The removal of a polyp is called a polypectomy and can be achieved by using a variety of instruments through channels of the endoscope. If a polyp is found on the left side of your bowel, there is a higher chance of you having polyps on the right side of your bowel. 

As a flexible sigmoidoscopy does not reach the right side of your bowel, you may be asked to return on another day for a full colonoscopy if a polyp is found. A colonoscopy allows the entire large bowel to be examined and any further polyps to be removed.

Polypectomy Surgery

For most polyps, a snare (wire lasso) is placed around the polyp base and tightened while an electric current is passed. This cuts through the polyp and cauterizes any blood vessels to prevent bleeding.

Flat or very large polyps are more difficult to remove. Sometimes large flat polyps are removed by a technique called EMR (Endoscopic Mucosal Resection). This involves injecting liquid into the lining of the bowel underneath the polyp. This raises a bleb under the polyp, lifting it off the lining of the bowel and allows the wire loop snare to capture the polyp.

For very small polyps, special forceps (graspers) can be used to hold the polyp while the diathermy current is applied to destroy the tissue.

The endoscopist will try to retrieve the polyp tissue once it has been removed so that it can be analyzed under the microscope in the pathology lab.

After the procedure

You will be escorted to the recovery area and allowed to rest for as long as is necessary. If you received sedation, your oxygen levels, blood pressure and heart rate would be recorded. It usually takes about 30 minutes for the initial effects of sedation to wear off, but some people may feel fully alert immediately after the procedure. However, the drugs remain in your blood system for about 24 hours, and you can intermittently feel drowsy with lapses of memory. You will need someone to escort you home and supervise you for this 24-hour period.

If you received Entonox gas during the procedure, its effects usually wear off within a few minutes. You will be observed in the department until you feel back to your normal self. Before you leave the department, the nurse or doctor will explain the findings of your flexible sigmoidoscopy and any medication or further investigations required. He or she will also inform you if you require further appointments. If biopsies were taken, they would need to be sent to the pathology lab for further analysis. It may take up to a fortnight for these results to be available.


As with most medical procedures, there are some risks involved. Your doctor will have felt that the benefits of this procedure outweigh the potential risks before he/she suggested that you should have it carried out.

You may experience bloating and abdominal discomfort for a few hours after the procedure because air is used to inflate the bowel. This can often be relieved by passing wind at the back passage.

If you choose to receive sedative drugs, they can cause your breathing to slow down or result in a fall in your blood pressure. This is the reason we do not give high doses of the drugs for the procedure. We monitor your breathing and oxygen levels carefully throughout the procedure, and this rarely becomes a problem. In any case, an antidote to the sedative drugs that we use is always available, and this can reverse its effects immediately.

The most significant risks of sigmoidoscopy are:

  • Perforation (or a tear of the lining of the bowel),
  • Bleeding.

The risk of perforation is less than 1 for every 15,000 procedures performed but may be higher if a polyp is removed.

If the bowel preparation drugs have not worked very well and there is still stool in your bowel, it can hide abnormalities that can be missed.

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