Gastrointestinal endoscopic mucosal resection (EMR) is a procedure to remove early-stage cancer and precancerous growths from the lining of the digestive tract.

Endoscopic mucosal resection is performed with a long, narrow tube equipped with a light and video camera. During EMR of the upper digestive tract, the doctor passes this tube (endoscope) down your throat into your esophagus, stomach or upper part of the small intestine (duodenum). To reach the colon, the doctor guides the tube up through the anus. The doctor then inserts instruments through the tube to perform the procedure.

EMR is usually done to treat a health condition. However, your doctor may also collect samples of tissue during the procedure. Examination of this tissue can help your doctor make a diagnosis. For example, if you have cancer, EMR can help determine if the cancer has spread to 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. Your doctor may recommend the procedure to remove certain early-stage cancers or precancerous growths.

Some of the conditions that EMR has been used to treat include:

  • Barrett's esophagus
  • Cancer of the small intestine (duodenum)
  • Colon polyps
  • Colorectal cancer
  • Esophageal cancer
  • Noncancerous growths of the uterus (leiomyomas)
  • Stomach (gastric) cancer

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


Risks of the endoscopic mucosal resection include:

  • Bleeding. This most common complication often can be detected and corrected during the procedure.
  • 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 is removed.
  • Narrowing of the esophagus. Removing certain esophagus lesions increases the risk of scarring that narrows the esophagus, which may lead to difficulty swallowing and require further treatment.

Call your doctor or get emergency care if you develop any of the following signs or symptoms after you have an 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 an endoscopic mucosal resection, your doctor will want to know your health history and the medications you use.

You'll be asked to provide the following information:

  • The names and doses of all prescription medications, over-the-counter drugs and dietary supplements you take — especially diabetes medications and blood-thinning drugs, including aspirin
  • Whether or not you have or ever had a drug allergy and, if so, the name of the drug
  • All medical conditions you have, especially heart disease, lung disease, diabetes and blood-clotting disorders

Food and medications

You'll receive written instructions about what to do the day before the procedure, including:

  • Fasting. You may not be able to eat or drink for many hours before the procedure. This is called fasting. Often, fasting begins at midnight before your procedure, but the specific start time can vary. You'll be instructed when to begin. You may also not be able to smoke or chew gum during this time.
  • Waiting to take certain medications. Your doctor may ask you to temporarily stop taking some medications, such as those that affect blood clotting or interfere with sedatives, before the procedure.

Other precautions

Other instructions may vary depending on the location of the lesion or lesions being removed. If the procedure involves the colon, you'll likely need to use a liquid laxative or an over-the-counter enema kit to empty your bowels and clean your colon.

What you can expect

Before the procedure

Your doctor, nurse or other health care provider will explain the risks and benefits of the procedure to you. You'll be asked to sign an informed consent document giving your doctor permission to perform the procedure. Before you sign the form, ask your doctor about anything you don't understand about the procedure.

During the procedure

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. You can expect the following:

  • Numbing medication. If the doctor will be guiding the endoscope down your throat, you may first have your throat sprayed or be asked to gargle a solution that numbs your throat. This local anesthetic makes insertion of the endoscope more comfortable.
  • Sedation. You'll receive a sedative before the procedure starts. Moderate sedation makes you feel relaxed and drowsy. You may feel slight movement or pressure during the procedure, but you shouldn't feel pain. Sometimes, heavy sedation is used. Ask your doctor 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.

There are a few versions of endoscopic mucosal resection. They are grouped into two general categories: Suction or lift method. Both require a surgical cut to remove the abnormal tissue.

After the procedure

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

You'll be advised not to do any of the following activities until the next day:

  • Drive
  • Return to work
  • Make important decisions

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

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

  • Reactions to the sedative. You may continue to feel drowsy and may have 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 have a follow-up appointment with the gastroenterologist to discuss the outcome of your endoscopic mucosal resection and the results of any laboratory tests performed on tissue samples. Questions to ask your doctor include:

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

Typically, you will have another upper endoscopy or colonoscopy several months after your procedure to be sure the entire lesion is gone. During your first procedure, your doctor may mark the area of the removed lesion with ink (tattoo) so that the area can be easily checked during any future exams. The needs for additional appointments depend on the results of these findings.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.

Aug. 31, 2017
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  3. Preparing for your upper GI endoscopy. American Gastroenterological Association. http://www.gastro.org/attachments/6515/3_UpperGIEndoscopy_Prep_Design.pdf. Accessed May 16, 2017.
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  5. Klein A, et al. How to perform high-quality endoscopic mucosal resection during colonoscopy. Gastroenterology. 2017;152:466.
  6. Odze RD, et al., eds. Gastrointestinal tract endoscopic and tissue processing techniques and normal histology. In: Odze and Goldblum Surgical Pathology of the GI Tract, Liver, Biliary Tract and Pancreas. Surgical Pathology. 3rd ed. Philadelphia, Pa.: Saunders Elsevier; 2015. https://www.clinicalkey.com. Accessed May 26, 2017.

Endoscopic mucosal resection