HomeHealth articlesmicroscopic colitisWhat Is Microscopic Colitis?

Microscopic colitis is an inflammatory bowel disease. To know more about the condition, read the following article.

Written by

Dr. Akanksha

Medically reviewed by

Dr. Ghulam Fareed

Published At December 16, 2022
Reviewed AtMay 2, 2023

What Is Microscopic Colitis?

Microscopic colitis is a chronic inflammatory bowel disease of the colon or large intestine, causing persistent watery, non-bloody diarrhea. Abnormal reactions of the immune system may cause this inflammation of the inner lining of the large intestine. This condition gets its name from the fact that it is important to examine the tissue of the large intestine under a microscope for its identification, as they appear normal when examined through other tests. The development of microscopic colitis is less common when compared to other inflammatory bowel diseases. The severity of microscopic colitis is not as severe as other inflammatory bowel diseases, and it is not considered a life-threatening disease. It can be controlled with medications as it tends to come and go.

What Are the Types of Microscopic Colitis?

The types of microscopic colitis are:

  1. Collagenous Colitis - In this type of microscopic colitis, a thick layer of protein (collagen) develops in the tissues of the colon. Collagen and elastin constitute the connective tissue of the intestinal lining. The thickened connective tissue is often seen in other conditions like rheumatoid arthritis, where collagen and elastin are inflamed. In patients with microscopic colitis, these autoimmune conditions are seen quite often.

  2. Lymphocytic Colitis - In this type of microscopic colitis, an increase in white blood cells (lymphocytes) is seen in the intestinal mucosa. An increased number of white blood cells accompanies inflammation with the involvement of the immune system. The function of white blood cells as a part of the immune system is to protect the body against any infection.

Both types of microscopic colitis show similar symptoms and have similar methods of treatment. The difference between both of them can be seen only under the microscope. It is believed by some that both types are the different stages of the same condition.

What Are the Sign and Symptoms of Microscopic Colitis?

The most important symptom of microscopic colitis is chronic watery diarrhea. Diarrhea occurs around five to six times a day, though some might have it more or less. The symptoms of this condition can come and go quite often, and at times they get resolved themselves. Other symptoms are:

  • Pain in the abdomen and cramps.

  • Bloating.

  • Loss of weight.

  • Dehydration.

  • Nausea.

  • Fatigue.

  • Accidental bowel leakage and nocturnal stools.

The symptoms might be present from months to two to three years before the diagnosis is made.

What Are the Causes of Microscopic Colitis?

The exact cause of microscopic colitis is not known clearly. According to the researchers, the possible causes can be

  • Medications - The medications like nonsteroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors, hormone replacement therapy, beta-blockers, selective serotonin reuptake inhibitors, and statins can irritate the lining of the large intestine.

  • Autoimmune Response - The individual’s body can react to a false threat and attack the healthy cells of his or her digestive system.

  • Bile Acid - When bile is not absorbed properly, it irritates the lining of the large intestine.

  • Bacteria and Viruses - An infection with bacteria or viruses may trigger inflammation and irritate the colon's lining by releasing toxins.

  • Genetics - Some researchers believe that genes could be one of the reasons for developing the disease.

How to Diagnose Microscopic Colitis?

A gastroenterologist is a specialist to be consulted for the diagnosis of microscopic colitis. The doctor would ask for medical history and any medication that the patient is taking, like Aspirin, proton pump inhibitors, Ibuprofen, Naproxen sodium, and selective serotonin reuptake inhibitors (SSRI) that can increase the risk of developing the disease. The doctor may go for the patient’s physical examination to rule out other conditions like celiac disease that may cause the symptoms. Other tests done for the diagnosis of microscopic colitis are:

  • Blood Tests - Blood tests are done to check for any infection and also to check for anemia.

  • Stool Tests: This test is done to rule out any other cause of diarrhea, like an infection.

  • Upper Endoscopy With Biopsy - This test is done to rule out celiac disease. A thin, flexible tube with an attached camera is used to examine the upper part of the gastrointestinal tract. A tissue sample can be collected for examining it in a laboratory.

  • Imaging Studies - Abdominal radiographs, computed tomography (CT) scans, and barium enemas show normal results and are non-specific in making a diagnosis.

  • Colonoscopy - This test helps in a thorough examination of the entire colon using a colonoscopy. A colonoscope is a flexible and long instrument that is inserted into the colon through the rectum after sedating the patient. A tissue sample can be taken from the intestinal lining by bypassing the tools through the colonoscope. This tissue sample will be examined under a microscope in a laboratory.

  • Flexible Sigmoidoscopy - This test is similar to a colonoscopy. Instead of viewing the entire colon, this test allows the doctor to view the inner lining of the rectum and most of the sigmoid colon - approximately the last two feet of the large intestine. This test involves the use of a sigmoidoscope, which is a flexible, slender, and lighted tube that helps to examine the inner lining of the intestine. Using this sigmoidoscope, a tissue sample can be collected for microscopic examination in a laboratory.

As the intestinal tissues usually appear normal in microscopic colitis, to make a clear-cut diagnosis of microscopic colitis, a tissue sample is required that is collected during the colonoscopy or flexible sigmoidoscopy. Under the microscope, cells of colon tissue in both types of microscopic colitis show distinct appearances leading to a definite diagnosis.

What Are the Treatment Options for Microscopic Colitis?

The treatment depends on the symptoms and how serious they are. The treatment plan includes lifestyle and dietary changes, over-the-counter medications, and prescription medications. At times, symptoms flare up and then go away on their own. Sometimes symptoms can be managed with dietary changes, and sometimes medicines are required to subside the symptoms.

1. Medications:

  • Antidiarrheals such as Diphenoxylate or Loperamide help in slowing down bowel contractions.

  • Bulking agents that make the stool more solid and slow its transit time, like Psyllium.

  • Steroids like Budesonide.

  • Anti-inflammatory medications that help in controlling colon inflammation, such as Mesalamine.

  • Bile acid sequestrants such as Colesevelam or Colestipol are given when the patient has bile acid malabsorption.

  • TNF (tumor necrosis factor) inhibitors help reduce inflammation by neutralizing an immune system protein, such as Infliximab or Adalimumab.

2. Surgery:

Surgery is indicated in cases where the symptoms are severe and medications are ineffective. The surgical process involves the removal of all or part of the colon or large intestine. Surgery is rarely needed in the treatment of microscopic.


Microscopic colitis is not a life-threatening condition. In most cases, it can be managed with lifestyle and dietary changes like drinking plenty of fluids, eating easy-to-digest food, and avoiding large meals at one time. Anybody can develop microscopic colitis, but it is more prevalent in females and older adults. It is also common in those who smoke and who have autoimmune diseases like celiac disease. The incidence of microscopic colitis is about 8 to 16 percent.

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Dr. Ghulam Fareed
Dr. Ghulam Fareed

Medical Gastroenterology

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