Diverticulosis is a condition in which the inner layer of the colon herniates (bulges out) through the outer, muscular layer, creating pouches called diverticula. Diverticulitis refers to inflammation and infection in one or more diverticula.
Description
Diverticula tend to occur most frequently in the last segment of the large intestine, the sigmoid colon. They occur with decreasing frequency toward the beginning of the colon. The chance of developing diverticula increases with age, so that by the age of 50, about 20–50% of all people will have some diverticula. By the age of 90, virtually everyone will have developed some diverticula. Most diverticula measure about 3 mm (0.19 inches) to just over 3 cm (1.18 inches) in diameter. Larger, or giant diverticula, are extremely rare, but may measure as large as 15 cm (5.9 inches) in diameter.
Causes and symptoms
Diverticula are believed to be caused by overly forceful contractions of the muscular wall of the large intestine, often caused by straining to produce a bowel movement. As areas of this wall spasm, they become progressively weaker, allowing the inner lining to bulge through. The anatomically weakest areas of the intestinal wall occur next to blood vessels which course through the wall, so diverticula commonly occur in this location.
Diverticula are most common in the developed countries of the West (North America, Great Britain, northern and western Europe). This is thought to be due to the diet of these countries, which tends to be low in fiber. This produces smaller volumes of stool. In order to move this smaller stool along the colon and out of the rectum, the colon must narrow itself significantly, and does so by contracting forcefully. This causes an increase in pressure, which, over time, weakens the muscular wall of the intestine and allows diverticular pockets to develop.
The origin of giant diverticula development is not completely understood; one theory involves gas repeatedly entering and becoming trapped in an already existing diverticulum, causing it to stretch and expand.
The great majority of people with diverticulosis will remain symptom-free. Many diverticula are incidentally discovered during examinations for other conditions of the intestinal tract.
Some patients with diverticulosis have symptoms such as constipation, cramping, and bloating. It is unclear whether these symptoms are actually caused by the diverticula themselves, or whether some other gastrointestinal condition, such as irritable bowel syndrome, might be responsible. Because many diverticula develop in areas near blood vessels, one serious, although infrequent, risk of diverticulosis is intestinal bleeding. Seventy-five percent of such bleeding episodes occur in diverticula located on the right side of the colon. About 50% of the time the bleeding will stop on its own.
One of the most common and potentially serious complications of diverticulosis is inflammation and infection of a particular diverticulum, a condition called diverticulitis. Diverticulitis is usually found in the sigmoid colon, the final segment of the large intestine that empties into the rectum where most diverticula are found. Older adults have the most serious complications from diverticulitis, although very severe infections also may occur in patients under the age of 50. Men are three times as likely as women to be stricken with diverticulitis.
Diverticulitis is believed to occur when a hardened piece of stool, undigested food, and bacteria (called a fecalith) becomes lodged in a diverticulum. This blockage interferes with the blood supply to the area, and infection sets in.
The patient with diverticulitis experiences pain (especially in the lower left side of the abdomen) and fever. In response to the infection and the irritation of nearby tissues within the abdomen, the abdominal wall muscles may begin to spasm. About 25% of all patients with diverticulitis have some rectal bleeding, although this rarely becomes severe. Abscesses (pockets of infection) may appear within the wall of the intestine, or even on the exterior surface of the intestine. When a diverticulum weakens sufficiently, and is filled to bulging with pus, a perforation in the intestinal wall may develop. When the infected contents of the intestine spill into the abdomen, peritonitis may occur. Other complications of diverticulitis include the formation of fistulas and colonic strictures.
Diagnosis
The majority of diverticula do not cause any symptoms, and are often found during an examination being performed for some other medical condition. When diverticula are suspected because a patient begins to have sudden rectal bleeding, the location of the bleeding can be identified with colonoscopy. In this procedure a colonoscope, a small, flexible tube, is inserted through the rectum and into the colon. The tip of the scope has a fiber-optic camera, which allows the view through this colonoscope to be projected onto a television screen. The operator can introduce the colonoscope through the entire colon to find the source of the bleeding.
