The term diverticular disease comes from the Latin word diverticulum, which means a “small diversion from the normal path.” The colon or large intestine is that part of the intestinal tract which stores residue for elimination from the body. The small blood vessels which supply blood to the large intestine or colon do so by penetrating the muscle coat of the colon, thereby producing a small defect through which the inner lining can protrude or herniate out. These small protrusions are called diverticulae.
The pressure created by muscle contractions of the left side (sigmoid) of the colon are considerably greater than those of the right side (ascending colon). This fact explains why diverticulae are more common on the left than right side of the colon. The prevalence of diverticulae clearly increases with age. While fairly uncommon during the first 4 decades of life, they reach a frequency of 50% in people greater than 65 years old.
It is very important to realize that the most common symptom produced by diverticulae is none! In other words, diverticular disease of the colon most often causes no difficulty and no symptoms. The presence of diverticulae without pain, inflammation, or bleeding is called diverticulosis. When the diverticulae cause symptoms, they can do so in one of two ways: first they can rupture into the abdominal cavity, cause localized irritation and inflammation, or produce an abscess. This is called acute diverticulitis. The suffix “itis” means inflammation. So an inflamed diverticulum is called diverticulitis. Patients who have diverticulitis often will describe the rather sudden onset of pain located in the lower left part of the abdomen over the sigmoid colon. It frequently is exquisitely tender and is associated with fever and a high white blood cell count. Alternatively, they can painlessly start to produce significant amounts of rectal bleeding. They very rarely bleed small amounts. When diverticulae bleed it is usually a rather large amount — a pint or more. This happens without any inflammation whatsoever. The cause is a weakening of the blood vessel adjacent to the diverticulum. What causes the weak wall is totally unknown.
Acute diverticulitis can frequently be diagnosed by a typical history and a physical exam showing impressive tenderness over the sigmoid colon, which is located in the left lower part of the abdomen. If fever and a high white blood cell count are present, this is seen as confirming the diagnosis. A barium enema or a lower GI x-ray are not useful in identifying this condition because the ruptured diverticulum is not seen on the x-ray. A CAT scan or ultrasound of the lower abdomen can be very helpful in showing an inflammatory mass over the sigmoid colon.
Diverticular bleeding can be a bit more difficult to diagnose and is frequently a “diagnosis of exclusion,” which refers to the fact that no other cause for the bleeding can be found except the diverticulae. It is correctly assumed that they were the culprit. Fortunately this is not common. Less than 5% of people with diverticular disease of the colon will bleed. Rarely, a bleeding or ulcerated diverticulum can be seen at the time of colonoscopy. Specialized x-ray procedures using isotopes tagged to a patient’s own red blood cells, or an x-ray procedure (angiogram) where a catheter and contrast material are injected into the arteries supplying the bleeding diverticulum are seen to leak contrast material from the bleeding diverticulum are utilized.
Acute diverticulitis is treated with antibiotics for 7-10 days. These antibiotics frequently have to be given intravenously. Diet is often severely limited during the first few days of treatment. Most patients will recover completely, but surgery is necessary for recurrent diverticulitis or perforation of the colon from diverticulitis. A colostomy is needed in cases of perforations. The colostomy can be reversed in 2-3 months. Bleeding diverticulosis is managed initially by monitoring the patient closely regarding his rate of blood loss and giving blood transfusions if necessary. Fortunately the bleeding normally stops. If not, the part of the colon containing the bleeding diverticulum needs to be surgically removed. This is often performed as an emergency operation.
There is much written but little proof that anything can be done to prevent a recurrence of bleeding diverticular disease of the colon or acute diverticulitis short of a surgical resection. Of those that have bled, about 15% will have a second bleed. If a second bleed occurs, the risks increase to 50% there will be a third. About 25% of those patients with acute diverticulitis will have a relapse. Many of these will need a surgical resection. The use of a high fiber diet or use of stool softeners has been advocated to prevent recurrences of this disease. The theory is that bulk in the colon in the form of a high fiber diet will help prevent recurrences by preventing localized high pressures from occurring. It is not known if this is helpful.