The Difference Between Crohn’s, UC, and IBD

Written by Michael Kerr and Kristeen Cherney | Published on June 30, 2015
Medically Reviewed by George Krucik, MD on June 30, 2015

Overview

Many people are confused when it comes to the differences between inflammatory bowel disease (IBD), Crohn's disease, and ulcerative colitis (UC). The short explanation is that IBD is the umbrella term for the condition under which both Crohn's disease and ulcerative colitis fall. But there is, of course, much more to the story.

Both Crohn’s and UC are marked by an abnormal response by the body’s immune system, and they may share some symptoms. However, there are important differences as well. These distinctions primarily include the location of the maladies in the gastrointestinal (GI) tract and the way each disease responds to treatment. Understanding these features is key to obtaining a proper diagnosis from a gastroenterologist.

Inflammatory Bowel Disease

IBD was seldom seen before the rise of improved hygiene and urbanization at the beginning of the 20th century. Today, it’s still found mainly in developed countries such as the United States. Like other autoimmune and allergic disorders, it’s believed that a lack of germ resistance development has partly contributed to diseases such as IBD.

In people with IBD, the immune system mistakes food, bacteria, or other materials in the GI tract for foreign substances and responds by sending white blood cells into the lining of the bowels. The result of the immune system's attack is chronic inflammation. The word inflammation itself comes from the Greek word for flame. It literally means "to be set on fire."

Crohn’s and UC are the most common forms of IBD. Oftentimes, the terms are interchangeable. Less common IBDs include:

  • microscopic colitis
  • diverticulosis-associated colitis
  • collagenous colitis
  • lymphocytic colitis
  • Behçet's disease.

IBD may strike at any age. According to the Mayo Clinic, most people with IBD are diagnosed before the age of 30. It’s more common:

  • in urban areas
  • among people in higher socioeconomic brackets
  • industrialized countries
  • northern climates
  • in Caucasians as opposed to darker-skinned people and those of Asian descent
  • in people who eat high-fat diets

Aside from environmental factors, genetic factors are believed to play a strong role in the development of IBD. Therefore, it’s considered to be a "complex disorder.”

Unfortunately, there’s currently no cure for IBD. This is a lifelong disease, with alternating periods of remission and flare-up. Modern treatments, however, allow people to live relatively normal and productive lives.

IBD should not be confused with irritable bowel syndrome (IBS). IBS is a much less serious affliction than either Crohn’s disease or ulcerative colitis. It doesn’t involve inflammation or appear to have a physiological basis.

Crohn’s Disease

Crohn’s disease may affect any part of the GI tract from the mouth to the anus, although it’s most often found at the end of the small intestine (small bowel) and the beginning of the colon (large bowel).

Symptoms of Crohn's disease include:

  • persistent diarrhea
  • crampy abdominal pain
  • fever
  • occasional rectal bleeding
  • fatigue

Unlike with UC, Crohn's isn't limited to the GI tract. It may also affect the skin, eyes, joints, and liver. Since symptoms usually get worse after a meal, patients with Crohn's will often experience weight loss due to food avoidance.

Crohn's disease can cause blockages of the intestine due to scarring and swelling. Ulcers (sores) in the intestinal tract may develop into tracts of their own, known as fistulas. Crohn’s disease can also increase the risk for colon cancer, which is why patients must have regular colonoscopies.

Medication is the most common way to treat Crohn's disease. The five types of drugs are:

  • steroids
  • antibiotics
  • immune modifiers, such as azathioprine and 6-MP
  • aminosalicylates, such as 5-ASA
  • biologic therapy

Some cases may also require surgery. Still, surgery will not cure Crohn’s disease.

Ulcerative Colitis

Unlike Crohn's, UC is confined to the colon (large bowel) and only affects the top layers in an even distribution. Symptoms of UC include:

  • crampy abdominal pain
  • loose stools
  • bloody stool
  • urgent bowel
  • fatigue
  • loss of appetite
  • anemia due to blood loss (in severe cases only)

The symptoms of UC can also vary by type. According to the Mayo Clinic, there are five kinds of UC:

  • acute severe UC (a rare form that causes eating difficulties)
  • left-sided colitis (affects descending colon and rectum)
  • pancolitis (affects the whole colon and causes persistent bloody diarrhea)
  • proctosigmoiditis (affects lower colon and rectum)
  • ulcerative proctitis (mildest form that affects the rectum only)

With the exception of biologic therapy, treatments for the disease are the same as for Crohn's. Unlike with Crohn's, however, most patients with UC will almost never require surgery. 

Children with the disease may not develop or grow properly. Remission periods tend to be longer with UC than with Crohn's disease, and complications are far less frequent. Still, when complications do occur, they can be severe. Left untreated, UC may lead to:

  • holes in the colon
  • colon cancer
  • liver disease
  • osteoporosis
  • blood clots

Diagnosing IBD

There’s no doubt that IBD can significantly decrease quality of life, between uncomfortable symptoms and frequent bathroom visits. Even worse is the fact that IBD can lead to scar tissue, and even permanent damage. If you experience any unusual symptoms, it’s important to call a doctor. You may be referred to a gastroenterologist for IBD testing, such as a colonoscopy or a CT scan. Diagnosing the right form of IBD will lead to more effective therapies.

While there’s no cure for any form of IBD, early treatment and lifestyle changes can help minimize damage and complications. Treatment will also reduce the amount of symptoms.

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