Inflammatory Bowel Disease: Is It Ulcerative Colitis or Crohn's?

An estimated 3 million Americans live with inflammatory bowel disease (IBD), and as many as 70,000 people are newly diagnosed in the United States each year.  Crohn’s disease and ulcerative colitis are the most common types of IBD — both conditions cause chronic inflammation in the gastrointestinal (GI) tract. What sets these two conditions apart?

Differences Between Ulcerative Colitis and Crohn’s Disease

The primary difference between Crohn’s and ulcerative colitis (UC) is where the inflammation is located within the digestive system.

Ulcerative colitis affects the large intestine (colon). Chronic inflammation from ulcerative colitis can lead to ulcers forming on the large intestine. Ulcerative colitis appears in a continuous pattern and affects the innermost lining of the GI tract.

Crohn’s disease can affect all areas of the digestive tract and may be found anywhere from the mouth to the rectum, though it most commonly affects the end of the small intestine, the ileum. Crohn’s disease may appear in “patches” throughout the intestine, affecting some areas of the GI tract while others remain unaffected. Onset is usually gradual with subtle symptoms, depending on the part of the GI tract that is affected.

Shared Signs and Symptoms

Ulcerative colitis and Crohn’s disease share many similar symptoms. If you have UC, you may experience symptoms such as:

• Abdominal pain (most typically on the left side)

• Blood in the stool

• Chronic diarrhea

• Fatigue

• Fever

• Malaise

• Mucus in the stool

• Urgent need to move bowels

• Weight loss

If you have Crohn’s disease, you may experience symptoms such as:

• Abdominal pain

• Anemia

• Blood in the stool

• Chronic diarrhea

• Fever

• Mouth sores

• Pain and/or drainage around the anus

• Weight loss

Both conditions can lead to symptoms outside of the GI tract, including joint pain, mouth ulcers, skin rash, kidney stones and eye inflammation that may cause red eyes, blurry vision or eye pain.

About 10 percent of those with IBD exhibit symptoms of both Crohn’s disease and ulcerative colitis, and a definitive diagnosis can be difficult. This is typically referred to as “indeterminate colitis.”

How Will My Doctor Make Diagnosis?

Researchers aren’t sure what causes Crohn’s and ulcerative colitis, but both may be linked to genetics, environmental factors and your microbiome. Patients who have autoimmune conditions, such as arthritis, are more likely to develop IBD.

If you suspect you may have ulcerative colitis or Crohn’s disease, talk to your doctor, who will do a physical examination and ask about your symptoms. They may run blood and stool tests, do a biopsy or use imaging tests to give a diagnosis. You may be referred to a gastroenterologist.

Ulcerative colitis is often diagnosed by colonoscopy, a procedure in which the doctor will use an endoscope — a flexible tube with a camera — to see and take pictures of your GI tract lining. With UC, your doctor will be able to see any ulcers and inflammation along the lining of your intestinal tract.

The same tests are often used to test for Crohn’s disease. Your doctor may also run a small bowel evaluation using CT enterography or MR enterography (a diagnostic procedure that uses contrast to obtain clear pictures of your small bowel) to identify any abnormalities in the intestinal tract.

Both conditions can be managed with proper treatment. You may experience recurring episodes — known as “flares'' — that come and go. It’s important to take your medications as prescribed, eat a balanced diet and speak with your doctor about any additional or worsening symptoms you may experience.