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By Michael C. DiMarino, MD, Division of Gastroenterology and Hepatology, Department of Medicine, Thomas Jefferson University

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Diverticulitis is inflammation of a diverticulum, which can result in phlegmon of the bowel wall, peritonitis, perforation, fistula, or abscess. The primary symptom is abdominal pain. Diagnosis is by CT. Treatment is with bowel rest, antibiotics (ciprofloxacin, or a 3rd-generation cephalosporin plus metronidazole), and occasionally surgery.

Diverticulitis occurs when a micro or macro perforation develops in a diverticulum, releasing intestinal bacteria. The resultant inflammation remains localized in about 75% of patients. The remaining 25% may develop abscess, free intraperitoneal perforation, bowel obstruction, or fistulas. The most common fistulas involve the bladder but may also involve the small bowel, uterus, vagina, abdominal wall, or even the thigh.

Diverticulitis is most serious in elderly patients, especially those taking prednisone or other drugs that increase the risk of infection. Nearly all serious diverticulitis occurs in the sigmoid.

Symptoms and Signs

Diverticulitis usually manifests with pain or tenderness in the left lower quadrant of the abdomen and fever. Peritoneal signs (eg, rebound or guarding) may be present, particularly with abscess or free perforation. Fistulas may manifest as pneumaturia, feculent vaginal discharge, or a cutaneous or myofascial infection of the abdominal wall, perineum, or upper leg. Patients with bowel obstruction have nausea, vomiting, and abdominal distention. Bleeding is uncommon.


  • Abdominal CT

  • Colonoscopy after resolution

Clinical suspicion is high in patients with known diverticulosis. However, because other disorders (eg, appendicitis, colon or ovarian cancer) may cause similar symptoms, testing is required. Abdominal CT with oral and IV contrast is preferred, although findings in about 10% of patients cannot be distinguished from colon cancer. Colonoscopy, after resolution of the acute infection, is necessary for definitive diagnosis.


  • Varies with severity

  • Liquid diet, oral antibiotics for mild disease

  • IV antibiotics, npo for more severe disease

  • CT-guided percutaneous drainage of abscess

  • Sometimes surgery

A patient who is not very ill is treated at home with rest, a liquid diet, and oral antibiotics (eg, ciprofloxacin 500 mg bid amoxicillin/clavulanate 500 mg tid plus metronidazole 500 mg qid). Symptoms usually subside rapidly. Some recent data suggest some patients may recover from mild, acute, uncomplicated diverticulitis without antibiotic therapy. The patient gradually advances to a soft low-fiber diet for 4 to 6 wk. The colon should be evaluated after 6 to 8 wk with a colonoscopy or barium enema. After 1 mo, a high-fiber diet is resumed.

Patients with more severe symptoms (eg, pain, fever, marked leukocytosis) should be hospitalized, as should patients taking prednisone (who are at higher risk of perforation and general peritonitis). Treatment is bed rest, npo, IV fluids, and IV antibiotics (eg, ceftazidime 1 g IV q 8 h plus metronidazole 500 mg IV q 6 to 8 h).

About 80% of patients can be treated successfully without surgery. An abscess may respond to percutaneous drainage (CT guided). If response is satisfactory, the patient remains hospitalized until symptoms are relieved and a soft diet is resumed. A colonoscopy or barium enema is done 4 wk after symptoms have resolved.


Surgery is required immediately for patients with free perforation or general peritonitis and for patients with severe symptoms that do not respond to nonsurgical treatment within 48 h. Increasing pain, tenderness, and fever are other signs that surgery is needed. Surgery should also be considered in patients with any of the following: 3 previous attacks of mild diverticulitis (or one attack in a patient < 50); a persistent tender mass; clinical, endoscopic, or x-ray signs suggestive of cancer; and dysuria or pneumaturia associated with diverticulitis in men (or in women who have had a hysterectomy) because this symptom may presage fistula formation or perforation into the bladder.

The involved section of the colon is resected. The ends can be reanastomosed immediately in healthy patients without perforation, abscess, or significant inflammation. Other patients have a temporary colostomy with anastomosis carried out in a subsequent operation after inflammation resolves and their general condition improves.

Key Points

  • Diverticulosis is the presence of multiple diverticula in the colon; diverticulitis is inflammation of a diverticulum.

  • Diverticulitis occurs when a diverticulum perforates, releasing intestinal bacteria.

  • Inflammation remains localized in about 75% of patients; the remainder develop abscesses, free intraperitoneal perforation, bowel obstruction, or fistulas.

  • Diagnose using abdominal CT with oral and IV contrast; do colonoscopy 6 to 8 wk after resolution to make definitive diagnosis.

  • Management depends on severity but typically includes antibiotics and sometimes percutaneous or surgical drainage.

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