Mucosal resection of colorectal polyps

Colorectal polyps are growths that are found on the colon or rectum’s inner lining. While most are benign, some can develop into cancer if left untreated. Mucosal resection is a specialised, minimally invasive technique used to remove larger or potentially precancerous polyps from the bowel wall without the need for open surgery.

Mr Amyn Haji, consultant colorectal, laparoscopic surgeon and interventional endoscopist - and Europe's leading specialist in mucosal resection - answers some of the most frequently-asked questions about this procedure.

What is mucosal resection?

Mucosal resection, also known as endoscopic mucosal resection (EMR), is a technique used to safely remove polyps from the gastrointestinal lining during a colonoscopy. It is particularly useful for removing flat or broad-based polyps that cannot be easily removed with standard snare polypectomy techniques.

This procedure involves injecting a solution beneath the polyp to lift it from the underlying tissue. The raised polyp is then snared and removed in one or more pieces. EMR allows for complete removal while preserving the structure of the bowel wall.

Another advanced option for certain complex or early cancerous polyps is endoscopic submucosal dissection (ESD). ESD is a more intricate technique that allows for en bloc (single-piece) removal of larger or deeper lesions. It involves making a circumferential incision around the lesion and dissecting it carefully from the submucosal layer. Although ESD can be more time-consuming and carries a slightly higher risk of complications, it may offer more precise removal and lower recurrence rates in selected cases. It is generally reserved for high-risk or early malignant lesions that are not suitable for conventional EMR.

When is EMR recommended?

EMR is often recommended for:

• Large colorectal polyps (typically over 10 mm)
• Sessile or flat polyps that are difficult to remove in one piece
• Polyps with early signs of dysplasia (pre-cancerous changes)
• Lesions suspected of being superficial cancers, where removal can be curative

Polyps found during a screening or surveillance colonoscopy may be assessed at the same time for suitability for EMR.

How is the procedure performed?

The procedure is usually done during a scheduled colonoscopy under sedation. The steps typically include:

1. Injection of a fluid (usually saline with a dye) underneath the polyp to separate it from deeper layers of the bowel wall.
2. Snaring the lifted lesion using a wire loop attached to the endoscope.
3. Resection of the polyp in one or more pieces, depending on its size and shape.
4. Retrieval of tissue for histological analysis to check for cancer or dysplasia.

In some cases, additional techniques such as clipping may be used to close the area and reduce the risk of bleeding or perforation.

What are the benefits and risks?

EMR offers a number of advantages over surgery:

• Minimally invasive with no external incisions
• Shorter recovery time
• Day case procedure in most cases
• Preservation of normal bowel function

However, as with any procedure, there are potential risks. These include:

• Bleeding, which may occur during or after the procedure
• Perforation of the bowel wall (rare)
• Incomplete removal, especially for larger or more complex lesions

Follow-up colonoscopies are often required to monitor for recurrence or to complete removal in staged sessions.

When should you see a specialist?

If a colorectal polyp is detected, particularly one that is large or flat, a referral to a specialist with experience in advanced endoscopic techniques such as EMR may be appropriate. This ensures the most effective and least invasive approach is taken, reducing the need for surgery while allowing for accurate diagnosis and treatment.