; if you choose sedation, arrange for someone to take you home and stay with you.
- Wear comfortable clothing and expect to change into a gown for the test.
- Plan no driving, work, alcohol or signing important documents for 24 hours if you have sedation.
What happens
After the bowel preparation, you change into a gown and lie on your left side. The clinician gently passes the thin, flexible tube through the back passage into the lower bowel. Some air or gas is used to open up the bowel so the lining can be seen clearly, which can cause cramping and a feeling of wind.
You may be offered nothing, gas and air (Entonox) to breathe, or sedation through a vein, depending on the unit and your choice. The clinician looks at the lining on a screen, and can take small biopsies or remove polyps usually not painfully during the test.
The test itself often takes about 10–20 minutes, though times vary. Afterwards you rest until any gas settles, and longer if you have had sedation. Many people without sedation can leave fairly soon.
Is this procedure right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- The whole bowel needs examining, in which case a colonoscopy or scan is the right test.
- There is a known or suspected bowel perforation or severe active inflammation where the test could be unsafe.
- The person is too unwell or unable to have the test safely without stabilising first.
- Symptoms point to a problem higher in the bowel that this test cannot reach.
Delay or rearrange if…
- There is an active severe flare of bowel inflammation where the test could be risky.
- You are or might be pregnant and the test is not urgent.
- Blood thinners or diabetes medicines have not been reviewed before a planned polyp removal.
- The bowel preparation has not been done, so the view would be poor.
- You are acutely unwell and need assessment first.
Alternatives to discuss
- Colonoscopy when the whole large bowel needs examining.
- CT colonography (a scan of the bowel) in some situations.
- A stool test such as a FIT test as part of assessing symptoms.
- Watchful waiting with safety-netting for very mild symptoms in selected cases.
- Treating a clear, simple cause (such as piles) first where appropriate, with review.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Looks directly at the lining of the lower bowel to find a cause for symptoms
- Can detect inflammation, polyps and other changes in the area examined
- Allows biopsies and removal of many polyps during the same test
- Usually needs simpler preparation than a colonoscopy
- Can often be done without sedation, so many people recover quickly
- A clear result can be reassuring about the part of the bowel examined
Risks & complications
- Cramping, bloating and a feeling of wind during and after the test
- A small amount of bleeding from the bottom, especially if a biopsy was taken or a polyp removed
- Temporary discomfort as the tube is passed
- Feeling drowsy for the rest of the day if you have sedation
- Bleeding that is heavier or lasts longer, particularly after polyp removal
- A missed area or finding, because the test sees only the lower bowel and no test is perfect
- Reaction to sedation, such as low blood pressure or slowed breathing
- Needing a further test, such as a colonoscopy or scan
- A tear (perforation) of the bowel wall, which may need surgery
- Significant bleeding needing admission or a procedure
- Infection
- A serious reaction to sedation
Serious complications are rare. The most important are bleeding and a tear (perforation) of the bowel, which are more likely if a polyp is removed. NHS information often quotes a small risk of bleeding or perforation of around 1 in 5,000 for the test overall, and large screening series report perforation in only a few per 100,000. Remember that a normal result reassures about the area examined but cannot rule out problems higher up or guarantee the future. Ask what your result changes and whether any further test is needed.
Published figures to discuss
Complication rates are low and depend on whether a polyp is removed, the person's health and medicines such as blood thinners. Reported figures vary between units and screening programmes, so the ranges below are cautious and approximate.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Bleeding or perforation overall | Small; NHS information often quotes around 1 in 5,000 for the test | Higher if a polyp is removed; figures vary between sources and units. | CUH — Flexible sigmoidoscopy with enema bowel preparation (patient information)cuh.nhs.ukPublished figure |
| Perforation in screening series | Only a few per 100,000 in large screening studies | Diagnostic tests without polyp removal carry a lower risk than therapeutic ones. | CUH — Flexible sigmoidoscopy with enema bowel preparation (patient information)cuh.nhs.ukPublished figure |
| Need for a further test | Varies by indication | A colonoscopy or scan may be needed to examine the whole bowel or clarify a finding. | Guide sourcesClinical context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is usually no physical recovery beyond waiting for any gas and cramping to settle. If you have sedation, you will need longer to recover and someone to take you home. The main thing to wait for is your results.
- Cramping, bloating and passing wind for a short time after the test
- A small amount of bleeding from the bottom, especially after a biopsy or polyp removal
- Feeling drowsy for the rest of the day if you had sedation
- Waiting a few weeks for biopsy or polyp results
Aftercare
- Pass wind freely afterwards to relieve bloating and cramping.
- Eat and drink normally once you feel ready, unless told otherwise.
- If you had sedation, rest at home, do not drive or work, and avoid alcohol and important decisions for 24 hours.
- Restart any medicines, including blood thinners, only as advised, especially if a polyp was removed.
- Expect a small amount of bleeding from the bottom, but seek advice if it is heavy or persistent.
- Know who to contact and what to watch for in case of bleeding or severe pain.
- Make a note of any results explained on the day, as sedation can affect memory.
- Bowel preparation (enema) understood and done as instructed
- Decision made about sedation or gas and air
- Someone to take you home and stay with you if you have sedation
- Day off arranged if you are having sedation
- List of medicines, especially blood thinners, ready to discuss
- Unit contact number saved in case of problems afterwards
⚠ Get urgent help if…
- Severe or worsening tummy pain after the test
- A hard, swollen or very tender tummy
- Heavy bleeding from the bottom or passing a lot of blood or clots
- Black, tarry stools
- A high temperature, chills or feeling very unwell
- Feeling faint, dizzy or breathless
- Vomiting blood — seek urgent help
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
Some findings, such as visible inflammation or polyps, can often be explained straight after the test, though sedation may affect what you remember. Biopsy and polyp results usually take a few weeks and are sent to you or discussed at a follow-up.
