Diverticular Disease of the Colon.docx

Diverticular Disease of the Colon Diverticula are herniations or saclike outpouchings of mucosa through the muscle layers of the colon wall. Diverticulosis is asymptomatic diverticular disease. Diverticulitis represents inflammation. The cause of diverticular disease is unknown. Approximately 300,0...

Diverticular Disease of the Colon Diverticula are herniations or saclike outpouchings of mucosa through the muscle layers of the colon wall. Diverticulosis is asymptomatic diverticular disease. Diverticulitis represents inflammation. The cause of diverticular disease is unknown. Approximately 300,000 hospital admissions per year are related to diverticular disease.110 Predisposing factors include older age, genetic predisposition, obesity, smoking, diet, lack of physical activity, and medication use, such as aspirin and nonsteroidal antiinflammatory drugs. Lack of dietary fiber may or may not contribute to diverticular disease.111 Altered intestinal microbiota, visceral hypersensitivity, and abnormal colonic motility also may be contributing factors.112 Pathophysiology. Diverticula can occur anywhere in the gastrointestinal tract, with the most common sites in the left colon (prevalent in Western countries) and the right colon (prevalent in Asian countries). They rarely occur in the small intestine113 and are associated with increased intracolonic pressure, abnormal neuromuscular function, and alterations in intestinal motility. The diverticula form at weak points in the colon wall, where arteries penetrate the tunica muscularis to nourish the mucosal layer. The colonic mucosa herniates through the smooth muscle layers (Fig. 42.14). A common associated finding is thickening of the circular and longitudinal (teniae coli) muscles surrounding the diverticula. Increased collagen and elastin deposition, not muscle hypertrophy, is associated with wall thickening and contributes to increased intraluminal pressure and herniation. Habitual consumption of a low-residue diet reduces fecal bulk, thus reducing the diameter of the colon. According to Laplace\'s law (see Chapter 32), wall pressure increases as the diameter of a cylindrical structure decreases. Therefore pressure within the narrow lumen can increase enough to cause local ischemia and rupture the diverticula. However, the exact cause of diverticula is uncertain. Clinical Manifestations. Symptoms of uncomplicated diverticular disease are usually vague or absent. Cramping pain of the lower abdomen can accompany constriction of the thickened colonic wall. Diarrhea, constipation, distention, or flatulence may occur. If the diverticula become inflamed or abscesses form, the individual develops fever, leukocytosis (increased white blood cell count), and tenderness of the lower left quadrant. Evaluation and Treatment. Diverticula are often discovered during diagnostic procedures performed for other problems. Ultrasound, sigmoidoscopy, or colonoscopy permits direct observation of the lesions. Abdominal computed tomography (CT) is used for complicated cases. An increase of dietary fiber intake increases stool weight, lowers colonic pressures, improves transit times, and often relieves symptoms, although data are lacking (see Nutrition & Disease: Diverticular Disease and Diet). Uncomplicated diverticular disease is treated with bowel rest and analgesia. Antibiotics (i.e., rifaximin) and surgical resection are used to treat severe disease.114 Radiographic, endoscopic, and laparoscopic procedures are implemented for more severe complications, including hemorrhage, bowel stenosis, obstruction, abscesses, fistulae, bowel perforation, and peritonitis.115,116 Nutrition & Disease Diverticular Disease and Diet Daily consumption of fiber-enriched foods is being re-evaluated for the prevention of diverticula. A high-fiber diet increases fecal bulk, decreases transit time, lowers intracolonic pressures, and eases stool elimination. The recommendation for fiber has been 20 to 35 g/day. Some examples of high-fiber choices are whole wheat bread and other grain products, baked potato with skin, fresh fruit with skins, raw vegetables, beans, peas, legumes, wheat bran, and brown rice. Side effects may include flatulence, intestinal rumbling, cramps, and diarrhea and the possibility that frequent bowel movements promote a greater prevalence of diverticular disease. A gradual increase in dietary fiber over 1 or 2 months helps to avoid these problems. Other potential problems with an excessively high-fiber diet (greater than 40 to 45 g) might include a decrease in nutrient absorption because of the increased volume of intestinal contents, which in turn decreases the ability of the digestive enzymes to come into contact with the food. An increase of water intake (eight 8-ounce glasses) is important so intestinal blockage will not occur. For small children and older adults, a high-fiber diet increases the volume of food needed to meet energy requirements, and that increase may be difficult to obtain. Although some physicians recommend restricting nuts, seeds, and foods containing seeds such as berries, kiwi, and tomatoes that might lodge in the pouches, there is no evidence that this happens. If the diverticula become inflamed, a low-fiber, low-residue (no milk products), or elemental diet, or in complicated cases total parenteral nutrition (TPN), is required to prevent continued irritation of the inflamed tissue. Controlled clinical trials are needed to evaluate the effectiveness of high-fiber diets in preventing diverticular disease. The efficacy of probiotics in modifying gut microbiota and relieving symptoms of diverticular disease also requires more investigation.