Angiography can also trace the source of intestinal bleeding, although it is used less often. It involves inserting a tiny tube through the femoral artery in the groin, and advancing it into one of the major arteries that supplies the colon. Contrast medium that will appear on xray films is injected, and the area of bleeding is located by looking for an area where the contrast is leaking into the lumen of the colon.
Diagnosis of diverticulitis is not difficult in patients with previously diagnosed diverticulosis. The presence of left-lower quadrant abdominal pain and fever in such patients should prompt suspicion of diverticulitis. Examination of the abdomen will usually reveal tenderness to touch, with the patient's abdominal muscles contracting strongly to protect the tender area.
During a rectal exam, the clinician may be able to feel an abnormal mass if there has been perforation and abscess formation at the site of the perforation. Palpating this mass may prove painful to the patient.
When diverticulitis is the suspected cause of the patient's symptoms, tests traditionally used to diagnose colonic disorders such as barium enema and endoscopy are contraindicated during the acute phase of the illness. The concern is that the increased pressure exerted on the colon during these exams may increase the likelihood of perforation of the diverticula. After several weeks, when the diverticulitis has resolved, these examinations may be performed in order to confirm the diagnosis and extent of the disease.
Treatment
Only about 20% of patients with diverticulosis experience symptoms that prompt them to seek medical care. Most people never know that they have diverticula. For those individuals with cramping pain and constipation due to diverticulosis, the usual treatment involves increasing the fiber in the diet. This may be done with dietary supplements of bran or psyllium seed to increase stool volume, or by increasing the patient's intake of fruits, vegetables, legumes, and whole-grain foods. Bleeding diverticula are usually treated by bed rest, with blood transfusion if needed for hemorrhaging. In cases of very heavy hemorrhaging, medications to encourage clotting may be injected during the course of a diagnostic angiography.
While there are almost no situations when uncomplicated diverticulosis requires surgery, giant diverticula always require removal due to the high risk of infection and perforation. The usual treatment involves removing that portion of the intestine.
Treatment for uncomplicated diverticulitis usually requires hospitalization to rest the bowel. This involves keeping the patient from eating and drinking anything. The patient receives IV (intravenous) fluids and antibiotics. Some physicians treat mildly ill patients at home with a liquid-only diet and oral antibiotics.
The complications of diverticulitis need to be treated aggressively, because mortality (death rate) from perforation and peritonitis is quite high. Abscesses may be drained of their infected contents by inserting a needle through the skin of the abdomen and into the abscess. If this is unsuccessful, laparotomy (open abdominal surgery) is required to resect the segment of the colon that contains the abscess. Fistulas require surgical repair by removing a segment of the colon that contains the origin of the fistula, followed by immediate anastomosis (reconnection) of the two free ends of colon. Peritonitis requires open surgery. The entire abdominal cavity is irrigated (washed) with a warmed sterile saltwater solution, and the damaged piece of intestine is removed. Obstructions require immediate surgery to prevent perforation. Massive, uncontrollable bleeding is rare, and may require removal of part or all of the large intestine.
During any of these procedures, the surgeon must decide how much of the intestine must be removed. When the amount of intestine removed is great, it may be necessary to perform a colostomy, which involves pulling the end of the remaining intestine through the abdominal wall, to the outside. This bit of intestine is then fashioned so that a bag can be fitted over it. The patient's feces collect in the bag, because the intestine no longer connects with the rectum. The colostomy may be temporary, in which case another operation will be required to reconnect the intestine, after substantial healing has occurred. Otherwise the colostomy is permanent, and the patient must adjust to living permanently with the colostomy bag. Most patients with colostomies are able to lead full, active lives.
