Diverticulitis is a condition in which diverticuli in the colon rupture. The rupture results in infection in the tissues that surround the colon.The colon (large intestine) is a long tube-like structure that stores and then eliminates waste material. Pressure within the colon causes bulging pockets of tissue (sacs) that push out from the colonic walls as a person ages. A small bulging sac pushing outward from the colon wall is called a diverticulum. More than one bulging sac is referred to as diverticula. Diverticula can occur throughout the colon but are most common near the end of the left colon called the sigmoid colon. The condition of having these diverticula in the colon is called diverticulosis.

A patient with diverticulosis may have few or no symptoms. When a diverticulum ruptures and becomes infected, the condition is called diverticulitis. A patient suffering from diverticulitis will have abdominal pain, abdominal tenderness, and fever. When bleeding originates from a diverticulum, it is called diverticular bleeding. A patient who suffers the consequences of diverticulosis in the colon is referred to as having diverticular disease.

Whereas most patients with diverticular disease have no or few symptoms, some patients will develop bleeding, rupture and infection (diverticulitis), constipation, abdominal cramps, and even colonic obstruction.

How do diverticula form?
The muscular wall of the colon grows thicker with age. Thickening of the colon wall may reflect the increasing pressures required by the colon to eliminate feces. A diet low in fiber can lead to small, hard stools which are difficult to pass. Over time, vigorous contractions in the colon push the inner intestinal lining outwards (herniates) through cracks in the muscle walls. These pouches or sacs that develop are called diverticula.

What are the symptoms of diverticular disease?
Most patients with diverticulosis have few or no symptoms. The diverticulosis condition in these individuals is found incidentally during tests for other intestinal problems. Twenty percent of patients with diverticulosis will develop symptoms related to diverticulosis. The most common symptoms of diverticular disease include abdominal cramping, constipation, and diarrhea.These symptoms are related to difficulty of passing stool along the left colon narrowed by diverticular disease. More serious complications include diverticulitis, collection of pus (abscess) in the pelvis, colon obstruction, generalized infection of the abdominal cavity (bacterial peritonitis), and bleeding into the colon.

A diverticulum can rupture, and the bacteria within the colon can spread into the tissues surrounding the colon causing diverticulitis. Constipation or diarrhea may also occur. A collection of pus can develop around the inflamed diverticulum, leading to formation of an abscess, usually in the pelvis. On rare occasions, the inflamed diverticula can erode into the urinary bladder, causing bladder infection and passing of gas during urination. Inflammation in the colon can also lead to bowel obstruction. Infrequently, a diverticulum ruptures freely into the abdominal cavity causing a life threatening infection called peritonitis.

Diverticular bleeding occurs when the expanding diverticulum erodes into a blood vessel at the base of a diverticulum. Rectal passage of red, dark or maroon-colored blood and clots occur without any associated abdominal pain. Rarely, blood may be black from a diverticulum of the right colon. Bleeding may be continuous or intermittent, lasting several days.

Patients with active bleeding usually are hospitalized for monitoring. Intravenous fluids are given to support the blood pressure. Blood transfusions are necessary for those with moderate to severe blood loss. In a rare individual with brisk and severe bleeding, the blood pressure can drop, causing dizziness, shock, and loss of consciousness. In most patients, bleeding stops spontaneously and they are sent home after several days in the hospital. Patients with persistent, severe bleeding require surgical removal of the bleeding diverticula.