Crohn's Colitis

What is Crohn's colitis?

Crohn's colitis is a form of Crohn's disease, an inflammatory bowel disease (IBD), where the inflammation is located only in the colon (large intestine). Unlike ulcerative colitis, which affects only the innermost lining, the inflammation in Crohn's disease is transmural, meaning it can extend through the entire thickness of the bowel wall. This can lead to complications such as strictures (narrowing of the colon) and fistulas (abnormal tunnels from the colon to other organs or the skin).

Another key feature of Crohn's disease is that the inflammation can be patchy, with areas of diseased bowel separated by areas of healthy tissue. This is known as skip lesions. The disease can affect any part of the colon, from the cecum to the rectum.

What are the symptoms of Crohn's colitis?

The symptoms of Crohn's colitis are often similar to those of ulcerative colitis, but there can be some differences. Common symptoms include:

• Diarrhea: This may or may not be bloody. Bleeding is generally less common than in ulcerative colitis.
• Abdominal pain: Often cramping, which can be severe.
• Weight loss and poor appetite.
• Fever.
• Fatigue.
• Perianal disease: A significant number of patients with Crohn's colitis also have inflammation around the anus, which can manifest as skin tags, deep fissures, abscesses, and fistulas.

What causes Crohn's disease?

The exact cause of Crohn's disease is unknown, but it is believed to be a complex interplay of genetic, immune, and environmental factors.

• Genetics: Crohn's disease has a strong genetic component and often runs in families. Specific gene mutations (e.g., in the NOD2/CARD15 gene) have been linked to an increased risk.
• Immune System: The current leading theory is that in genetically predisposed individuals, the immune system launches an abnormally aggressive and ongoing attack against harmless bacteria in the gut, leading to chronic inflammation.
• Environmental Triggers: Factors like smoking, diet, and possibly previous infections may trigger the onset of the disease in someone who is genetically susceptible. Smoking is a well-established risk factor for developing Crohn's disease and for making the disease worse.

How is Crohn's colitis diagnosed?

Diagnosing Crohn's colitis involves a combination of tests to visualize the colon, look for complications, and rule out other conditions.

• Colonoscopy: This is the most important diagnostic test. A colonoscope is used to examine the entire colon and the end of the small intestine (terminal ileum). The doctor will look for the characteristic features of Crohn's, such as deep ulcers, a 'cobblestone' appearance of the lining, and skip lesions. Biopsies are taken to be examined for microscopic signs of inflammation, including granulomas, which are a hallmark of Crohn's disease.
• Imaging: A CT or MRI enterography is often used to get detailed pictures of the entire bowel, both the small intestine and the colon. This can help identify the extent of the disease, the presence of strictures, and complications like abscesses or fistulas.
• Blood and Stool Tests: Blood tests can show signs of inflammation (like an elevated CRP) and anemia. Stool tests are important to rule out infection as the cause of symptoms.

How is Crohn's colitis treated?

Treatment for Crohn's disease is aimed at reducing the inflammation, relieving symptoms, and preventing complications. There is no cure for Crohn's disease, but effective medical and surgical therapies can lead to long periods of remission.

Medications:

• Corticosteroids: Used for short-term control of moderate to severe flares.
• Aminosalicylates (5-ASA): These have a limited role in Crohn's disease but may be used for very mild colonic disease.
• Immunomodulators: Drugs like azathioprine or methotrexate are used to maintain remission and help patients get off of steroids.
• Biologic Therapies: These are powerful medications that target specific parts of the immune system. They are the mainstay of treatment for moderate to severe Crohn's colitis and its complications, like fistulas. Examples include anti-TNF agents, integrin receptor antagonists, and interleukin inhibitors.

Surgery:
Despite advances in medical therapy, a large proportion of patients with Crohn's colitis will require surgery at some point. Surgery is not a cure but is used to treat complications.

• Segmental Colectomy: If the disease is limited to a short segment of the colon, that piece can be removed and the ends reconnected.
• Subtotal or Total Colectomy: For more extensive disease, the entire colon (with or without the rectum) may need to be removed, which usually results in an ileostomy.
• Strictureplasty: A procedure to widen a narrowed segment of the colon without removing it.
• Abscess Drainage and Fistula Repair: For perianal disease.

Self-Care for Crohn's Disease

• Quit Smoking: This is the single most important lifestyle change a person with Crohn's can make. Smoking makes the disease more active and increases the need for medication and surgery.
• Diet: While no specific diet is proven to treat Crohn's, some people find that certain foods worsen their symptoms. Working with a dietitian can be helpful.
• Nutrition: Maintaining good nutrition is crucial, as the disease can affect nutrient absorption and appetite.

What's the difference between Crohn's colitis and ulcerative colitis?
While both are types of IBD affecting the colon, the main differences are the pattern and depth of inflammation. Ulcerative colitis involves continuous inflammation limited to the colon's inner lining. Crohn's colitis has patchy (skip lesions) inflammation that can go through the full thickness of the bowel wall, which is why it can cause complications like strictures and fistulas.

Will I need surgery for Crohn's colitis?
Many people with Crohn's colitis will need surgery at some point in their lives, often to treat a complication like a stricture, abscess, or fistula that is not responding to medication.

Does Crohn's colitis increase my risk of colon cancer?
Yes, similar to ulcerative colitis, long-standing and extensive inflammation of the colon from Crohn's disease increases the risk of developing colorectal cancer. Regular surveillance colonoscopies are recommended for patients who have had Crohn's colitis for 8 years or more.

• Smith RK, Holubar SD. Medical Therapy for Crohn's Disease. In: Steele SR, Hull TL, Hyman N, Maykel JA, Read TE, Whitlow CB, eds. The ASCRS Textbook of Colon and Rectal Surgery. 4th ed. Springer; 2022:781-795.
• National Institute of Diabetes and Digestive and Kidney Diseases. Crohn's Disease. Published September 2020. Accessed October 12, 2025. https://www.niddk.nih.gov/health-information/digestive-diseases/crohns-disease
• Crohn's & Colitis Foundation. What is Crohn's Disease? Accessed October 12, 2025. https://www.crohnscolitisfoundation.org/patientsandcaregivers/what-is-crohns-disease