What Is Microscopic Colitis?

Overview

Microscopic Colitis is a type of inflammatory bowel disease that affects the colon and causes chronic diarrhoea.¹ It is called "microscopic" because the inflammation can only be seen under a microscope. Treatment may include medication, changes in diet, and lifestyle modifications.² 

Understanding microscopic colitis is important for several reasons. First, it can help individuals recognise the signs and symptoms of the condition, allowing them to seek medical attention and receive a proper diagnosis. This can help prevent complications and improve outcomes. Second, understanding the causes of microscopic colitis can help individuals identify potential risk factors and make lifestyle changes to reduce their risk of developing the condition. Awareness of microscopic colitis can help reduce the stigma surrounding gastrointestinal disorders, which can improve the quality of life for individuals living with the condition.³

Understanding microscopic colitis is important for early detection, prevention, and improved management of the condition.

If you have concerns about this condition, keep reading to learn more about the signs and symptoms of microscopic colitis, the different types of this condition, the possible causes and risk factors, as well as the various treatment options available to manage the symptoms and improve the quality of life.

Causes of microscopic colitis

Despite ongoing research, the exact causes of microscopic colitis remain largely unknown. However, several factors have been identified that may contribute to the development of the condition.

Some possible causes include:^4,11,12

Abnormal immune system response

One of the leading theories regarding the development of microscopic colitis involves an abnormal immune system response. The immune system is responsible for defending the body against harmful substances like bacteria, viruses, and other pathogens. 

In individuals with microscopic colitis, there is evidence of an exaggerated immune response in the colon, resulting in inflammation and damage to the lining of the intestines. The specific triggers of this immune response are not fully understood, but it is believed to be a complex interplay of genetic susceptibility and environmental factors.

Genetics 

Genetics likely play a role in the development of microscopic colitis. Some studies have shown that individuals with a family history of inflammatory bowel diseases (IBD) or autoimmune disorders, such as Crohn's disease or ulcerative colitis, have a higher risk of developing microscopic colitis. This suggests that certain genetic factors may predispose individuals to the condition. 

However, no specific gene has been identified as the primary cause of microscopic colitis.

Environmental triggers

1. Medications

Some medications have been associated with an increased risk of developing microscopic colitis. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, and proton pump inhibitors (PPIs) used to treat acid reflux have been linked to the condition. However, not everyone who takes these medications will develop microscopic colitis, suggesting that other factors may be involved.

2. Infections

In some cases, gastrointestinal infections have been linked to the development of microscopic colitis. It is theorised that certain infections may trigger an immune response in the colon, leading to inflammation and the onset of the condition.

3. Stress

Although the exact relationship between stress and microscopic colitis is not fully understood, there is evidence to suggest that stress may exacerbate symptoms in some individuals. Stress can have a significant impact on the digestive system and may play a role in increasing inflammation in the colon.

Hormonal factors 

Hormonal factors may also play a role in the development of microscopic colitis, particularly in women. Some studies have shown that the condition is more common in women and that it may be associated with hormonal changes, such as those experiencing menopause. However, more research is needed to fully understand the extent of hormonal influences on microscopic colitis.

It is important to recognize that while these factors are associated with microscopic colitis, they are not the sole causes. The condition is likely multifactorial, involving a combination of genetic susceptibility, abnormal immune responses, and environmental triggers. 

Due to the complexity of the disease, it is crucial to consult a medical professional for a proper evaluation, diagnosis, and personalised treatment plan based on the individual's unique case and symptoms.

Types of microscopic colitis

There are two major types:⁵

Collagenous colitis

Collagenous colitis is characterised by a thick band of collagen in the lining of the colon, which can cause inflammation and diarrhoea. 

Lymphocytic colitis

Lymphocytic colitis is characterised by an increase in white blood cells (lymphocytes) in the lining of the colon, which can also lead to inflammation and diarrhoea. 

Both types of microscopic colitis have similar symptoms and are treated in similar ways, but they can be distinguished by the presence or absence of the collagen band in the colon lining.

Signs and symptoms of microscopic colitis

Here are the signs and symptoms of microscopic colitis:^6,13

Chronic diarrhea 

Individuals with microscopic colitis may exhibit a variety of signs and symptoms, but chronic diarrhoea is the most common symptom.

Other Symptoms

Other symptoms may include 

• Abdominal pain or cramping 
• Weight loss 
• Fatigue
• Dehydration

Some people with microscopic colitis may also experience 

• Nausea
• Vomiting
• Fever

Since these symptoms are similar to other digestive conditions, it is important to seek medical attention to properly diagnose microscopic colitis and begin treatment to manage symptoms.

Diagnosis of microscopic colitis

Microscopic Colitis can be diagnosed by:^7,14

Physical exam & medical history review

The diagnostic process begins with a thorough physical examination by a healthcare professional. During this examination, the doctor will inquire about the patient's symptoms, medical history, and any relevant risk factors. They will also ask about the duration and frequency of diarrhoea, abdominal pain, and other associated symptoms. 

Gathering a comprehensive medical history helps the doctor identify potential triggers, underlying conditions, and any family history of gastrointestinal disorders or autoimmune diseases.

