Microscopic Colitis

Microscopic colitis is a type of inflammation in your large intestine (colon) that causes chronic watery diarrhea. Unlike other forms of colitis, it cannot be seen during a standard colonoscopy. Instead, a doctor must examine tiny tissue samples (biopsies) under a microscope to find the inflammation, which gives the condition its name.

What is Microscopic Colitis?

Microscopic colitis is an inflammatory condition affecting the large intestine (colon) that leads to persistent watery diarrhea. It gets its name because the inflammation is only visible when a doctor examines a small tissue sample (biopsy) from the colon under a microscope, not during a regular visual inspection like a colonoscopy.

This condition is considered a type of inflammatory bowel disease (IBD), but it is different from Crohn's disease and ulcerative colitis, which are the more commonly known forms of IBD. The key difference is that with microscopic colitis, the lining of your colon appears normal to the naked eye during an endoscopy or colonoscopy. There are two main types of microscopic colitis: collagenous colitis and lymphocytic colitis. In collagenous colitis, a thick layer of a protein called collagen builds up under the lining of the colon. In lymphocytic colitis, there is an increased number of white blood cells called lymphocytes in the colon's lining. Both types cause similar symptoms and are treated in much the same way. Microscopic colitis is a chronic condition, meaning it can last a long time, but its symptoms often come and go. It is not considered a life-threatening condition and does not increase your risk of colon cancer.

Symptoms

The primary symptom of microscopic colitis is chronic, watery diarrhea that can occur many times a day, sometimes waking you up at night. Other common symptoms include abdominal pain or cramping, urgent bowel movements, and unintended weight loss due to the diarrhea.

Many people with microscopic colitis experience frequent, urgent bowel movements. This can significantly impact daily life and lead to dehydration if not managed properly. The diarrhea is typically watery and does not usually contain blood, which helps distinguish it from other types of colitis. Along with diarrhea, you might feel pain or cramping in your abdomen, which can range from mild to severe. Some individuals also report bloating, nausea, or a feeling of fullness. Because of the persistent diarrhea, some people may experience unintended weight loss, though this is less common than diarrhea and abdominal discomfort. Symptoms can vary in intensity and may come and go. Sometimes, symptoms might disappear for a period (remission) and then return (flare-up). It's important to discuss any persistent digestive symptoms with your doctor to get an accurate diagnosis.

Causes & risk factors

The exact cause of microscopic colitis is not fully understood, but it is thought to involve a combination of factors, including certain medications, autoimmune conditions, and possibly genetic predispositions. It is not caused by an infection or a specific food.

Several factors are believed to increase your risk of developing microscopic colitis. One significant risk factor is the use of certain medications. Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen, proton pump inhibitors (PPIs) used for acid reflux, and selective serotonin reuptake inhibitors (SSRIs) for depression have all been linked to the condition. Stopping these medications, if possible, can sometimes improve symptoms. Microscopic colitis is also more common in people with other autoimmune diseases, such as celiac disease, thyroid disease, rheumatoid arthritis, and type 1 diabetes. This suggests that an overactive immune system, which mistakenly attacks healthy tissues, may play a role in its development. Women are more likely to develop microscopic colitis than men, and it most often affects people over the age of 50. While the precise trigger remains unknown, researchers believe that an abnormal immune response in the colon, possibly initiated by certain drugs or infections, leads to the inflammation seen in microscopic colitis. Smoking is also considered a risk factor, as it can worsen inflammation in the digestive tract.

How it's diagnosed

Diagnosing microscopic colitis typically involves a colonoscopy with biopsies, as the colon appears normal during the visual examination. During the procedure, small tissue samples are taken from different parts of the colon and then examined under a microscope to identify the characteristic inflammation.

If you have chronic watery diarrhea, your doctor will likely start by taking a detailed medical history and performing a physical exam. They may also order stool tests to rule out infections or other causes of diarrhea. Blood tests might be done to check for signs of inflammation or other conditions. The definitive diagnosis of microscopic colitis requires a colonoscopy or flexible sigmoidoscopy. During these procedures, a thin, flexible tube with a camera is inserted into your rectum to view the inside of your colon. Even though the colon lining looks healthy to the naked eye, your doctor will take several small tissue samples (biopsies) from different areas. These biopsies are then sent to a pathologist, a doctor who specializes in examining tissues. The pathologist will look at the samples under a microscope to find the specific changes that confirm microscopic colitis, such as the thickened collagen layer or increased lymphocytes, depending on the type.

Treatment options

Treatment for microscopic colitis often begins with lifestyle changes and stopping any medications that might be contributing to the condition. If symptoms persist, anti-diarrheal medications, corticosteroids, or other anti-inflammatory drugs may be prescribed to reduce inflammation and control symptoms.

