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Gastrointestinal and Hepatobiliary Function

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left quadrant, accompanied by nausea and vomiting, tenderness in the lower left quadrant, a slight fever, and an elevated white blood cell count. These symptoms usually last for several days, unless complications occur, and usually are caused by localized inflammation of the diverticula with perforation and development of a small, localized abscess. Complications include perfora- tion with peritonitis, hemorrhage, and bowel obstruc- tion. Fistulas can form, usually involving the bladder (i.e., vesicosigmoid fistula) but sometimes involving the skin, perianal area, or small bowel. Pneumaturia (i.e., air in the urine) is a sign of vesicosigmoid fistula. The diagnosis of diverticular disease is based on his- tory and presenting clinical manifestations. 39 The dis- ease may be confirmed by CT scans or ultrasonographic studies. CT scans are the safest and most cost-effective method. Because of the risk of peritonitis, barium enema studies and endoscopy should be avoided in persons who are suspected of having acute diverticulitis. Flat abdominal radiographs may be used to detect complica- tions associated with acute diverticulitis. The usual treatment for diverticular disease is to prevent symptoms and complications. This includes increasing the bulk in the diet and bowel retraining so that the person has at least one bowel movement each day. The increased bulk promotes regular defecation and increases colonic contents and colon diameter, thereby decreasing intraluminal pressure. Acute diverticulitis is treated by withholding solid food and administering a broad-spectrum antibiotic. Hospitalization may be required for persons who show significant inflamma- tion, are unable to tolerate oral fluids, or have signifi- cant comorbid conditions. Surgical treatment is reserved for complications. Appendicitis Acute appendicitis, or inflammation of the wall of the appendix, is extremely common. It is seen most fre- quently in the 20- to 30-year-old age group, but it can occur at any age. 6 The appendix becomes inflamed, swollen, and gangrenous, and it eventually perforates if not treated. 41 Although the cause of appendicitis is unknown, it is thought to be related to intraluminal obstruction with a fecalith (i.e., hard piece of stool) or to twisting. Appendicitis usually has an abrupt onset, with pain referred to the epigastric or periumbilical area. This pain is caused by stretching of the appendix during the early inflammatory process. At approximately the same time that the pain appears, there are one or two episodes of nausea. Initially, the pain is vague, but over a period of 2 to 12 hours, it gradually increases and may become colicky. When the inflammatory process has extended to involve the serosal layer of the appendix and the peri- toneum, the pain becomes localized to the lower right quadrant. There usually is an elevation in temperature and a white blood cell count greater than 10,000/mm 3 , with 75% or more polymorphonuclear cells. Palpation of the abdomen usually reveals a deep tenderness in

Stomach

Large intestine (colon)

Small intestine

Diverticula

Ileum

Rectum Anus

Sigmoid colon

FIGURE 29-8. Location of diverticula in the sigmoid colon.

layer cause the intestine to bulge outward into pouches called haustra. Diverticula develop between the longi- tudinal muscle bands of the haustra, in the areas where blood vessels pierce the circular muscle layer to bring blood to the mucosal layer. An increase in intraluminal pressure in the haustra provides the force for creating these herniations. Most people with diverticular disease remain asymp- tomatic. 38,39 The disease often is found when x-ray studies are done for other purposes. Ill-defined lower abdominal discomfort, a change in bowel habits (e.g., diarrhea, constipation), bloating, and flatulence are common. Diverticulitis is a complication of diverticulo- sis in which there is inflammation and gross or micro- scopic perforation of the diverticula. 40 One of the most common complaints of diverticulitis is pain in the lower

FIGURE 29-9. Diverticulosis of the colon.The colon was inflated with formalin.The mouths of numerous diverticula are seen between the taenia (arrows).There is a blood clot protruding from the mouth of one of the diverticula (arrow). (From Rubin R.The gastrointestinal tract. In: Rubin R, Strayer DS, eds. Rubin’s Pathophysiology: Clinicopathologic Foundations of Medicine. 6th ed. Philadelphia, PA: Wolters Kluwer Health | Lippincott Williams &Wilkins; 2012:652.)