Stool tests

Stool tests are essential to rule out infectious causes of diarrhoea, as these conditions can have similar symptoms to microscopic colitis. The doctor may order stool tests to check for the presence of bacteria, parasites, or other pathogens that could be causing the symptoms. 

If the tests come back negative for infectious agents, it suggests that the diarrhoea is likely not due to an infection, and the physician can proceed with further evaluation for other potential causes.

Colonoscopy with biopsy

Colonoscopy with biopsy is considered the gold standard for diagnosing microscopic colitis. During this procedure, a thin, flexible tube with a camera at its tip (colonoscope) is inserted through the rectum and advanced through the entire colon. This allows the doctor to visually inspect the colon lining for any abnormalities, inflammation, or other signs of microscopic colitis.

During the colonoscopy, the doctor may observe subtle changes in the colon's mucosal appearance, which can be indicative of microscopic colitis. However, visual inspection alone is not sufficient for a definitive diagnosis. Therefore, multiple biopsies are taken from various parts of the colon during the procedure. Biopsies involve removing small tissue samples from the colon's lining using specialised instruments passed through the colonoscope.

Examination of tissue samples

The tissue samples collected during the colonoscopy are sent to a pathology laboratory, where they are processed and analysed by a pathologist. 

The pathologist examines the tissue samples under a microscope to look for specific microscopic changes that are characteristic of microscopic colitis. The two main subtypes of microscopic colitis are collagenous colitis and lymphocytic colitis, each having distinct microscopic features that can be identified during the examination.

In collagenous colitis, a characteristic finding is a thickened layer of collagen in the subepithelial tissue, which is the tissue layer beneath the surface lining of the colon. 

In lymphocytic colitis, an increased number of lymphocytes (a type of white blood cell) is observed in the colon lining. These microscopic features help differentiate microscopic colitis from other inflammatory bowel conditions.

By combining the information obtained from the physical exam, medical history review, stool tests, colonoscopy, and biopsy results, the healthcare provider can make a definitive diagnosis of microscopic colitis and develop an appropriate treatment plan for the patient. 

Management and treatment for microscopic colitis

The management and treatment of microscopic colitis depend on the severity of the symptoms and the type of the condition^8,15 

Medicines

Treatment may include: 

• Anti-diarrheal drugs
• Corticosteroids 
• Immunosuppressants

Dietary changes

Dietary changes such as avoiding trigger foods and maintaining low-fat, low-fibre diet may also help manage symptoms. 

Lifestyle modifications

Lifestyle modifications such as reducing stress, quitting smoking, and avoiding alcohol may also be helpful. In severe cases, surgery may be necessary. 

Surgery (in severe cases)

Surgery for microscopic colitis is rare and typically only recommended in severe cases where other treatments have not been effective. The surgical procedure may involve the removal of partial or all of the colon.

FAQs

How common is microscopic colitis?

Microscopic colitis is a relatively rare condition, affecting less than 1% of the population. The incidence of microscopic colitis is believed to be increasing. It is more common in middle-aged women and may be associated with certain medications or autoimmune disorders. If you are experiencing symptoms of chronic diarrhoea or abdominal pain, it is important to seek medical attention for proper diagnosis and treatment.

How is microscopic colitis diagnosed?

 Diagnosis of microscopic colitis typically involves a physical exam, review of medical history, stool tests, and colonoscopy with biopsy. During a colonoscopy, a small tissue sample is removed from the colon and examined under a microscope to look for signs of inflammation.

How can I prevent microscopic colitis?

There is no known way to prevent microscopic colitis, but making healthy lifestyle choices such as avoiding smoking, reducing stress, and maintaining a healthy diet may help reduce the risk of developing the condition.

What are the types of microscopic colitis?

Microscopic colitis has two distinct types- collagenous colitis and lymphocytic colitis. Collagenous colitis is distinguished by a thickened layer of collagen in the colon, whereas lymphocytic colitis is characterised by an elevated number of immune cells in the lining of the colon.

Who is at risk of microscopic colitis?

While microscopic colitis can impact anyone, it frequently affects middle-aged women. Risk factors that may increase the likelihood of developing this condition include a family history of the disease, autoimmune disorders, and the use of certain medications like nonsteroidal anti-inflammatory drugs (NSAIDs).

How common is microscopic colitis?

Microscopic colitis is a relatively rare condition, affecting less than 1% of the population. However, the incidence of microscopic colitis is believed to be increasing.

When should I see a doctor?

If you are experiencing chronic diarrhoea or other symptoms such as abdominal pain, cramping, or fatigue, you should see a doctor for proper evaluation and diagnosis. Prompt diagnosis and treatment can help manage symptoms and improve quality of life.

Summary

Microscopic colitis is categorised as an inflammatory bowel disease that affects the colon and leads to chronic diarrhoea. The exact cause of this condition is uncertain, but some factors, such as genetics, environmental triggers, and abnormal immune system response, may play a role. Two distinct types of microscopic colitis exist, one is collagenous colitis and the other is known as lymphocytic colitis. Diagnosis involves a physical examination, review of medical history, stool tests, and colonoscopy with biopsy. To manage symptoms and improve quality of life, treatment options include medication, dietary adjustments, and lifestyle changes. Although there is no certain way to prevent microscopic colitis, making healthy lifestyle choices can help minimize the risk of developing this condition. Prompt diagnosis and treatment can significantly help in managing symptoms.