Occasionally, a patient has such severe diverticular disease that the surgeon recommends removal of a portion of the colon as a preventive measure, to avoid the high risk of surgery performed after a complication has set in. It is recommended for patients identified as at very high risk of experiencing dangerous complications of diverticulosis. Such elective surgery may be recommended:
for older patients who have had several attacks of diverticulitis
for patients under age 50 who have had even one attack
when treatment does not get rid of a painful mass
when the intestine appears to be strictured on colonoscopic or barium enema (This could suggest the presence of cancer.)
when certain patients begin to regularly experience painful urination or urinary infections (this suggests that there may be a connection between the intestine and the bladder)
when there is any question of cancer
when the diverticular disease appears to be progressing rapidly
Prognosis
The prognosis for people with diverticula is excellent, with only 20% of such patients ever seeking any medical care for their condition.
While diverticulitis can be a difficult and painful disease, it is usually quite treatable. Prognosis is worse for individuals who have coexisting medical problems, particularly those requiring the use of steroids, which increase the chances of developing a serious infection. Prognosis is also worse in the elderly.
Health care team roles
Diverticulitis and diverticulosis are often diagnosed by primary care practitioners and gastroenterologists during the course of examinations for other problems. In some instances, patients may require surgical intervention. Imaging studies to assist in diagnosis are performed by x-ray technologists; laboratory technologists may be involved in obtaining blood and stool samples for analysis.
Patient education
Nurses, dietitians, and nutritional counselors have important roles in teaching patients about dietary
KEY TERMS
Angiography—An x-ray study of the arteries in a particular part of the body. Angiography is often performed in order to localize internal bleeding.
Bowel obstruction—A blockage in the intestine which prevents the normal flow of waste down the length of the intestine.
Colonic stricture—Strictures that form after a bout of diverticulitis resolves, leaving scar tissue that narrows the colon lumen.
Colostomy—A procedure performed when a large quantity of intestine is removed. The end piece of the intestine leading to the rectum is closed.
Diverticula—Outpouchings in the large intestine caused when the inner, lining layer of the large intestine (colon) bulges out (herniates) through the outer, muscular layer.
Endoscopy—Examination of an area of the gastrointestinal tract by putting a lighted scope, usually bearing a fiber-optic camera, into the rectum, and passing it through the intestine.
Fistula—An abnormal connection formed between two organs which usually have no connection whatsoever (e.g. the colon and bladder).
Peritonitis—A potentially life-threatening infection and inflammation of the lining of the abdominal cavity, the peritoneum.
Sigmoid colon—The final portion of the large intestine which empties into the rectum.
changes to prevent these conditions. Nurses, social workers, and ostomy specialists also may be involved in educating patients pre- and postoperatively about colostomy care.
Prevention
While there is no absolutely certain way to prevent the development of diverticula, it is believed that high-fiber diets are beneficial. Foods recommended for their high-fiber content include whole-grain breads and cereals, and all types of fruits and vegetables. Most experts suggest that individuals consume about 20–35 grams of fiber daily. If this is not possible to achieve through diet, there are fiber products that can be mixed into 8 ounces of water or juice, and which provide about 4–6 grams of fiber per dose.
BOOKS
Isselbacher, Kurt J., and Alan Epstein. "Diverticular, Vascular, and Other Disorders of the Intestine and Peritoneum." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998.
PERIODICALS
Cerda, James J., et al. "Diverticulitis: Current Management Strategies." Patient Care 31 no. 12 (July 15, 1997): 170 ff.
Cunningham, Mark A., et al. "Medical Versus Surgical Management of Diverticulitis in Patients Under Age 40." American Journal of Surgery 174 no. 6 (December 1997): 733 ff.
"Diet and Diverticular Disease in Men." Nutrition Research Newsletter 14 no. 2 (November 1994): 28.
"Diet for Diverticulosis."Consumer Reports on Health 8, no. 11 (November 1996): 132.
Munson, Marty, and Teresa Yeykal. "Outrun Trouble: Running and Bran Cereal in the Prevention of Diverticular Disease." Prevention 47 no. 9 (September 1995): 38 ff.
ORGANIZATIONS
National Digestive Diseases Information Clearinghouse. 2 Information Way, Bethesda, MD, 20892-3570.
