An Information Guide 

Please read this leaflet in conjunction with Having a Colonoscopy. It will help to explain the procedure.


The procedure will be performed by a trained consultant who is experienced in specialist endoscopy techniques.


If you have any concerns or questions, the endoscopist or endoscopy nurse who assesses you before the procedure will be happy to discuss them with you.

Having an Endoscopic Mucosal Resection (EMR)

Previous tests have shown that you have a polyp in your large bowel (colon). Your doctor has advised that you should have the polyp removed by a procedure called endoscopic mucosal resection or EMR.

If you have not discussed stopping the following medications with your consultant in clinic, please ring the Endoscopy Unit immediately.

  • Ticagrelor Prasugrel Dipyridamole and Clopidogrel
  • Warfarin or acenocoumoral (Sinthrome®)
  • Dabigatran or Pradaxa®, Apixaban or Eliquis®, Rivaroxaban or Xarelto®,Edoxaban or Lixiana®
  • Non-steroidal anti-inflammatory medication like Ibuprofen and diclofenac.

This is to reduce the risk of bleeding during and after the test.

Also contact the unit if you are:

  • Diabetic
  • Have suffered a heart attack within the last 3 months
  • On kidney dialysis

What are colonic polyps?

A polyp is a small growth that sometimes forms on the lining of the bowel. Most polyps are harmless but if they are left to grow, some forms of polyps can become cancerous. By removing the polyps, your risk of developing bowel cancer is greatly reduced. Most polyps do not cause any symptoms but in some cases they may cause bleeding.

Anyone can develop colonic polyps, but certain people are more likely to get them than others. You may have a greater chance of having polyps if:

  • You are 50 years of age or older
  • You have had polyps before
  • Someone in your family has had polyps or bowel cancer
  • You are a smoker, are overweight or have a poor diet

Why have I been referred for an EMR?

Some polyps are easier to remove, but in your case, the polyp that has been found is larger than average and requires the EMR technique. This is generally considered the safest method for removing this sort of polyp.

What is EMR?

Endoscopic mucosal resection is usually carried out as part of a colonoscopy or flexible sigmoidoscopy. You will receive the standard medication for bowel preparation before your procedure and receive sedative drugs during the test. Please take time to read and follow the instructions carefully.

The EMR procedure can take longer than a standard colonoscopy but this can vary depending on the size and position of the polyp. It may only take ten minutes to remove a relatively small polyp but the procedure can sometimes take over an hour.


The polyp is identified with the colonoscope and assessed for removal by EMR.


A needle is passed through the colonoscope and inserted under the base of the polyp. Fluid is injected, producing a bleb of liquid which lifts the polyp off the lining of the bowel.


A wire snare (or lasso) is passed around the raised polyp. The lasso is pulled tight and an electric current is passed through the snare which cuts the polyp off and cauterizes any blood vessels. If the polyp is very large, it may be removed in a number of pieces in the same way.


Once the polyp has been removed, it is retrieved so that it can be sent to the pathology lab for analysis.

What are the benefits?

Removal of the polyp will reduce your risk of developing bowel cancer.

What are the risks?

EMR carries the same risks as standard colonoscopy or flexible sigmoidoscopy which are explained in the relevant leaflets. However, because of the technical nature of EMR, the risk of perforation or bleeding is slightly higher. The main risks are:

Perforation – this is a tear in the bowel wall. This occurs about once in every 50 to 100 patients (1-2%) with the highest risk when removing large polyps from the right side of your colon. Some perforations may heal without the need for surgery, but usually an emergency operation is required.

Bleeding – bleeding can occur once in every 50 to 100 patients (1-2%). The bleeding may occur immediately during the procedure but sometimes occurs up to 14 days afterwards. If bleeding does occur, it frequently stops on its own without any intervention.

However, very occasionally it requires a blood transfusion or a repeat endoscopy. Very rarely an emergency operation may be required to stop it.

Incomplete removal – sometimes the endoscopist cannot remove the entire polyp due to technical reasons. If this is the case, you may need a further attempt with endoscopy or an operation may be necessary at a later date.

Are there any alternatives to EMR?

There are two main alternatives to having an EMR:

Firstly, the polyp could be left as it is (do nothing). However, this is usually not advisable as large polyps have a higher risk of becoming cancerous over time.

Secondly, the polyp could be removed by having an operation on the bowel. This is usually a straightforward procedure but carries the risks of general anaesthetic and surgical complications. These risks may be considerably higher if you have other medical conditions.

When possible, EMR is considered to be the safest way to remove this type of polyp.

After your procedure

You will be able to rest in the recovery room until the immediate effects of the sedation have worn off. Most patients can go home the same day provided they are accompanied and have a responsible adult at home with them for that day, and overnight.

Sometimes (for example if the polyp was very large or if you live a long way away from the hospital) the endoscopist might advise that you stay in hospital overnight as a precaution. Please bring an overnight bag with you in case this is recommended.

Your results

Once you are fully awake, a doctor or nurse will provide some information regarding what was found during the procedure, the treatment that was carried out and any further tests that may be required. If you would like a friend or relative to be present, we can do this with your consent.

The polyp is usually retrieved during an EMR procedure and sent to the pathology laboratory for further analysis. It can take up to 7 to 10 days before a result is available. Sometimes, decisions about further treatment can only be made once these results are back.

Going home

If you have sedation: It is essential that a responsible adult comes to collect you from the unit. They must stay with you for 12 hours to make sure you do not have any problems. If you have no-one to stay with you, you must contact the Endoscopy booking office on the telephone number stated on your appointment letter. Once home, it is important to rest quietly. By the next day you should feel fine but sedation lasts longer than you think.

Contact numbers

If you have any questions regarding the test please ring the Endoscopy Unit at the hospital where you are going to have the test.

Royal Blackburn Teaching Hospital - 01254 733191

Burnley General Teaching Hospital - 01282 805117


If you are unable to keep this appointment, please let us know as soon as possible on the above phone numbers. This will allow us to give your appointment to another patient and rearrange another one for you.


Issue date: February 2024

Review date: February 2025