What Is Colitis?

What is Colitis?
What is colitis? is one of the most frequently asked questions regarding colitis.

Colitis refers to the inflammation or swelling of the colon or large intestine. Click here for a brief tour of the colon.

There are many different types of colitis including:

  • Ulcerative colitis: this type of colitis is characterized by the presence of ulcers on the lining of the large intestine or colon. It usually affects the lower part of the colon or rectum. There is no scientific consensus as to the cause of this type of colitis.

  • Microscopic colitis: this type of colitis can only be identified by means of a microscope, hence its name. In cases of microscopic colitis the large intestine seems normal in appearance to the naked eye with no overt signs of inflammation (swelling, bleeding, redness). Colonoscopy results are thus either normal or near-normal. In such circumstances, a microscopic examination of a small sample of tissue from the colon reveals inflammation. Microscopic colitis is the collective name for two types of colitis: lymphocytic colitis and collagenous colitis. Indeed some experts believe that these forms of colitis are phases of the same disease as opposed to separate conditions. Both are characterized by an increase in number of white blood cells known as lymphocytes. Additionally in collagenous colitis there is a thickening in the amount of collagen beneath the lining of the colon.

  • Infectious colitis: viruses, bacteria and parasites can all result in inflammation of the colon or colitis. Some of the most common bacterial causes of colitis include Shingella, Campylobacter and Escherichia coli (also known as E. coli).

    The parasite Giardia is also capable of causing infectious colitis, as is the viral infection Cytomegalovirus. Infectious colitis can also occur as complication of antibiotic therapy, which causes an overgrowth of the bacterium Clostridium difficile (also known as C. Diff). This type of colitis is known as Pseudomembranous colitis (PMC), antibiotic-associated colitis, Clostridium difficile colitis or simply C. difficile colitis) is an acute condition which can be life-threatening. It occurs most commonly in patients who are already or have been in hospital, where the infection spreads from patient to patient.

  • Ischemic colitis: (also spelled Ischaemic colitis): Literally meaning restricted (isch) blood supply (emia), inflammation in this type of colitis is caused by a temporary loss of or reduction in blood flow to the colon. Ischemic colitis occurs mainly in adults over the age of fifty as well as in people with additional health problems including diabetes and heart disease.

  • Iatrogenic colitis is an adverse condition caused by medical treatment. It includes two subtypes: Chemical colitis, which is caused by the wrong or repeated administration of chemical treatments and Diversion colitis, which can result following bowel diversion surgery such as ileostomy and colostomy.

  • Necrotizing Enterocolitis: primarily affects premature infants and is caused by the death of intestinal tissue. In severe cases this causes a hole (perforation) in the intestine, which allows bacteria to leak into the abdomen resulting in life-threatening infection.
Some types of colitis are acute (self-limiting) whilst others are chronic (persistent).

Colitis can affect the entire colon or parts of the colon. In general, the greater the area of inflammation, the more severe the symptoms.

The prevalence of colitis also varies according to type. Some forms of colitis are more troublesome than others.

Symptoms of Colitis

The signs and symptoms of colitis can include:

  • Abdominal pain

  • Diarrhea

  • Blood in stools

  • Fatigue

  • Cramping

  • Urgency to empty bowel

  • Loss of appetite

  • Bloating

These symptoms will differ according to the etiology of the given colitis.

Diagnosis of Colitis

Colitis is usually diagnosed based upon medical history as well as the results of laboratory tests and medical procedures. The most accurate procedures for diagnosing colitis are by means of a visual examination (using a flexible tube connected to a camera) of the entire colon (colonoscopy) or the sigmoid (final part of the colon) (sigmoidoscopy). Barium enemas are also sometimes used to assist in the diagnosis of colitis.

Treatment of Colitis

Treatment for colitis depends on the cause. Colitis, which is caused by bacterial infection is often treated with antibiotics. Ulcerative colitis is treated with anti-inflammatory and immune suppressant medications, whereas the treatment for ischemic colitis focuses on hydrating the bowel.


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