Typical symptoms of Crohn’s disease include abdominal pain, fever, diarrhea (possibly bloody), nausea, vomiting, anorexia, weight loss, and fatigue. Oral aphthous ulcers are a common but nonspecific occurrence in Crohn’s disease. In light of the fact that the terminal ileum and proximal colon are the most common areas of occurrence, abdominal pain often presents in the right lower quadrant and mimics appendicitis. The patient may present with disease complicated by fistula, bowel obstruction, bowel perforation with intra-abdominal abscess, liver disease, thromboembolism, nutritional deficiencies, and anemia related to malabsorption.

The clinical presentation of Crohn’s disease varies from mild to severe, and there are generally periods of remission and exacerbation. The disease is unpredictable. Patients with mild-to-moderate disease can tolerate a normal diet, are pain-free and not dehydrated, do not have bowel obstruction, and are nontoxic. Moderate-to-severe disease describes a patient who has failed treatment, is febrile, and has abdominal pain, nausea, vomiting, weight loss, and anemia. Severe/fulminant disease indicates a patient with ongoing symptoms despite treatment, bowel obstruction, rebound tenderness, profound weight loss, or perforation with abscess formation.8

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While moderate-to-severe symptoms generally prompt an evaluation that results in a finding of Crohn’s disease, several years may pass prior to diagnosis because the symptoms are often mild and nonspecific and mimic irritable bowel syndrome. In one study, the time between the development of symptoms and the diagnosis of the disease averaged 7.7 years.9-11

Once Crohn’s disease is considered, the diagnosis can be confirmed by colonoscopy and tissue biopsy. Typically, Crohn’s disease appears as discontinuous aphthous ulcerations, edema, and inflammation in the terminal ileum and colon.2 Unlike ulcerative colitis, which begins in the rectum and presents with a continuous area of inflammation, Crohn’s typically involves areas of diseased bowel interspersed with normal bowel and may not include the rectum.12 The presence of these “skip areas” is an important clue to differentiating between ulcerative colitis and Crohn’s.2

CT scanning is often the initial test in the workup of persistent abdominal pain, diarrhea, and other symptoms of Crohn’s disease. Terminal ileitis, patchy colitis, fistula and abscess formation are often identified via CT but can be absent with mild disease.2 An abnormality on CT prompts a colonoscopic evaluation to confirm the diagnosis. Small-bowel follow-through is often used to evaluate for the presence of disease of the small intestine.

Complications and extra-intestinal manifestations

The complications of Crohn’s disease can occur not only in the GI tract but also in extra-intestinal locations. Fistula formation Fistulas occur in up to 40% of patients and result from transmural inflammation that causes perforation and extension of a sinus tract, leading into adjacent organs or onto the skin.12 Fistulas often occur in the perianal area and present with leakage of stool onto the skin. The opening can be seen easily on physical examination. CT scanning can identify external fistulas, as well as communications between segments of bowel or between bowel and other organs.13 Fistulas leading into the bladder or vagina present with pneumaturia and fecal leakage from the vagina, respectively. Treatment involves medical management of underlying Crohn’s disease, antibiotics, and possibly surgery.

Bowel obstruction Bowel obstruction may be the initial impetus for the patient with undiagnosed Crohn’s to seek care.14 Obstruction is often due to edema resulting from the inflammatory reaction that occurs with an acute flare.

Obstruction may also occur secondary to stricture formation as a result of scar tissue from chronic disease.12 Presenting symptoms of bowel obstruction include nausea, vomiting (which can be feculent), and abdominal pain and distension. On examination, the abdomen is often distended and tympanic, with high-pitched or absent bowel sounds. Plain films of the abdomen show air-fluid levels, and CT scanning often identifies the area of obstruction.13 If the obstruction is inflammatory, medical treatment is warranted. If a fibrotic stricture is the culprit, bowel rest, nasogastric suction, and IV hydration may relieve symptoms in two to three days.12 When these are unsuccessful, surgery may be indicated.2 Sadly, surgery is not curative in Crohn’s disease, and >25% of patients undergoing a procedure will require a second procedure within five years.2