A diverticulum is a saclike outpouching of the lining of the bowel that extends through a defect in the muscle layer. Diverticula may occur anywhere along the GI tract. Diverticulosis exists when mul-tiple diverticula are present without inflammation or symptoms. Diverticular disease of the colon is very common in developed countries, and its prevalence increases with age. More than 35% of Americans older than 60 years of age have diverticulosis. The incidence increases to 50% among those in the ninth decade of life (Keighley, 1999). Diverticulitis results when food and bacteria retained in a diverticulum produce infection and inflammation that can impede drainage and lead to perforation or abscess for-mation. Diverticulitis is most common (95%) in the sigmoid colon. Approximately 20% of patients with diverticulosis have di-verticulitis at some point. A congenital predisposition is suspected when the disorder occurs in those younger than 40 years of age. A low intake of dietary fiber is considered a predisposing factor, but the exact cause is unknown. Diverticulitis may occur in acute at-tacks or may persist as a continuing, smoldering infection. Most patients remain entirely asymptomatic. The symptoms manifested generally result from its potential complications—abscesses, fistu-las, obstruction, and hemorrhage.
A diverticulum forms when the mucosa and submucosal layers of the colon herniate through the muscular wall because of high intraluminal pressure, low volume in the colon (ie, fiber-deficient contents), and decreased muscle strength in the colon wall (ie, muscular hypertrophy from hardened fecal masses). Bowel contents can accumulate in the diverticulum and decompose, causing inflammation and infection. A diverticulum can become ob-structed and then inflamed if the obstruction continues. The in-flammation tends to spread to the surrounding bowel wall, giving rise to irritability and spasticity of the colon (ie, diverticulitis). Ab-scesses develop and may eventually perforate, leading to peritoni-tis and erosion of the blood vessels (arterial) with bleeding.
Chronic constipation often precedes the development of diver-ticulosis by many years. Frequently, no problematic symptoms occur with diverticulosis. Signs of acute diverticulosis are bowel irregularity and intervals of diarrhea, abrupt onset of crampy pain in the left lower quadrant of the abdomen, and a low-grade fever. The patient may have nausea and anorexia, and some bloating or abdominal distention may occur. With repeated local inflamma-tion of the diverticula, the large bowel may narrow with fibrotic strictures, leading to cramps, narrow stools, and increased con-stipation. Weakness, fatigue, and anorexia are common symp-toms. With acute diverticulosis, the patient reports mild to severe pain in the lower left quadrant. The condition, if untreated, can lead to septicemia.
A CT scan is the procedure of choice and can reveal abscesses. Ab-dominal x-ray findings may demonstrate free air under the di-aphragm if a perforation has occurred from the diverticulitis. Diverticulosis may be diagnosed using barium enema, which shows narrowing of the colon and thickened muscle layers. If there are symptoms of peritoneal irritation and when the diag-nosis is diverticulitis, barium enema is contraindicated because of the potential for perforation.
A colonoscopy may be performed if there is no acute diver-ticulitis or after resolution of an acute episode to visualize the colon, determine the extent of the disease, and rule out other con-ditions. Laboratory tests that assist in diagnosis include a com-plete blood cell count, revealing an elevated leukocyte count, and elevated sedimentation rate.
Complications of diverticulitis include peritonitis, abscess forma-tion, and bleeding. If an abscess develops, the associated findings are tenderness, a palpable mass, fever, and leukocytosis. An in-flamed diverticulum that perforates results in abdominal pain lo-calized over the involved segment, usually the sigmoid; local abscess or peritonitis follows. Abdominal pain, a rigid boardlike abdomen, loss of bowel sounds, and signs and symptoms of shock occur with peritonitis. Noninflamed or slightly inflamed diverticula may erode areas adjacent to arterial branches, causing massive rectal bleeding.
The incidence of diverticular disease increases with age because of degeneration and structural changes in the circular muscle layers of the colon and because of cellular hypertrophy. The symptoms are less pronounced in the elderly than in other adults. The elderly may not have abdominal pain until infection occurs. They may delay re-porting symptoms because they fear surgery or are afraid that they may have cancer. Blood in the stool is overlooked frequently, espe-cially in the elderly, because of a failure to examine the stool or the inability to see changes because of diminished vision.
Diverticulitis can usually be treated on an outpatient basis with diet and medicine therapy. When symptoms occur, rest, analgesics, and antispasmodics are recommended. Initially, the diet is clear liquid until the inflammation subsides; then, a high-fiber, low-fat diet is recommended. This type of diet helps to increase stool volume, decrease colonic transit time, and reduce intraluminal pressure. Antibiotics are prescribed for 7 to 10 days. A bulk-forming laxative also is prescribed.
In acute cases of diverticulitis with significant symptoms, hos-pitalization is required. Hospitalization is often indicated for those who are elderly, immunocompromised, or taking corticosteroids. Withholding oral intake, administering intravenous fluids, and in-stituting nasogastric suctioning if vomiting or distention occurs rests the bowel. Broad-spectrum antibiotics are prescribed for 7 to 10 days. An opioid is prescribed for pain relief; morphine is not used because it increases segmentation and intraluminal pressures. Oral intake is increased as symptoms subside. A low-fiber diet may be necessary until signs of infection decrease.
Antispasmodics such as propantheline bromide (Pro-Banthine) and oxyphencyclimine (Daricon) may be prescribed. Normal stools can be achieved by using bulk preparations (Metamucil) or stool softeners (Colace), by instilling warm oil into the rectum, or by in-serting an evacuant suppository (Dulcolax). Such a prophylactic plan can reduce the bacterial flora of the bowel, diminish the bulk of the stool, and soften the fecal mass so that it moves more easily through the area of inflammatory obstruction.
Although acute diverticulitis usually subsides with medical man-agement, immediate surgical intervention is necessary if complica-tions (eg, perforation, peritonitis, abscess formation, hemorrhage, obstruction) occur. Alternatively, when the acute episode of diver-ticulitis resolves, surgery may be recommended to prevent repeated episodes. Two types of surgery are considered:
• One-stage resection in which the inflamed area is removed and a primary end-to-end anastomosis is completed
• Multiple-staged procedures for complications such as ob-struction or perforation (Fig. 38-3)
The type of surgery performed depends on the extent of com-plications found during surgery. When possible, the area of di-verticulitis is resected and the remaining bowel is joined end to end (ie, primary resection and end-to-end anastomosis). This is performed through traditional surgical or laparoscopically as-sisted colectomy. A two-stage resection may be performed in which the diseased colon is resected (as in a one-stage procedure) but no anastomosis is performed; both ends of the bowel are brought out onto the abdomen as stomas. This “double-barrel” colostomy is then reanastomosed in a later procedure.
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