Diverticulitis

Diverticulosis refers to the asymptomatic 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 diverticula of the sigmoid colon.

Risk factors:

• genetic factors

• smoking

• physical inactivity

• obesity

• low dietary fiber intake

Presentation: Clinically, patients with diverticulitis present with fever, abdominal pain, and left-lower-quadrant pain. Other signs include nausea, change in bowel habits, and an elevated leukocyte count and C-reactive protein (CRP) level.

Classification: Diverticulitis is classified as uncomplicated or complicated:

• Uncomplicated diverticulitis is associated with the thickening of the colonic wall and pericolonic inflammatory changes.

  • Among patients with uncomplicated diverticulitis, about 5% progress to complicated diverticulitis.

• Complicated diverticulitis includes the changes described above and the presence of abscess, peritonitis, obstruction, stricture, and/or fistulae.

(Source: Diverticulitis. N Engl J Med 2018.)

Diagnosis: Computed tomography (CT) of the abdomen and pelvis (with oral and intravenous contrast) 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)

(Source: Diverticulitis. N Engl J Med 2018.)

Treatment

Diet and pain management: A clear liquid diet can ease symptoms of acute uncomplicated diverticulitis. Diet should be advanced to a low-fiber diet as tolerated. Acetaminophen and antispasmodics can be used for pain.

Antibiotics:

• Antibiotics should be used selectively in patients with mild, uncomplicated diverticulitis with any of the following characteristics:

  • frail patients or patients with comorbidities and uncomplicated diverticulitis

  • immunocompromised state

  • refractory symptoms

  • elevated CRP level (>140 mg/liter) or baseline leukocyte count >15 X 10⁹ cells/liter

  • fluid collection or long segment of inflammation on CT

• Prescribe broad-spectrum antibiotics that provide gram-positive and gram-negative coverage.

  • Ciprofloxacin plus metronidazole is the most common combination of antibiotics. 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.

Additional treatment considerations:

• Interventional radiology can be used for guided or surgical drainage of diverticular abscesses.

• Urgent surgery should be considered in patients who present with sepsis or peritonitis and do not improve with antibiotics, medical treatment, and percutaneous drainage.

• Elective surgical resection can be considered in patients with frequently recurring or smoldering episodes of diverticulitis and in those who are chronically immunosuppressed. The decision should consider the presence of comorbidities, severity of diverticulitis episodes, patient preferences, and surgical risk.

Preventing recurrence: Patients should be educated on how to reduce the risk of recurrent diverticulitis with the following practices:

• Consume a high-quality diet that is rich in fruits, vegetables, legumes, and whole grains and low in red meat and sweets.

• Lose weight to achieve normal body mass index.

• Participate in physical activity.

• Do not smoke.

• Avoid regular use of nonsteroidal anti-inflammatory drugs (NSAIDs [except for aspirin prescribed for secondary prevention of cardiovascular disease]).

Colonoscopy: As malignancy can be misdiagnosed as diverticulitis, an elective colonoscopy is recommended after an episode of complicated diverticulitis or after the first episode of uncomplicated diverticulitis. This can be deferred if a high-quality colonoscopy has been performed in the year before the diverticulitis episode.