Pseudomembranous colitis is an inflammatory process that occurs when your colon lining is being injured. Plaques called “pseudomembranes” develop at the site of the injury.
Pseudomembranous colitis (PMC) is a severe form of colitis. In this condition, something attacks and injures your colon lining (mucosa). It might be bacteria, toxins or another illness. Your colon mucosa develops thickened, scab-like plaques over the wounds. Your healthcare provider might call these “pseudomembranes.”
Pseudomembranes develop on mucous membranes, like your colon lining, when cells die. Your immune system sends white blood cells to the site of the injury. Leftover cellular debris combines with white blood cells called neutrophils to form pseudomembranes. They’re raised areas on the mucosa, up to 2 centimeters (cm) wide, with a yellow-white color.
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Pseudomembranous colitis symptoms include:
You might notice some bleeding or pus in your poop, but not always.
C. diff (Clostridioides difficile) infection is the most common cause of pseudomembranous colitis. C. diff is a bacterial infection that produces toxins that injure your colon lining. About 10% of C. diff infections progress to pseudomembranous colitis. This produces more than 90% of all cases. But other causes of colitis can also cause similar damage.
C. difficile produces toxins that injure your colon mucosa, causing cell death. C. diff infection also can become unusually severe, unusually fast. C. diff infection usually happens after you’ve taken antibiotics. Antibiotics reduce the other bacteria in your gut, but they don’t affect C. diff. This allows C. diff to quickly grow out of control.
Any antibiotic that kills the other helpful bacteria in your gut, but not C. diff, can make you vulnerable to a C. diff infection and pseudomembranous colitis. But some are considered higher risk. They include:
Other causes of colitis can also lead to pseudomembranous colitis, including:
In these cases, colitis is more severe or more complicated than usual. Complications can include reduced blood flow to your colon mucosa (ischemia), which can lead to tissue death and pseudomembranes. Preexisting conditions like inflammatory bowel disease (IBD) may also make your colon more vulnerable.
You’re more likely to develop pseudomembranous colitis if you:
When colitis becomes severe and difficult to control, as pseudomembranous colitis can be, it can lead to additional complications, some of which are life-threatening. Complications can include:
A healthcare provider will listen to your symptoms and ask you questions about your health history. They might order various tests to look for the cause of your symptoms, including blood tests, imaging tests and poop tests. They’ll look for signs of infection or inflammation and other red flags.
They’ll test your poop for evidence of C. diff infection. If they find it, they’ll start your treatment for it right away. They might not have any reason to look inside your colon for evidence of pseudomembranes unless you have complications or you aren’t responding to the treatment.
Sometimes, signs of pseudomembranous colitis show up on an imaging test (radiology). Your provider might see a pattern in the images that suggests severe colitis or damage to the mucosa, such as the “thumbprint sign” or the “accordion sign.” This might prompt further investigation.
To investigate further, the next step would be to look inside your colon for the cause of your symptoms. The exam to look inside your colon is called a colonoscopy. If your provider finds pseudomembranes during a colonoscopy, they’ll take a tissue sample (biopsy) and send it to a lab to confirm it.
The treatment depends on the cause. You may need specific antibiotics for a bacterial infection, like C. diff, or you may need to discontinue medications that are causing or contributing to your colitis. In some cases, healthcare providers may prescribe medications to reduce inflammation in your colon.
Some people only need supportive care, like IV fluids for dehydration or IV nutrition so their colon can rest. Others may need treatment for complications or even intensive care. Some people with very severe colitis or with complications may need surgery to remove part of their colon (colectomy).
If C. diff infection is the cause of your pseudomembranous colitis, there are a few drugs that can treat it. Your provider will choose the best one for you. Drugs to treat C. diff infection include:
The most important way to prevent pseudomembranous colitis is to prevent the spread of C. diff in vulnerable communities, like hospitals and nursing homes. People in these communities are more likely to become infected and to develop more severe symptoms like pseudomembranous colitis.
Healthcare providers in these settings take special precautions to control C. diff infection:
Yes, treatment can relieve pseudomembranous colitis. Most of the time, symptoms resolve quickly, but some people need more treatment than others. A persistent case of C. diff infection that keeps coming back may need a minor procedure to cure. Some complicated cases may require surgery.
Only 2% of pseudomembranous colitis cases are fatal. The rate is closer to 15% among people in long-term care facilities, who are already immunocompromised. Toxic megacolon has a 35% fatality rate.
Seek immediate care if you have:
A note from Cleveland Clinic
Bacterial infections that cause colitis are common, and most of the time, they aren’t serious. Not everyone who gets a C. diff infection will develop pseudomembranous colitis. But it can be scary if you do. You may be alarmed to learn that your colon is being injured on the inside. You may have upsetting symptoms, like pain and bleeding.
If you develop these symptoms, you need special care. But with care, your colon can heal. Mucous membranes like your colon lining heal well, once the injury has stopped. If your colitis symptoms don’t seem to be going away, talk to a healthcare provider. They’ll work to find and stop what’s causing your colitis and give your colon the rest it needs.
Last reviewed by a Cleveland Clinic medical professional on 08/29/2023.
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