Colitis

Colitis is inflammation of the lining of the colon. It is a broad term for conditions that cause similar symptoms, including diarrhea, abdominal pain, and sometimes blood in stool. Colitis may be acute or chronic and can occur on its own or as part of other diseases.

Major causes include infectious colitis (bacterial, viral, parasitic), ischemic colitis from reduced blood flow, inflammatory colitis such as ulcerative colitis and Crohn's disease involving the colon, microscopic colitis (collagenous or lymphocytic colitis) characterized by watery diarrhea, radiation colitis after pelvic radiation, and chemical or drug-induced colitis.

Symptoms vary but commonly include diarrhea, cramping or lower abdominal pain, urgency, and sometimes rectal bleeding or mucus. Fever, weight loss, and dehydration may occur in more extensive disease or infection. Diagnosis relies on history, physical examination, stool studies to detect infection, blood tests, and colonoscopy with biopsy; imaging may be used to evaluate complications.

Treatment targets the underlying cause and supportive care. Infectious colitis may require antibiotics or antiparasitics, with fluids and electrolyte management. Inflammatory colitis often uses 5-aminosalicylates, corticosteroids, and may progress to immunomodulators or biologic therapies. Microscopic colitis generally responds to budesonide. Ischemic colitis and radiation colitis are managed based on severity and may require procedures. Some cases need surgery. Prognosis depends on the cause and extent; many forms are controllable, but complications can occur.