Information regarding large or complex polypectomy during colonoscopy or flexible sigmoidoscopy

Polyps are a wart like overgrowth of cells arising from the lining of the large bowel. Large polyps are those that measure more than 2cm in size and carry a higher risk of bleeding or perforation when removed.

What are large or complex polyps?

Polyps are a wart like overgrowth of cells arising from the lining of the large bowel. Large polyps are those that measure more than 2cm in size and carry a higher risk of bleeding or perforation when removed.

Some polyps are called ‘complex’ because of their location or difficult position.

Polyps in the right side of the large bowel have a higher risk of perforation (hole in the bowel) during resection due to the thin bowel wall.

Polyps that have a thick stalk have a higher risk of bleeding due to the likelihood of a large blood vessel in the stalk.

Large polyps with no stalk (sessile polyps) also have a higher risk of bleeding and perforation.

Polyps found very close to a diverticulum (out-pouching of the lining of the bowel due to muscle weakness resulting from wear and tear), appendix orifice or ileo-caecal valve (valve at the junction of large and small bowel) have a higher risk of perforation.

How are large or complex polyps removed?

Large or complex polyps are sometimes removed by a technique called Endoscopic Mucosal Resection (EMR). This involves injecting a solution into the bowel wall, between the lining and the muscle layer, to raise the polyp away from the muscle layer of the bowel. This separation reduces the risk of perforation by protecting the muscle layers.

Some large, flat polyps might have to be removed in small pieces (piecemeal EMR) using snare with heat treatment followed by snare without heat (cold snare technique) to any tiny remaining pieces of polyp tissue.

Resection of a complex polyp may be time consuming and your endoscopist may choose to do this procedure on a separate dedicated session, requiring you to attend for a repeat test, on another day. Occasionally, your endoscopist may advise an overnight admission to the hospital, for observation following a complex polyp removal, particularly in the event of any complications.

Following polyp removal, it is advised that you avoid any heavy lifting or strenuous exercise for approximately 2 weeks.

What are the risks of large or complex polyp removal?

The bleeding risk following a large or complex polypectomy may be as high as 1 in 50 procedures and the risk of perforation could be as high as 1 in 100 procedures depending on the size, location and the nature of the polyp. Precautions are taken before, during and after the procedure in the form of applying clips, cauterising any blood vessels or applying a constricting loop around the removal site, although in a small number of cases, surgery (requiring stoma formation) and blood transfusion may still be required. There is a very small chance of being admitted to the intensive care unit if you experience life threatening complications from the procedure.

What are the alternatives and how will I be able to decide if I want to go ahead with the procedure?

The alternative options could include the removal of the polyp or a segment of the bowel by an operation. This would carry the risks of the operation and the anaesthetic. There are risks and benefits to this, depending on the individual situation and if you have any queries you can discuss this with your consultant. We will do our best to help you make the right decision for you, prior to undergoing any procedure. We may refer you to a tertiary (outside ULHT) centre for a different procedure called Endoscopic Sub mucosal Dissection (ESD) if that was found more suitable.

All of these procedures have significant complication rates and hence will be considered depending on the complexity of the individual polyp.

Further information is available at:

Contact information

If you have any further queries then please contact one of the telephone numbers listed below:

8.30am to 6.00pm Monday to Friday

Boston                        01205 446559

Grantham                  01476 464085

Lincoln                       01522 573016

Louth                          01507 631236

All Bowel Cancer Screening Programme queries:

Telephone: 01522 597548

NHS Bowel Cancer Screening Programme and ULHT Endoscopy Units