How is sigmoidoscopy different from colonoscopy?

Sigmoidoscopy checks only the lower part of the large bowel, needs just an enema to prepare and is usually done without sedation. Colonoscopy checks the whole large bowel and needs full bowel preparation and sedation.

Most people feel some pressure, cramping or a need to pass wind, but not real pain. Tell the team if you are uncomfortable; sedation is available if needed.

Can I go to work afterwards?

Yes, if you did not have sedation. Most people carry on with their day straight away.

I think I just have piles. Why do I need this test?

Piles are a common cause of bleeding, but other conditions can cause the same symptoms. Sigmoidoscopy confirms the cause, so you get the right treatment.

Test or procedure

Sigmoidoscopy

A flexible sigmoidoscopy checks the rectum and the lower part of the large bowel with a short, flexible camera. It is quicker than a colonoscopy, needs only a small enema to prepare, and is usually done without sedation.

A clean, prepared procedure room with an endoscopy tower beside the bed.

Duration10–15 minSedationUsually none

What it is

A sigmoidoscope is a thin, flexible tube with a light and a camera at its tip, shorter than a colonoscope. It is passed gently through the back passage to look at the rectum and the sigmoid colon, the lower part of the large bowel where many problems causing bleeding start. Dr. Tumma can see piles, fissures, inflammation, polyps and growths, and take small tissue samples (biopsies). It does not check the whole bowel, so a full colonoscopy may still be advised in some cases.

Why it is done

Fresh blood in the stools or bleeding from the back passage
Checking whether bleeding is from piles or a fissure, or from something higher up
Pain, itching or a lump around the back passage
A change in bowel habit where the doctor wants a quick first look
Checking or following up colitis affecting the lower bowel

Before: how to prepare

The preparation is lighter than for a colonoscopy: usually just a small enema given at the clinic, or at home as instructed, before the test.
You can usually eat a light meal on the day. We will tell you if you need to fast.
Bring a list of your medicines. Tell us if you take blood thinners or aspirin, in case a biopsy is needed; do not stop them on your own.
Bring any previous colonoscopy, sigmoidoscopy or biopsy reports.
If you choose sedation, come with an adult who can take you home.

Printable preparation guidePreparing for your colonoscopy. Day-by-day steps, food lists and medicines to ask about.Read more

On the day

Enema
A small enema is given to clear the lower bowel. You empty your bowel a few minutes later.
Getting ready
You change into a gown and lie on your left side with your knees drawn up.
The test
The scope is passed gently into the rectum and lower bowel. A little air is used to open the bowel, which may cause some cramping or a feeling of needing the toilet.
Biopsies, if needed
Small samples may be taken. You do not feel this.
Findings
The doctor explains what she saw straight away, and you can usually go home soon after.

After

You can usually return to normal activities, food and work straight away.
Some bloating and wind for a few hours are normal; passing the air relieves it.
A small streak of blood can appear after a biopsy.
If you had sedation, do not drive, operate machinery or sign important documents for the rest of the day.
Call us or go to the nearest emergency if you have heavy bleeding, severe tummy pain, a swollen, hard tummy or fever.

Results. Dr. Tumma tells you what she saw right after the test. If biopsies were taken, they go to a lab and results usually take a few days. If anything needs a fuller look, she may advise a colonoscopy.

Risks, explained honestly

Common and mild

Cramping and bloating for a short time
A little spotting of blood after a biopsy

Rare but serious

Bleeding that needs treatment
A tear (perforation) in the bowel wall, which is rare but serious and may need surgery
A problem higher up in the bowel can be missed, because only the lower part is checked