Endoscopic mucosal resection (EMR)

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was reviewed on April 28, 2022.

An endoscopic mucosal resection (EMR) is a procedure that involves inserting a thin, lighted instrument with a camera into the digestive tract to locate and remove abnormal or cancerous growths. The device used, called an endoscope, is a hollow tube through which a doctor passes the surgical tools needed to remove the growth. The tube is inserted through your mouth and down your throat to diagnose and treat cancers in the esophagus, stomach or upper intestine. For cancers in the colon (lower intestine), the endoscope is inserted through the anus.

EMRs are performed by doctors trained and experienced in endoscopic procedures. Often, the doctor is a gastroenterologist, an expert in diagnosing and treating problems in the digestive tract.

An EMR isn’t the same as an endoscopic biopsy, in which only a small amount of abnormal tissue is removed for testing. The resection procedure allows doctors to remove growths entirely, potentially treating some cancers without the need for more aggressive surgery. These might include precancerous growths, such as the ones that form in the condition called Barrett’s esophagus, or early-stage gastrointestinal cancers, such as cancer in the stomach.

The growths are sent to a laboratory for testing and analysis just as biopsies are, yet they often provide a more reliable and comprehensive diagnosis than smaller biopsy samples. At the lab, diagnostic experts called pathologists perform tests on the specimens and examine them under a microscope to determine the exact type of cancer and whether it’s likely to spread, among other factors.

The EMR was initially designed as a potential treatment option for early-stage stomach cancer by doctors in Japan, where stomach cancer is particularly prevalent. In the United States, stomach cancers are usually not diagnosed until they’re more advanced because screening tests aren’t routine. As a result, EMRs aren’t used as frequently here, so doctors who do perform the procedure must have expert knowledge and experience.

When you may need an EMR

Beyond stomach cancer, EMR is now an option for various early-stage cancerous or precancerous growths in the gastrointestinal tract, including those that form in the:

  • Esophagus
  • Small intestine
  • Colon
  • Rectum

An EMR is most appropriate for cancers or precancers contained within the innermost lining of the gastrointestinal tract called the mucosa, which gives the procedure part of its name. Digestive cancers often start in this inner layer, but they can grow to invade deeper layers over time. If this happens, it can metastasize (spread) to other parts of the body. This procedure is generally used only for cancers within the mucosa because it’s difficult to extract larger tumors without performing actual surgery. Also, if cancer cells are suspected to be present in deeper layers of the gastrointestinal lining, the removal of superficial growths through EMR may not provide much benefit.

The layer directly beneath the mucosa is called the submucosa. Some cancers that have grown beyond the mucosa and into the submucosa can still be treated endoscopically and with a similar technique called endoscopic submucosal dissection (ESD). Like the EMR, an ESD procedure involves an endoscope being inserted into the mouth or anus, but the tools used to extract the growth can go deeper into the gastrointestinal lining and remove more tissue than those used for EMRs.

How to prepare for an EMR

If you require an EMR, your doctor will tell you the steps you need to take in advance. Your doctor will likely ask about your medical history, allergies, and which medications or supplements you take. If you’re taking anything that could increase the risk of complications or interfere with the procedure, your doctor may recommend that you stop taking it or adjust your dose. For example, you may be told to stop taking painkillers that contain codeine or supplements that contain iron.

Your doctor can also tell you if you need to adjust your diet or fluid intake before the procedure. Typically, patients are told not to eat or drink anything starting about eight hours before the EMR. For an EMR in the lower gastrointestinal tract, you’ll need to adhere to a liquid diet and take steps to clear the bowels before the procedure. Your doctor will provide more specific instructions depending on your circumstances.

Plan to arrange for a ride home after the procedure. During an EMR, you’ll be given sedatives to keep you relaxed, and these medications take time to wear off. To be safe, you will be advised not to drive for 24 hours after the procedure.

What to expect from an EMR

The procedure is usually performed in a hospital or outpatient center, and it can take between 30 minutes and an hour (or more). Your entire appointment may last up to four to five hours, including a one- to two-hour stay after the procedure.

When it’s time to start the procedure, you will likely be given medication to make you drowsy and comfortable through a needle in your arm. You may also be given a painkiller. Some patients receive general anesthesia to put them in a deep sleep. For an EMR of the upper gastrointestinal tract, doctors may use a throat-numbing spray to prevent gagging.

Once you’re sedated, your doctor will insert the endoscope and pass it through to the area of concern, such as the stomach or colon. The camera attached to the endoscope will send video back to a monitor in the room, allowing your doctor to view the area. Once your doctor locates the growth, a suctioning device may be used to help define the tumor, then an electrically charged wire is used to cut it out. The extracted tissue is removed through the endoscope and sent to a lab for analysis.

Recovering from an EMR

After the procedure, your care team will monitor your condition while the drowsiness subsides. Once you’re cleared to head home, you’ll get aftercare instructions, such as a diet to follow while your throat heals, as well as a list of symptoms to monitor. You’ll want to take it easy and rest when you get home.

If you underwent an EMR of your upper gastrointestinal tract (the endoscope was inserted into your esophagus), you will likely be advised to follow a liquid diet during the first one to two days of recovery. On the third day, you may be able to switch to more solid foods that are pureed or soft, such as smoothies, yogurt and applesauce.

Risks and complications

Shortly after an EMR, you may feel bloated, nauseous or gassy. There may be small amounts of blood in the esophagus or rectum (depending on where the growths were removed) that you may see when you cough or use the bathroom, respectively. An EMR of the upper gastrointestinal tract often causes a sore throat for a day or two.

More severe complications can also occur, including:

  • Narrowing of the esophagus (strictures), which may require medical intervention to resolve
  • Perforation or hole in the gastrointestinal tract, which may require surgery to treat
  • Persistent bleeding, which may stop on its own or require intervention
  • Complications from sedatives, such as depressed breathing, heart rate or blood pressure

Get medical attention right away if you experience:

  • Chest pain
  • Difficulty breathing
  • Worsening throat pain
  • Difficulty swallowing that gets worse
  • Vomit that is bloody or resembles coffee grounds
  • Bowel movements that are bloody, black or tar-colored
  • Fever

EMR results and benefits

The potential benefits of an EMR procedure vary depending on your individual circumstances. While limited, there is research that clearly demonstrates the benefits of EMRs on patient outcomes.

According to a study published in the journal Gut, of 405 people with early-stage stomach cancer confined to the mucosa, an EMR completely removed the tumors in 278 of the cases. All remained cancer-free during the 38 months they were followed by researchers. However, among the 127 patients whose tumors were incompletely removed, 17 experienced cancer recurrence and needed surgery.

Patient outcomes largely depend on the ability to extract all of the cancer using an EMR. Even small amounts of cancer that are left behind can continue to grow and spread. A study published in BMC Gastroenterology found that when an EMR is used for colon cancer, the recurrence rate is 12 percent to 16 percent.

Another factor that can influence outcomes is the experience of the doctor performing the procedure. EMRs aren’t common procedures in the United States. There may be varying levels of knowledge and experience across different hospitals and doctors, making it crucial to see a doctor who is specifically trained to perform EMRs.

For patients with cancers or precancers that are eligible for treatment with an EMR, one benefit is avoiding more invasive surgery. The alternative surgical options are, in many cases, more aggressive and may come with a higher risk of complications. Also, an EMR generally has a faster recovery time than traditional surgery, and it can lead to a better quality of life for some patients.

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