The first step in managing microscopic colitis is often to identify and stop any medications that could be causing or worsening your symptoms, such as NSAIDs or PPIs, under your doctor's guidance. Your doctor may also suggest dietary changes, such as avoiding caffeine, dairy, or gluten, though evidence for specific dietary triggers is limited and varies among individuals. For symptom relief, over-the-counter anti-diarrheal medications like loperamide can help reduce the frequency of bowel movements. If these are not enough, your doctor might prescribe budesonide, a type of corticosteroid that works mainly in the gut to reduce inflammation with fewer side effects than traditional steroids. It is often the first-line prescription treatment. If budesonide is not effective or if symptoms return after stopping it, other medications may be considered. These can include bile acid binders like cholestyramine, which help with diarrhea, or immunosuppressants such as azathioprine or methotrexate for more severe or resistant cases. In rare instances where medical treatments fail, surgery to remove part of the colon might be considered, but this is highly uncommon.

Recovery & outlook

Many people with microscopic colitis experience significant improvement in symptoms with treatment, and some may even achieve long-term remission. While symptoms can recur, the condition is generally manageable and does not lead to serious complications or increase the risk of colon cancer.

The outlook for people with microscopic colitis is generally good. Most individuals respond well to treatment, with many experiencing a reduction in diarrhea and other symptoms within a few weeks of starting medication. Some people may achieve complete remission, meaning their symptoms disappear entirely. However, microscopic colitis is often a chronic condition, and symptoms can return after treatment is stopped. This means some individuals may need long-term or intermittent treatment to manage their condition. Your doctor will work with you to find the most effective treatment plan to control your symptoms and improve your quality of life. It's important to continue regular follow-up appointments with your doctor to monitor your symptoms and adjust your treatment as needed. While microscopic colitis can be disruptive due to chronic diarrhea, it does not typically lead to severe complications like those seen in Crohn's disease or ulcerative colitis, and it does not increase your risk of developing colon cancer.

When to see a doctor

You should see a doctor if you experience persistent watery diarrhea, especially if it lasts for more than a few days, or if it is accompanied by severe abdominal pain, significant weight loss, or signs of dehydration. Early diagnosis can help manage symptoms and improve your quality of life.

It's important to seek medical attention for any chronic changes in your bowel habits. If you have watery diarrhea that continues for more than a week, or if it is frequent and severe, you should contact your healthcare provider. This is especially true if the diarrhea wakes you up at night. Also, be sure to see a doctor if your diarrhea is accompanied by other concerning symptoms. These include severe or worsening abdominal pain, unexplained weight loss, fever, or signs of dehydration such as extreme thirst, infrequent urination, or dizziness. These symptoms could indicate microscopic colitis or another underlying condition that requires medical evaluation. While microscopic colitis is not life-threatening, persistent diarrhea can lead to complications like dehydration and electrolyte imbalances. Getting a proper diagnosis allows your doctor to rule out other conditions and start appropriate treatment to relieve your symptoms and prevent further issues.

Frequently asked questions

Is microscopic colitis a serious condition?

Microscopic colitis is generally not considered a serious or life-threatening condition. While its symptoms, primarily chronic watery diarrhea, can be disruptive and significantly impact quality of life, it does not lead to severe complications like colon cancer or the need for extensive surgery in most cases.

Can microscopic colitis be cured?

While there isn't a definitive "cure" in the sense that it might never return, many people with microscopic colitis achieve long-term remission, meaning their symptoms disappear completely. Treatment often effectively controls symptoms, and some individuals may be able to stop medication without recurrence, though others may need ongoing management.

What foods should I avoid with microscopic colitis?

There is no specific diet universally recommended for microscopic colitis, and dietary triggers can vary among individuals. Some people find relief by avoiding caffeine, dairy products, or gluten. It's best to discuss dietary changes with your doctor or a dietitian, who can help you identify potential triggers and ensure you maintain adequate nutrition.

Is microscopic colitis hereditary?

The exact role of genetics in microscopic colitis is not fully understood. While it is not directly inherited like some other conditions, there may be a genetic predisposition, meaning some people might be more likely to develop it if they have a family history of autoimmune diseases. However, environmental factors and medications also play a significant role.

How long does a flare-up of microscopic colitis last?

The duration of a microscopic colitis flare-up can vary widely. Some people might experience symptoms for a few days or weeks, while others might have persistent symptoms for months if untreated. With appropriate treatment, symptoms often improve within a few weeks, but it's common for symptoms to come and go over time.

Can stress cause microscopic colitis?

Stress is not considered a direct cause of microscopic colitis. However, like many digestive conditions, stress can sometimes worsen existing symptoms or trigger a flare-up in individuals who already have the condition. Managing stress through relaxation techniques or other methods may help some people cope with their symptoms.

Sources

• MedlinePlus — Microscopic Colitis
• Mayo Clinic — Microscopic Colitis
• Cochrane Library — Microscopic Colitis