Date Updated: 01/09/2021


Gastrointestinal endoscopic mucosal resection (EMR) is a procedure to remove precancerous, early-stage cancer or other abnormal tissues (lesions) from the digestive tract.

Endoscopic mucosal resection is performed with a long, narrow tube equipped with a light, video camera and other instruments. During EMR of the upper digestive tract, the tube (endoscope) is passed down your throat to reach an abnormality in your esophagus, stomach or upper part of the small intestine (duodenum).

To remove lesions from the colon, the tube is guided up through the anus.

Primarily a treatment procedure, EMR is also used to collect tissues for diagnosis. If cancer is present, EMR can help determine if the cancer has invaded tissues beneath the digestive tract lining.

Why it's done

Endoscopic mucosal resection is a less invasive alternative to surgery for removing abnormal tissues from the lining of the digestive tract. These tissues may be:

  • Early-stage cancer
  • Precancerous lesions, which may become cancerous

Endoscopic mucosal resection is usually performed by a specialist in digestive system disorders (gastroenterologist) who has expertise in this technique.


Risks of the endoscopic mucosal resection include:

  • Bleeding. This most common complication often can be detected and corrected during the procedure.
  • Narrowing of the esophagus. Removing a lesion that encircles the esophagus carries some risk of scarring that narrows the esophagus, a condition that may lead to difficulty swallowing and require further treatment.
  • Puncture (perforation). There is a slight risk of a puncture through the wall of the digestive tract, depending on the size and location of the lesion that's removed.

Call your doctor or get emergency care if you develop any of the following signs or symptoms after undergoing endoscopic mucosal resection:

  • Fever
  • Chills
  • Vomiting
  • Black stool
  • Bright red blood in the stool
  • Chest or abdominal pain
  • Shortness of breath
  • Fainting

How you prepare

Before you have endoscopic mucosal resection, you'll be asked to provide the following information:

  • All prescription medications, over-the-counter drugs and dietary supplements you take — particularly diabetes medications and blood-thinning drugs, including aspirin — and their doses
  • Drug allergies
  • All medical conditions, including heart disease, lung disease, diabetes and blood-clotting disorders

Your doctor may ask you to temporarily stop taking some medications, including those that affect blood clotting or those that interfere with sedatives before the procedure.

You'll receive written instructions about what to do the day before the procedure. These instructions may vary depending on the location of the lesion or lesions being removed. In general, the instructions will likely include:

  • Fasting. You'll be instructed when to begin fasting. You may not be able to eat, drink, chew gum or smoke after midnight before the procedure. You may be asked to be on a clear liquid diet the day before your procedure.
  • Cleaning the colon. If the procedure involves the colon, you'll likely use a liquid laxative or an over-the-counter enema kit to empty your bowels and clean your colon.

You'll also sign an informed consent document giving your doctor permission to perform the procedure after the risks and benefits have been explained to you. Before you sign the form, ask your doctor about anything you don't understand about the procedure.

Travel arrangements

You'll likely go home the day of your EMR. However, because of sedation used during the procedure, you'll need to have someone take you home.

What you can expect

There are a few versions of endoscopic mucosal resection. Ask your gastroenterologist about how your procedure will be performed. A common approach includes these steps:

  • Inserting the endoscope and guiding the tip to the area of concern
  • Injecting a fluid under a lesion to create a cushion between the lesion and healthy tissue underneath it
  • Lifting the lesion, possibly using gentle suction
  • Cutting the lesion to separate it from surrounding healthy tissue
  • Removing the abnormal tissue from your body
  • Marking the area with ink (tattoo) so that it can be found again with future endoscopic exams

During the procedure

During an endoscopic mucosal resection, you can expect the following:

  • Your role. You'll be asked to change into a gown before the procedure. During the procedure, you'll lie on your side on a cushioned table.
  • Local anesthetic. If the endoscope is inserted through your throat, you may have your throat sprayed or be asked to gargle a solution to numb your throat to make insertion of the endoscope more comfortable.
  • Sedation. You'll be sedated during the procedure. With moderate sedation that causes you to be relaxed and drowsy, you may feel slight movement or pressure during the procedure, but you shouldn't feel pain. Or you may be heavily sedated. Discuss with your gastroenterologist which option is appropriate for you.
  • Monitoring. Nurses or other professionals will monitor your heart rate, blood pressure, blood oxygen level and comfort while the doctor performs the procedure.

After the procedure

You'll remain in a recovery room until most of the effect of the sedative has worn off. You'll receive written instructions about when you can start eating and drinking and when you can resume normal activities.

Relatively mild side effects may occur within 24 hours after the procedure including:

  • Reactions to the sedative. You may continue to feel drowsiness and may experience nausea and vomiting.
  • Sore throat. If the endoscope was guided down your esophagus, your throat may be sore.
  • Gas or cramps. If air was pumped into your digestive system to make it more accessible, you may have gas, bloating or cramps after the procedure.

You'll also receive written instructions about when to call your doctor or get emergency care after the procedure. The following signs or symptoms may indicate a serious complication from endoscopic mucosal resection:

  • Fever
  • Chills
  • Vomiting
  • Black stool
  • Bright red blood in the stool
  • Chest or abdominal pain
  • Shortness of breath
  • Fainting


You'll likely have a follow-up appointment with the gastroenterologist to discuss the outcome of your endoscopic mucosal resection and laboratory tests performed on lesion samples. Questions to ask your doctor include:

  • Were you able to remove all abnormal tissues?
  • What were the results of the laboratory tests? Were any of the tissues cancerous?
  • Do I need to see a cancer specialist (oncologist)?
  • If the tissues are cancerous, will I need additional treatments?
  • How will you monitor my condition?

Follow-up exams

Typically, a follow-up exam is performed three to 12 months after your procedure to be sure the entire lesion was removed. Depending on the findings, your doctor will advise you about further examinations.

An exam will likely include a visual inspection with the use of an endoscope. Your doctor may mark the area of the removed lesion with ink (tattoo) so that when follow-up endoscopy is performed, he or she can be sure the lesion was removed completely.

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