Diverticular disease of the colon is a condition where small outpouchings of the colon wall occur. These outpouchings are called "diverticuli". The most commonly accepted understanding of how diverticuli occur is that a diet low in fiber and high in red meat causes the muscular colon to squeeze at greater pressures to cause it to move along its course. As the pressure inside the colon increases points of weakness occur along the walls of the colon and these areas bulge out over time to create diverticuli. This most commonly occurs in the sigmoid colon which is the last part of the colon before it empties into the rectum. When many diverticuli are present in the colon wall, this is called "diverticulosis". Diverticulosis is very common and increases with age.
The majority of people with not have symptoms of diverticulosis and most are diagnosed incidentally during tests such as colonoscopy or CT scan. Symptoms occur when diverticuli bleed or become infected and cause perforation or scarring and narrowing of the colon. It is not clear why some people develop problems and others do not. In general, it is encouraged to eat a diet high in fiber, fruits and vegetables, and low in red meat.
Diverticular bleeding is a common cause of lower GI bleeding. This occurs when the blood vessels close to the opening of the diverticulum becomes irritated and bleeds. Bleeding stops on its own 70% of the time. A colonoscopy is required to identify the source of bleeding and stop it as well as to look for other reasons why bleeding may occur, from a colon cancer for example. In rare cases when bleeding does not stop or cannot be controlled with other measures, that part of the colon must be removed.
Diverticulitis is an infection of a diverticulum. Just like in other places of the body, when infection occurs in the colon the body sets up an inflammatory response to attack the inflammation. This causes swelling and abdominal pain and can make a person feel generally sick. Simple diverticulitis is treated with antibiotics. Depending on the severity of pain or infection, hospital admission for supportive care may be needed. If a person does not improve with medical therapy or repeated attacks occur, surgery to remove that portion of the colon can be considered.
In some cases the infected diverticulum can perforate, called "perforated diverticulitis", resulting in collections of pus in the abdomen, or abscesses. A diverticular abscess is treated with a drainage procedure. When a perforation is large, stool leaks freely into the abdomen and emergency operation is required to remove the involved colon. Perforations can also result in connections, called "fistulas", to other organs such as the bladder or vagina. In these cases, surgery is often required to remove the involved colon and close the fistula.
Repeated infections over time cause the colon to become thick with scar tissue. Scar tissue can narrow the lining of the colon so that stool cannot freely pass through it. This is called a "diverticular stricture". A person may have symptoms of constipation, abdominal bloating, or bowel blockage. Often an operation is needed to remove a structured segment of colon.
It is important to note that cancer can mimic diverticulitis and it can be difficult to tell the difference between the two on CT scan. Whenever diverticulitis occurs, it is important to perform a colonoscopy after the person is well to inspect the lining of the colon and exclude the possibility of underlying cancer.
The surgical procedure performed for diverticulitis will vary depending on the exact circumstances surrounding each patient. In general, the colon is removed from the point of disease down to the top of the rectum. The colon may be reconnected. This procedure may or may not involve the creation of a colostomy or ileostomy. This procedure may be performed with an open technique or minimally invasive technique. Your colorectal surgeon will discuss the best available options with you.