eMedicine Specialties > Emergency Medicine > Gastrointestinal

Inflammatory Bowel Disease

Author: William Shapiro, MD, Consulting Staff, Department of Urgent Care and Emergency Medicine, Scripps Clinic and Research Foundation
Contributor Information and Disclosures

Updated: Apr 25, 2008

Introduction

Background

Inflammatory bowel disease (IBD) commonly refers to ulcerative colitis (UC) and Crohn disease (CD), which are chronic inflammatory diseases of the GI tract of unknown etiology. Crohn disease is also referred to as regional enteritis, terminal ileitis, or granulomatous ileocolitis.

Pathophysiology

Increasing evidence suggests that, at least in CD, there is a defect in the function of the intestinal immune system. As a consequence, there is a breakdown of the defense barrier of the gut, which, in turn, results in exposure of the mucosa to microorganisms or their products. The result is a chronic inflammatory process mediated by T cells. Hence, therapy should be directed at improving the intestinal immune system. It has been postulated that genetic factors may predispose certain individuals to developing a "leaky gut."

In UC, inflammation always begins in the rectum, extends proximally a certain distance, and then abruptly stops. A clear demarcation exists between involved and uninvolved mucosa. The rectum is always involved in UC, and no "skip areas" are present. UC primarily involves the mucosa and the submucosa, with formation of crypt abscesses and mucosal ulceration. The mucosa typically appears granular and friable. In more severe cases, pseudopolyps form, consisting of areas of hyperplastic growth with swollen mucosa surrounded by inflamed mucosa with shallow ulcers. In severe UC, inflammation and necrosis can extend below the lamina propria to involve the submucosa and the circular and longitudinal muscles, although this is unusual.

UC remains confined to the rectum in approximately 25% of cases. In the remainder of cases, UC spreads proximally and contiguously. Pancolitis occurs in 10% of patients. The small intestine is never involved, except when the distal terminal ileum is inflamed in a superficial manner, referred to as backwash ileitis. Even with less than total colonic involvement, the disease is strikingly and uniformly continuous. As the disease becomes chronic, the colon becomes a rigid foreshortened tube that lacks its usual haustral markings, leading to the lead pipe appearance observed on barium enema. The skip areas (ie, normal areas of the bowel interspersed with diseased areas) observed in CD of the colon do not occur in UC.

CD, on the other hand, consists of segmental involvement by a nonspecific granulomatous inflammatory process. The most important pathologic feature is involvement of all layers of the bowel, not just the mucosa and the submucosa, as is characteristic of UC.

Furthermore, CD is discontinuous, with skip areas interspersed between one or more involved areas. Late in the disease, the mucosa develops a cobblestone appearance, which results from deep longitudinal ulcerations interlaced with intervening normal mucosa. The 3 major patterns of involvement in CD are (1) disease in the ileum and cecum, occurring in 40% of patients; (2) disease confined to the small intestine, occurring in 30% of patients; and (3) disease confined to the colon, occurring in 25% of patients. Rectal sparing is a typical but not constant feature of CD. However, anorectal complications (eg, fistulas, abscesses) are common. Much less commonly, CD involves the more proximal parts of the GI tract, including the mouth, tongue, esophagus, stomach, and duodenum. CD causes 3 patterns of involvement: (1) inflammatory disease, (2) strictures, and (3) fistulas.

UC and CD are generally diagnosed using clinical, endoscopic, and histologic criteria. However, no single finding is absolutely diagnostic for one disease or the other. Furthermore, approximately 20% of patients have a clinical picture that falls between CD and UC; they are said to have indeterminate colitis.

The incidence of gallstones and kidney stones is increased in CD because of malabsorption of fat and bile salts. Gallstones are formed because of increased cholesterol concentration in the bile, caused by a reduced bile salt pool. Patients who have CD with ileal disease or resection also are likely to form calcium oxalate kidney stones. With the fat malabsorption, unabsorbed long-chain fatty acids bind calcium in the lumen. Oxalate in the lumen normally is bound to calcium. Calcium oxalate is poorly soluble and poorly absorbed; however, if calcium is bound to malabsorbed fatty acids, oxalate combines with sodium to form sodium oxalate, which is soluble and is absorbed in the colon (enteric hyperoxaluria). The development of calcium oxalate stones in CD requires an intact colon to absorb oxalate. Patients with ileostomies do not develop calcium oxalate stones.

Extraintestinal manifestations of IBD include iritis, episcleritis, arthritis, and skin involvement, as well as pericholangitis and sclerosing cholangitis.

Frequency

United States

The incidence is 70-150 cases per 100,000 individuals.

Mortality/Morbidity

The quality of life generally is lower with CD than with UC, in part because of recurrences after surgery performed for CD.

• The most common causes of death in IBD are peritonitis with sepsis, malignancy, thromboembolic disease, and complications of surgery.
• Toxic megacolon, one of the most dreaded complications of UC, can lead to perforation, sepsis, and death.
• Malnutrition and chronic anemia are observed in long-standing CD.
• Children with CD or UC can exhibit growth retardation.

