Colitis is inflammation of the inner lining of the colon and can be associated with diarrhea, abdominal pain, bloating, and blood in the stool. This inflammation may be due to a variety of reasons, including the following:
- loss of blood supply to the colon,
- inflammatory bowel disease, and
- invasion of the colon wall with lymphocytic white blood cells or collagen.
Anatomy of the colon
The colon, or large intestine, is a hollow, muscular tube that processes waste products of digestion from the small intestine, removes water and ultimately eliminates the remnants as feces (stool) through the anus. The colon is located within the abdominal cavity, the sac that contains the intestine.
The colon is surrounded by many layers of tissue. The innermost layer of the colon is the mucosa that comes into contact with the waste products of digestio is the mucosa absorbs water and electrolytes back into the blood vessels that are located just below the surface in the submucosa.
This is surrounded by a circular layer of muscles and then another outer layer of longitudinal muscles that run along the length of the colon. The muscles work together to help rhythmically squeeze liquid waste from the cecum through the entire length of the colon.
Water is gradually removed, turning the waste into formed stool, so that it is excreted out of the anus in solid form.
The colon frames the organs within the peritoneum and its segments are named based on their location.
The colon begins in the right lower quadrant of the abdomen, where the terminal ileum, the last part of the small intestine, attaches to the cecum, the first segment of the colon.
The appendix is attached to the cecum.
The ascending colon begins at the cecum and arises from the right lower abdomen to the right upper abdomen near the liver.
The colon then makes a sharp left turn called the hepatic flexure (hepatic=liver), and is referred to as the transverse colon, as it makes its way to the left upper quadrant of the abdomen near the spleen.
There is a sharp downward turn called the splenic flexure, and it is referred to as the descending colon as it runs from the left upper quadrant to the left lower quadrant of the abdomen.
When it descends into the pelvis, it is referred to as the sigmoid colon.
The last several centimeters of the colon are referred to as the rectum.
The anus is the final portion of the colon.
Hemorrhagic colitis can occur in people of all ages but is most common among children and older people. There are many strains of Escherichia coli (E. coli) that cause hemorrhagic colitis. In North America, the most common strain is E. coli O157:H7.
These bacteria naturally occur in the intestines of healthy cattle. Outbreaks can be caused by eating undercooked ground beef or by drinking unpasteurized milk or juice. Consuming food or water contaminated with cow manure or raw ground beef can also spread the infection.
The disease can be transmitted from person to person, particularly from children in diapers to other people. Inadequately chlorinated children’s wading pools can be a source of infection.
E. coli toxins damage the lining of the large intestine. If the bacteria enter the bloodstream, they can also affect other organs, such as the kidneys.
Severe abdominal cramps begin suddenly along with watery diarrhea, which may become bloody within 24 hours. The diarrhea usually lasts 1 to 8 days. Fever is usually absent or mild but occasionally can exceed 102° F (39° C).
About 5% of people with hemorrhagic colitis develop a severe complication called hemolytic-uremic syndrome (see Thrombotic thrombocytopenic purpura (TTP) and hemolytic-uremic syndrome (HUS)).
Symptoms include anemia (characterized by fatigue, weakness, and pale skin color) caused by the destruction of red blood cells (hemolytic anemia), a low platelet count (thrombocytopenia—see Thrombocytopenia (ITP, TTP)), and sudden kidney failure.
Some people with hemolytic-uremic syndrome also develop complications of nerve or brain damage, such as seizures or strokes. Hemolytic-uremic syndrome typically develops in the second week of illness, sometimes preceded by an increasing fever.
Hemolytic-uremic syndrome is more likely to occur in children under age 5 years and in people over age 60. Even without hemolytic-uremic syndrome and its complications, hemorrhagic colitis may cause death in older people.
- A doctor’s evaluation
- Stool tests
A doctor usually suspects hemorrhagic colitis when a person reports bloody diarrhea. To make the diagnosis, a doctor has stool specimens tested for strains of E. coli or the toxins they produce. Other tests, such as sigmoidoscopy, may be done if a doctor suspects that other diseases may be causing the bloody diarrhea.
Improved meat-processing procedures in the United States have helped reduce the rate of meat contamination with E. coli. Despite these measures, ground beef can still be contaminated. Thus, ground beef should be cooked to an internal temperature of 160° F (71° C) or until juices run clear.
Persons should drink only pasteurized milk and milk products. People should properly dispose of the stool of infected people, practice good hygiene, and wash their hands with soap to limit the spread of infection.
Children should no longer have diarrhea and should have two negative stool cultures before they are allowed to return to the child care center.
People should report outbreaks of bloody diarrhea to public health authorities, because intervention can prevent infection in other people.
Reporting can be done by contacting the local county Department of Health via information found on the web site or in the phone book.
- Drinking fluids
- Sometimes fluids by vein
The most important aspect of treatment is drinking enough fluids. Sometimes so much fluid is lost, however, that a doctor has to replace fluids by vein (intravenously).
Antibiotics are not given because they actually increase the risk of developing hemolytic-uremic syndrome.
People who develop complications are likely to require intensive care in the hospital and may need kidney dialysis (see Dialysis) and other specific treatment.