Endoscopic mucosal resection (EMR): what happens and what to expect

Polyps are growths on the bowel lining, and some can turn cancerous over years, so they are removed when found. Small ones are cut away during a routine colonoscopy. When a polyp is large or flat, or sits in a hard place such as a fold, standard removal is not safe or complete, and EMR is the technique that deals with it.

Alternatives are open or keyhole surgery to remove the segment of bowel carrying the polyp, or monitoring without removal, which North Tees suggests may suit someone with serious other health problems. Leeds states that leaving a polyp needs careful discussion with your consultant.

You take a strong laxative the day before so the bowel is clear; if it is not, the polyp cannot be seen properly. Leeds asks you to stop iron tablets seven days beforehand and codeine-type or anti-diarrhoea medicines three days before, while continuing other essential medicines.

Tell the endoscopy unit if you take aspirin, clopidogrel, warfarin or other anticoagulants, because they affect bleeding; Leeds lists the medicines by name and says the endoscopist will decide when you restart them. Remove nail varnish, which interferes with the oxygen monitor.

Leeds offers two comfort options. One is a sedative with a painkiller, which leaves you drowsy but not unconscious and requires an escort and 24 hours without driving, work, alcohol or signing documents. The other is Entonox, the gas and air that you control yourself, which wears off quickly and has no driving restriction but is not suitable for people with COPD or a collapsed lung.

A colonoscope is passed through the back passage. The endoscopist injects fluid beneath the polyp so it rises like a cushion, then uses a snare and diathermy to remove it. The tissue is sent for examination. Leeds says you recover for two to three hours and usually go home the same day.

North Tees quotes bleeding at about 1 in 30 and perforation at about once in every 100 patients. Leeds says bleeding is usually minimal unless you take blood-thinning medicine, can occur late, up to two weeks later, and can be treated through the colonoscope if needed. A perforation can often be closed with clips during the procedure, while rarely emergency surgery is needed.

Leeds also describes stricturing, a narrowing that can appear two weeks or more afterwards and cause difficulty passing stool, and sedation effects. Recurrence is the other issue: North Tees says polyp tissue can return in up to 20 in 100 patients within a year and that 2 to 5 in 100 end up needing surgery.

Leeds says most people have some abdominal discomfort for a few days, eased by passing wind, and can resume most medicines immediately. North Tees says minor discomfort can last about 24 hours. After sedation you should not drive or return to work that day, whereas after Entonox you may, if you feel well.

The polyp results come back within one to two weeks according to Leeds and about eight weeks in the North Tees leaflet, so ask which applies locally. North Tees schedules a repeat colonoscopy after three to six months to check the site. GOV.UK says to tell the DVLA if you cannot drive three months after an operation, though that rarely applies here.

Leeds advises seeking emergency care for severe abdominal pain not relieved by passing wind, nausea, vomiting, or fresh or altered blood from the back passage. If you feel faint, call 999. Later difficulty passing stool should be reported to your GP or endoscopy unit, and NHS 111 can help out of hours.

• Is the polyp suitable for EMR rather than surgery?

• Which sedation or Entonox option do you advise for me?

• Which of my medicines should I stop, and when do I restart them?

• When will I get the pathology result, and who will explain it?

• When will the follow-up colonoscopy be?

The technique is the same in either setting. Wherever you are treated, ask about the endoscopist's experience with large polyps, what happens if bleeding occurs after you go home, and whether the follow-up colonoscopy is included.