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 larger than 2 cm and carry a higher risk of bleeding or perforation when removed.
Polyps are called complex when their size, shape or location makes removal technically difficult.
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 can be time‑consuming. Your endoscopist may ask you to return for a separate dedicated session 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. This helps reduce the risk of delayed bleeding.
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 ULTH) centre for a different procedure called Endoscopic Sub mucosal Dissection (ESD) if that was found more suitable.
All these procedures have significant complication rates and hence will be considered depending on the complexity of the individual polyp.
Before the procedure
Tell the clinical team if you take blood-thinning medicines such as warfarin, apixaban, rivaroxaban, dabigatran, edoxaban, aspirin or clopidogrel.
Please also tell us about any allergies, previous problems with sedation or anaesthetic, and any other medical conditions that may affect the procedure.
After the procedure
You may feel bloated or have mild tummy discomfort after the procedure. This usually settles within a short time.
A small amount of rectal bleeding can happen after polyp removal. However, heavy bleeding, severe pain or feeling unwell is not normal and needs urgent medical advice.
If you had sedation, you must not drive, drink alcohol, operate machinery, sign legal documents or make important decisions for 24 hours. You should arrange for someone to take you home and stay with you if possible.
When to seek urgent help
Contact the endoscopy unit or the hospital urgently if you have:
- severe abdominal pain.
- persistent or heavy bleeding from the back passage.
- large clots of blood.
- dizziness, fainting or collapse.
- fever, chills or a sudden feeling of being unwell.
If symptoms occur outside normal working hours, go to your nearest Emergency Department or call emergency services if you are seriously unwell. Please take a copy of your endoscopy report with you.
Further information is available at:
www.nhs.uk/conditions/bowel-polyps/
www.cancerresearchuk.org/about-cancer/bowel-cancer/getting-diagnosed/screening-for-people-high-risk
Useful contact numbers
For appointments and general enquiries (8.30am to 5.00pm Monday to Friday). Our booking service covers all sites so please ring any of the numbers below.
01205 445072
01476 464366
01522 573849
For procedure related enquiries (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