At a glance
A flexible sigmoidoscopy is a common procedure that allows a doctor to directly examine the rectum and lower colon using a thin, flexible camera tube. It is used to investigate symptoms, screen for conditions, and sometimes treat issues found during the examination.
It is less extensive than a colonoscopy, requires simpler preparation, and is usually done without sedation. Most people find it manageable, and it provides important diagnostic information.
Why it is done
A sigmoidoscopy may be recommended to:
- Investigate rectal bleeding — to identify the source
- Assess bowel changes — persistent change in bowel habits
- Screen for polyps or cancer — particularly in bowel cancer screening programmes
- Evaluate inflammation — suspected IBD, proctitis, or colitis
- Follow up on previous findings
- Assess conditions that affect the lower bowel and rectum
Preparation
The enema
The main preparation is usually a self-administered enema, done one to two hours before the procedure. The enema clears the lower bowel to give the doctor a clear view.
- You will be given an enema kit with instructions
- It is used at home or at the clinic, depending on the arrangement
- It works within 15 to 30 minutes
- You will need access to a toilet during this period
Diet
- Some clinics ask you to eat lightly the day before
- You may be asked to avoid high-fibre foods or red/purple foods that could obscure the view
- Clear fluids are usually fine
- Specific instructions vary — follow the guidance from your clinic
On the day
- Wear comfortable, loose clothing
- Eat a light breakfast if instructed (or nothing if told to fast)
- Arrange transport if you think you may feel unwell afterwards, though most people are fine to travel independently
- Allow about an hour for the appointment
What happens during the procedure
Before
- You change into a gown
- A nurse or doctor explains the procedure and obtains consent
- You may be offered Entonox (gas and air) for comfort — this is optional
- Sedation is usually not needed but may be available if you prefer
The examination
- Positioning — you lie on your left side with knees drawn up
- Lubrication and insertion — the scope is lubricated and gently inserted through the anus
- Advancement — the scope is slowly advanced through the rectum and into the sigmoid colon
- Air inflation — a small amount of air is pumped in to gently inflate the bowel, providing a better view. This may cause a bloating or cramping sensation
- Examination — the doctor examines the bowel lining on a screen as the scope is withdrawn
- Biopsies — if needed, small tissue samples can be taken painlessly through the scope
- Withdrawal — the scope is slowly removed
How it feels
- Pressure — as the scope is inserted and advanced
- Bloating or cramping — from the air used to inflate the bowel
- An urge to open the bowels — this is normal and expected
- Brief discomfort at certain points as the scope navigates bends in the colon
- Generally tolerable — most people describe it as uncomfortable but manageable
After the procedure
- You can get dressed and leave fairly quickly
- Some bloating and wind is normal for a few hours — the air introduced during the procedure passes naturally
- You can eat and drink normally
- Light cramping may persist briefly
- If biopsies were taken, you may notice slight bleeding — this is normal
- Results of biopsies typically take one to two weeks
Returning to normal
- Most people resume normal activities the same day
- If you had sedation (unusual for sigmoidoscopy), you will need someone to take you home and should rest for the day
- There are no lasting restrictions
What the doctor may find
Common findings include:
- Hemorrhoids — internal hemorrhoids are often visible
- Polyps — small growths that may be benign but can be removed for testing
- Inflammation — signs of proctitis, colitis, or other inflammatory conditions
- Normal findings — often the most common result, which is reassuring
- Fissures or other conditions — visible in the lower canal
Tips from people who have had one
- The anticipation is worse than the reality — the most consistent feedback
- Breathe through the uncomfortable moments — deep breathing helps
- The air is the most uncomfortable part — it passes within hours
- It is over quickly — most people are surprised by how brief it is
- Ask questions — understanding what is happening reduces anxiety
- It is worth doing — the information it provides is valuable for managing your health