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Gastroenterology - Diverticulitis - Fast Facts | NEJM Resident 360

Diverticulosis refers to the presence of colonic diverticula or saclike pouches of colonic mucosa and submucosa that herniate through the muscle layer, covered only by serosa.

Acute diverticulitis is an inflammatory condition that usually involves the sigmoid colon. Diverticulosis refers to asymptomatic diverticula in the walls of the digestive tract. Clinically, patients with diverticulitis present with fever, abdominal pain, and left-lower-quadrant pain. Risk factors for developing diverticulitis include smoking, physical inactivity, and obesity, and low dietary fiber intake.

Colonoscopic View of Normal-Appearing Colonic Mucosa and Two Diverticula

Colonoscopic view of an incipient diverticulum (panel A) and two diverticula associated with a blood vessel (panel B).
(Source: Diverticulitis. N Engl J Med 2018.)

Diagnosis

Computed tomography (CT) is used to confirm diagnosis of acute diverticulitis. Specific features on abdominal CT include:

• thickening of the colon wall

• pericolonic fat stranding

• abscesses

• localized air bubbles outside of the bowel lumen

• free air or fluid in the colon wall as demonstrated in the CT below (arrow represents extraluminal air bubble)

CT Image of the Colon in a Patient with Diverticulitis

Panel B shows Hinchey stage I diverticulitis, with a small pericolic abscess and a bubble of extraluminal air (arrow).
(Source: Diverticulitis. N Engl J Med 2018.)

Treatment

First-line therapy for uncomplicated diverticulitis is administration of antibiotics that provide coverage of enteric gram-negative and anaerobic organisms. The most common combination of antibiotics is ciprofloxacin and metronidazole. Both antibiotics have high oral bioavailability and can be prescribed orally in outpatients or stable inpatients. Intravenous antibiotics are required to treat complications such as abscess, perforation, and fistula. Commonly used regimens for treatment of diverticulitis are described in the following table:

(Source: Diverticulitis. N Engl J Med 2007.)

Current guidelines state that antibiotics should be used selectively rather than routinely in immunocompetent patients with mild uncomplicated acute diverticulitis. Antibiotic therapy should be used in patients with uncomplicated diverticulitis who have comorbidities, are frail, who present with refractory symptoms or vomiting, who have a white blood cell count >15,000 mm³ or C-reactive protein >140 mg/L. 

Additional treatment considerations:

• Interventional radiology–guided or surgical drainage may be required for diverticular abscesses.

• Urgent surgery may be warranted in patients who present with sepsis or peritonitis if there is no improvement with antibiotics, medical treatment, and percutaneous drainage.

• Colonoscopy is recommended in appropriate candidates after resolution of acute diverticulitis to exclude the misdiagnosis of a colonic neoplasm.

• Elective surgery can be considered in patients with frequently recurring or smoldering episodes of diverticulitis. 

Patients should be educated on how to reduce the risk of recurrence by:

• losing weight to achieve normal body mass index

• participating in physical activity

• not smoking

• avoiding regular use of NSAIDs (except for aspirin prescribed for secondary prevention of cardiovascular disease)

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