A normal or clear result is reassuring about the lower bowel that was examined. It cannot rule out problems higher up in the colon, which the test does not reach, and no test is perfect, so a small change can occasionally be missed. Your clinician will explain what your result means and whether any further test, such as a colonoscopy or scan, is needed.
How long a result stays useful depends on why the test was done. A clear result for current symptoms does not mean you never need checking again, especially if symptoms change or return. For people with polyps or a bowel condition, repeat tests are planned on a schedule. If new or worsening symptoms develop, you should be reassessed rather than relying on an old result.
Related tests, treatments or support
A flexible sigmoidoscopy is sometimes done alongside other tests, such as blood tests, a stool test (like a FIT test) or imaging, to build a fuller picture. If the whole bowel needs examining, a colonoscopy may be arranged instead of, or in addition to, this test.
Follow-up & long-term care
Findings seen during the test are usually explained on the day, and biopsy or polyp results follow over a few weeks, by letter or at a follow-up appointment. If a polyp was removed or a condition found, you will be told about any treatment, further tests or a plan for repeat surveillance.
- Attend any planned repeat or surveillance tests on schedule
- Report new or changing bowel symptoms rather than waiting
- Keep up with bowel screening invitations when offered
- Follow advice on stopping and restarting blood thinners around the test
Repeat, follow-on and what comes next
- If preparation is poor or views are limited, the test may need repeating.
- A finding in the lower bowel may lead to a colonoscopy to check the rest of the bowel.
- Biopsy or polyp results can be inconclusive and need repeat sampling or further tests.
- Surveillance tests may be planned at intervals for polyps or bowel conditions.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Clear written advice on warning signs of bleeding or perforation and who to contact.
- A defined process and timescale for biopsy and polyp results.
- Advice on restarting blood thinners, especially after polyp removal.
- Clear sedation aftercare, including the 24-hour rules and the need for an escort.
- A plan for any further test, such as a colonoscopy, if needed.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- Whether biopsies are taken or polyps removed during the test
- Whether you choose sedation, which may add monitoring and recovery time
- Laboratory analysis of any biopsies or polyps
- The endoscopist's fee and the unit or facility fee
- A follow-up appointment to discuss results
- Whether a further test, such as a colonoscopy, is then needed
- The endoscopist's fee and the unit or facility fee
- Bowel preparation (enema) and any sedation included
- Laboratory testing of biopsies or removed polyps
- A follow-up appointment to discuss results
- What happens, and any extra cost, if a polyp is found and removed
- What happens if the test is inconclusive or a further test is needed
On the NHS? Flexible sigmoidoscopy is commonly available on the NHS to investigate symptoms. It is no longer part of routine bowel-cancer screening, which now uses a home FIT kit every 2 years with a colonoscopy offered after an abnormal result; private testing may be used for speed or choice when not urgent.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Implying a normal lower-bowel test rules out all bowel disease, including higher up.
- Not explaining the 24-hour driving and decision-making rules if sedation is chosen.
- Not discussing the higher bleeding risk if a polyp is removed and how blood thinners are managed.
- Not making clear who sees the results and when they will be available.
- Not setting out warning signs of perforation or significant bleeding.
Marketing red flags
- Promoting the test as able to 'rule out bowel cancer' when it does not examine the whole bowel.
- Describing it as completely pain-free or without risks.
- Not mentioning sedation rules or recovery and driving restrictions.
- Offering it as a one-size-fits-all alternative to colonoscopy regardless of symptoms.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- Is a flexible sigmoidoscopy the right test for my symptoms, or do I need a colonoscopy?
- What pain relief or sedation can I have, and what are the trade-offs?
- Will you take biopsies or remove polyps during the test if needed?
- What will this result change, and what happens if it is normal, abnormal or unclear?
- How should I manage my blood thinners and other medicines around the test?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my procedure, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this procedure not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Is a flexible sigmoidoscopy available on the NHS?
Does it hurt?
Do I need the full bowel preparation like a colonoscopy?
Can I drive home afterwards?
When will I get my results?
Does a normal result mean my bowel is completely healthy?
How does NHS bowel cancer screening work now?
Find a verified specialist for flexible sigmoidoscopy
Every consultant is GMC-checked and independently reviewed. Search by postcode and distance, or switch to a map. Ordered by rating, relevance and recency — never by who pays.
No verified consultants list this procedure yet — browse the full directory.
How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: British Society of Gastroenterology — clinical resources and guidelines JAG — Guide to meeting endoscopy quality and safety standards CUH — Flexible sigmoidoscopy with enema bowel preparation (patient information) Flexible sigmoidoscopy — NIDDK (NIH) Colorectal cancer incidence and mortality with screening flexible sigmoidoscopy (NEJM) NHS bowel cancer screening programme — England overview (GOV.UK) Bowel screening — Scotland (NHS inform) Bowel screening — Wales (Public Health Wales) Bowel cancer screening — Northern Ireland (nidirect)
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
Related guides: Banding of haemorrhoids · Haemorrhoidal artery ligation (HALO) · Anal fissure treatment · Anal fistula surgery · Appendix removal