Microscopic colitis is a condition that often causes chronic diarrhea, yet it can be difficult to identify during routine examinations. This is because the inflammation it causes in the colon is not visible to the naked eye during a standard endoscopy. Instead, specialized diagnostic steps are necessary to pinpoint this often-overlooked cause of persistent digestive issues.
What is Microscopic Colitis?
Microscopic colitis is an inflammatory condition affecting the colon, where the inflammation is only detectable through microscopic examination of tissue samples. Unlike other inflammatory bowel diseases like Crohn’s disease or ulcerative colitis, the colon appears normal during a standard colonoscopy. This characteristic is why it is termed “microscopic”.
There are two primary subtypes of microscopic colitis: collagenous colitis and lymphocytic colitis. Collagenous colitis is marked by a thickened layer of collagen, a structural protein, beneath the lining of the colon. Lymphocytic colitis, on the other hand, shows an increased number of lymphocytes, a type of white blood cell, within the colon’s lining. Despite these distinct microscopic features, both subtypes generally present with similar symptoms and respond to similar treatment approaches.
Common Symptoms to Look For
The most common symptom is chronic, watery, non-bloody diarrhea. This can be severe, with individuals experiencing multiple bowel movements daily, sometimes waking them from sleep.
Other symptoms often accompany microscopic colitis, including abdominal pain or cramping, bloating, and an urgent need to have a bowel movement. Some individuals may also experience fecal incontinence. Unintended weight loss and fatigue can occur, especially with severe and prolonged diarrhea.
How Doctors Rule Out Microscopic Colitis
Doctors begin ruling out microscopic colitis by considering a patient’s symptoms, especially chronic watery diarrhea. They typically conduct initial tests to exclude other common causes of chronic diarrhea, such as infections, celiac disease, or other inflammatory bowel diseases. This may involve stool sample analysis to check for infections or blood tests to screen for conditions like celiac disease.
The definitive diagnosis requires a colonoscopy with biopsies of the colon lining. Even if the colon appears normal visually, small tissue samples are taken from different sections. A pathologist then examines these biopsies under a microscope, looking for characteristic inflammatory changes of either collagenous or lymphocytic colitis. Without these microscopic examinations, microscopic colitis cannot be confirmed or excluded.
Treatment Options for Microscopic Colitis
Managing microscopic colitis often involves a stepwise approach, starting with less invasive methods. Lifestyle modifications, such as avoiding caffeine, artificial sweeteners, or alcohol, may help alleviate symptoms. If co-occurring conditions like lactose intolerance or celiac disease are present, adhering to appropriate dietary restrictions is also important.
Medications are frequently used to manage microscopic colitis symptoms. Over-the-counter anti-diarrheal agents, such as loperamide or bismuth subsalicylate, can provide symptomatic relief. For more persistent symptoms, a corticosteroid like budesonide is often considered a first-line therapy due to its effectiveness in reducing colon inflammation. In cases where budesonide is ineffective or symptoms are severe, other medications such as bile acid sequestrants like cholestyramine, or even immunomodulators like azathioprine, may be prescribed.