Porth's Essentials of Pathophysiology, 4e

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Disorders of Gastrointestinal Function

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colon (pancolitis). The inflammatory process tends to be confluent and continuous instead of skipping areas, as it does in Crohn disease. Characteristic of the disease are lesions that form in the crypts of Lieberkühn in the base of the mucosal layer (see Chapter 28, Fig. 28-11). The inflammatory process leads to the formation of pinpoint mucosal hemor- rhages, which in time suppurate and develop into crypt abscesses. These inflammatory lesions may become necrotic and ulcerate. Although the ulcerations usually are superficial, they often extend to nearby tissues, caus- ing large denuded areas (Fig. 29-7). As a result of the inflammatory process, the mucosal layer often develops tonguelike projections that resemble polyps and there- fore are called pseudopolyps. The bowel wall thickens in response to repeated episodes of colitis. Clinical Manifestations. Ulcerative colitis typically presents as a relapsing disorder marked by attacks of diarrhea. The diarrhea may persist for days, weeks, or months and then subside, only to recur after an asymptomatic interval of several months to years or even decades. 8,29,30 Because ulcerative colitis affects the mucosal layer of the bowel, the stools typically contain blood and mucus. Nocturnal diarrhea usually occurs when daytime symptoms are severe. There may be mild abdominal cramping and fecal incontinence. Anorexia, weakness, and fatigability are common. Based on clinical and endoscopic findings, the disease is characterized by its severity and extent. Severity is defined as mild, moderate, or severe. 8 The most common form of the disease is the mild form, in which the person has less than four formed or liquid stools daily, with intermittent rectal bleeding. Because of rectal inflamma- tion there may be urgency, accompanied by lower left quadrant cramping. Persons with moderate disease have more severe diarrhea and bleeding. Abdominal pain and tenderness may be present, but not severe. There may

be fever and anemia. Persons with severe disease have more than 6 bloody bowel movements a day, resulting in severe anemia, hypovolemia, and impaired nutrition with hypoalbuminemia. A subset of persons with ulcer- ative colitis develop a more fulminant form of the dis- ease with rapid progression over a matter of weeks to fever, prominent hypovolemia, hemorrhaging requiring transfusion, and abdominal distention with tenderness. Complications. Cancer of the colon is one of the feared complications of ulcerative colitis. 6–8,29 Because of the relatively high risk for development of cancer, regular annual or biannual surveillance colonoscopies with multiple biopsies are recommended for persons with extensive colitis, beginning 8 to 10 years after diagnosis. Diagnosis and Treatment. Diagnosis of ulcerative colitis is based on history and physical examination. The diagnosis usually is confirmed by sigmoidoscopy, colonoscopy, biopsy, and negative stool examinations for infectious or other causes. Colonoscopy should not be performed on persons with severe disease because of the danger of perforation, but may be performed after demonstrated improvement to determine the extent of disease and need for subsequent cancer surveillance. 8,29,30 Treatment depends on the extent of the disease and severity of symptoms. It includes measures to control the acute manifestations of the disease and prevent recurrence. Some people with mild to moderate symp- toms are able to control their symptoms simply by avoiding caffeine, lactose (milk), highly spiced foods, and gas-forming foods. Fiber supplements may be used to decrease diarrhea and rectal symptoms. Surgical treatment (i.e., removal of the rectum and entire colon) with the creation of an ileostomy or ileoanal anastomo- sis may be required for persons who do not respond to medications and conservative methods of treatment. The medications used in treatment of ulcerative colitis are similar to those used in the treatment of Crohn dis- ease. They include the nonabsorbable 5-ASA compounds (e.g., sulfasalazine, mesalamine). 8,29,30 The corticosteroids are used selectively to lessen the acute inflammatory response. Many of these medications can be administered rectally by suppository or enema. Immunomodulating drugs and anti-TNF therapies may be used to treat per- sons with severe colitis. Unlike Crohn disease, ulcerative colitis may respond to probiotic (oral preparations of bacteria contained in the normal gut flora) therapy. 29 Infectious Enterocolitis A number of microbial agents, including viruses, bacte- ria, and protozoa, can infect the gastrointestinal tract, causing a broad range of symptoms including diar- rhea, abdominal pain, perianal discomfort, ulceration, and hemorrhage. Infectious enterocolitis is a global problem, causing more than 3 million deaths annually and accounting for up to one half of deaths in children younger than 5 years in some countries. 6 Although less common in industrialized countries, these disorders still

FIGURE 29-7. Ulcerative colitis. Prominent erythema and ulceration of the colon begin in the ascending colon and are most severe in the rectosigmoid area (From Rubin R.The gastrointestinal tract. In: Rubin R, Strayer DS, eds. Rubin’s Pathology: Clinicopathologic Foundations of Medicine. 6th ed. Philadelphia, PA: Wolters Kluwer Health | Lippincott Williams & Wilkins; 2012:656.)