Race

• Incidence among whites is approximately 4 times that of other races.
• IBD is observed most commonly in Northern Europe and North America. It is a disease of industrialized nations.
• Incidence is higher in Ashkenazi Jews (ie, those who have immigrated from Northern Europe) than in other groups.

Sex

Incidence is slightly greater in females than in males.

Age

• Incidence peaks in the second and third decades of life.
• A second smaller peak occurs in patients aged 55-65 years.
• CD and UC can occur in childhood, although the incidence is much lower in children younger than 15 years.

Clinical

History

• Patients with ulcerative colitis (UC) most commonly present with bloody diarrhea, whereas patients with Crohn disease (CD) usually present with nonbloody diarrhea.
  • Abdominal pain and cramping, fever, and weight loss occur in more severe cases.
  • The greater the extent of colon involvement, the more likely the patient is to have diarrhea.
  • Rectal urgency or tenesmus reflects reduced compliance of the inflamed rectum.
  • Patients might have formed stools if their disease is confined to the rectum.
  • As the degree of inflammation increases, systemic symptoms develop, including low-grade fever, malaise, nausea, vomiting, sweats, and arthralgias.
  • Fever, dehydration, and abdominal tenderness develop in severe UC, reflecting progressive inflammation into deeper layers of the colon.
• The presentation of CD is generally more insidious than that of UC, with ongoing abdominal pain, anorexia, diarrhea, weight loss, and fatigue.
  • Grossly bloody stools, while typical of UC, are less common in CD.
  • Stools may be formed, but loose stools predominate if the colon or the terminal ileum is involved extensively.
  • One half of patients with CD present with perianal disease (eg, fistulas, abscesses).
  • Occasionally, acute right lower quadrant pain and fever may be noted, mimicking appendicitis.
  • Commonly, the diagnosis is established only after several years of recurrent abdominal pain, fever, and diarrhea.
• CD with gastroduodenal involvement may mimic peptic ulcer disease and can progress to gastric outlet obstruction.
• Many patients with inflammatory bowel disease (IBD) have irritable bowel syndrome, which can produce occasional cramping, irregular bowel habits, and passage of mucus without blood or pus.
• Weight loss is observed more commonly in CD than in UC because of the malabsorption associated with small bowel disease. Patients may reduce their food intake in an effort to control their symptoms.
• Systemic symptoms are common and include fever, sweats, malaise, and arthralgias. A low-grade fever may be first warning sign of a flare.
• Recurrences may occur with emotional stress, infections or other acute illnesses, pregnancy, dietary indiscretions, use of cathartics or antibiotics, or withdrawal of anti-inflammatory or steroid medications.
• Children may present with growth retardation and delayed or failed sexual maturation.
• In 10-20% of cases, patients present with extraintestinal manifestations, including arthritis, uveitis, or liver disease.

Physical

• Fever, tachycardia, dehydration, and toxicity may occur. Pallor may be noted, reflecting anemia. The magnitude of these factors is related directly to the severity of the attack.
• Evaluate for signs of localized peritonitis, although abdominal tenderness is common. Patients with toxic megacolon appear septic. They have high fever; lethargy; chills; tachycardia; and increasing abdominal pain, tenderness, and distention.
• Patients with CD may develop a mass in the right lower quadrant.
• The rectal examination often reveals bloody stool on gross or Hemoccult examination.
• Complications (eg, perianal fissures or fistulas, abscesses, rectal prolapse) may be observed in up to 90% of patients with CD.
• Include in the examination a search for extraintestinal manifestations, such as iritis, episcleritis, arthritis, and dermatologic involvement. Distinguishing Features of CD Versus UC

  Open table in new window

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  Table

  Features	Crohn Disease	Ulcerative Colitis
  Skip areas	Common	Never
  Cobblestone mucosa	Common	Rare
  Transmural involvement	Common	Occasional
  Rectal sparing	Common	Never
  Perianal involvement	Common	Never
  Fistulas	Common	Never
  Strictures	Common	Occasional
  Granulomas	Common	Occasional

  Features	Crohn Disease	Ulcerative Colitis
  Skip areas	Common	Never
  Cobblestone mucosa	Common	Rare
  Transmural involvement	Common	Occasional
  Rectal sparing	Common	Never
  Perianal involvement	Common	Never
  Fistulas	Common	Never
  Strictures	Common	Occasional
  Granulomas	Common	Occasional

Causes

The etiology of IBD is unknown. Environmental, infectious, genetic, autoimmune, and host factors have been suspected. Interactions among these factors may be more important.

The risk of developing UC is higher in nonsmokers and former smokers than in current smokers. The onset of UC occasionally appears to coincide with smoking cessation. This does not imply that smoking would improve the symptoms of UC. Interestingly, some success in the use of nicotine patches has been reported. On the contrary, patients with CD have a higher incidence of smoking than the general population, and those patients with CD who continue to smoke appear to be less likely to respond to medical therapy.

• Inflammatory mediators
  • Interleukin-1
  • Tumor necrosis factor–alpha (TNF-alpha)
• Aggravation by bacterial infection and inflammatory cascade
• Positive family history: The most important risk factor for developing IBD is a positive family history.

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