Crohn’s disease is an inflammation of the alimentary tract characterized by exacerbations and remissions. It can affect any portion of the tract from the mouth to the anus. In 50% of cases, the disease involves the colon and small bowel. About 33% of cases involve the terminal ileum, and 10% to 20% of cases involve only the colon. The disease can extend through all layers of the intestinal wall and may also involve regional lymph nodes and the mesentery.
Crohn’s disease is most prevalent in adults ages 20 to 40. It’s two to three times more common in people of Jewish ancestry and least common in blacks.
Although the exact cause of Crohn’s disease is unknown, possible causes include allergies and other immune disorders and infection. However, no infecting organism has been isolated. A genetic cause has also been implicated in some cases.
As the disease progresses, deep ulcers and fissures extend into muscle layers of the wall. These lesions give rise to characteristic “cobblestone” appearance.
Whatever the cause of Crohn’s disease, lacteal blockage in the intestinal wall leads to edema and, eventually, to mucosal inflammation, ulceration, stricturing, and fistula and abscess formation. Absorption is impaired and small bowel obstruction may result.
Signs and symptoms
Clinical effects vary according to the location and extent of the inflammation.
Acute inflammatory signs and symptoms mimic appendicitis and include steady, colicky, pain in the right lower quadrant; cramping; tenderness; flatulence; nausea; fever; and diarrhea. Bleeding may occur and, although usually mild, may be massive. Bloody stool may also occur.
Chronic symptoms are more typical of the disease, with complaints of abdominal distention and crampy abdominal pain. Symptoms may include a low-grade fever, weight loss, fatigue, and weakness. Diarrhea is usually nonbloody and intermittent, with right lower quadrant or periumbilical pain.