Differentials
Crohn disease
SIGNS / SYMPTOMS
Signs and symptoms are similar to those of UC. Crohn disease often has perianal involvement, rectal sparing, and a tendency to form fistulae.
INVESTIGATIONS
Endoscopy and biopsy. Distinguished from UC by inflammation that extends deep to the muscularis mucosae, the presence of granulomata (in about 35% to 50% of cases), and a relative lack of depletion of goblet cells on histology. Crohn disease can affect the upper gastrointestinal tract including the small bowel, so a more extensive gastrointestinal workup is often necessary in cases of diagnostic uncertainty.
Indeterminate colitis
SIGNS / SYMPTOMS
In the 5% to 23% of patients with inflammatory bowel disease involving only the colon, Crohn disease cannot be distinguished from UC and a diagnosis of indeterminate colitis is made.[43]
Indeterminate colitis evolves in most patients to a definite diagnosis of UC or Crohn disease on follow-up.
INVESTIGATIONS
Endoscopy and biopsy.
Serologic markers may help.
Radiation colitis
SIGNS / SYMPTOMS
Patients have a history of receiving radiation therapy.
INVESTIGATIONS
Endoscopy and biopsy; histologic findings support this diagnosis.
Infectious colitis
SIGNS / SYMPTOMS
History of recent exposure or travel.
Usually self-limited.
INVESTIGATIONS
Stool culture/biopsy. Occasionally endoscopy findings are helpful to exclude infectious causes for colitis.[24]
Diverticulitis
SIGNS / SYMPTOMS
Older age, fever, nausea, diarrhea, or constipation.
INVESTIGATIONS
Leukocytosis, CT scan.
CT scan can demonstrate evidence of colitis which is distinguishable from diverticulitis.[24]
Sigmoidoscopy and barium studies contraindicated in acute diverticulitis due to risk of perforation.
Irritable bowel syndrome
SIGNS / SYMPTOMS
Lower abdominal pain and bloating associated with alteration of bowel habits. Abdominal discomfort relieved with defecation.
INVESTIGATIONS
Patients have an absence of abnormal laboratory tests, and normal levels of inflammatory markers.
Endoscopy and biopsies are normal.
Mesenteric ischemia/ischemic colitis
SIGNS / SYMPTOMS
Older age, history of cardiovascular disease.[24]
INVESTIGATIONS
Computed tomography scan/endoscopy. Typical finding is thickening of the bowel wall in a segmental pattern.
Endoscopic findings include pale mucosa with petechial bleeding. Bluish hemorrhagic nodules may be seen representing submucosal bleeding; these correspond to "thumbprints" seen on radiographic studies.
Vasculitis
SIGNS / SYMPTOMS
Abdominal pain, bloody stool. Systemic symptoms (fever, malaise, weight loss), vasculitis skin rash.
INVESTIGATIONS
Biopsy shows vasculitis pattern (leukocytoclastic, necrotizing).
Prolonged use of cathartics
SIGNS / SYMPTOMS
History of use.
INVESTIGATIONS
Melanosis coli on endoscopy.
Lymphogranuloma venereum
SIGNS / SYMPTOMS
To consider in men who have sex with men.[44]
INVESTIGATIONS
Full sexual health check and specific testing for Chlamydia trachomatis.
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