What is diverticulitis?

Diverticulitis: Definition, Diagnosis, and Management

Diverticulitis is an inflammatory condition of colonic diverticula (outpouchings of the intestinal wall) that presents with abdominal pain, typically in the left lower quadrant, and may be accompanied by fever, changes in bowel habits, and elevated inflammatory markers. 1

Definition and Epidemiology

• Diverticulitis occurs when diverticula (abnormal outpouchings of the large intestine) become inflamed and/or infected 1
• The annual incidence in the United States is approximately 180 per 100,000 persons, resulting in more than 1.9 million outpatient visits and 208,000 inpatient admissions annually 1
• The financial burden is significant, with annual healthcare costs estimated at $5.5 billion 1
• While traditionally considered a disease of older adults, the incidence in younger adults (40-49 years) increased by 132% from 1980 through 2007 1

Classification

Diverticulitis is categorized into two main types:

1. Uncomplicated Diverticulitis

   • Involves thickening of the colon wall and peri-colonic inflammatory changes 1
   • Represents approximately 88% of diverticulitis cases 1

2. Complicated Diverticulitis

   • Includes the presence of abscess, peritonitis, obstruction, stricture, and/or fistula 1
   • Accounts for about 12% of diverticulitis cases 1
   • Most common complications include phlegmon or abscess, followed by peritonitis, obstruction, stricture, and fistula 1

Clinical Presentation

• The most common presenting symptom is acute or subacute abdominal pain, usually located in the left lower quadrant 1
• Other common symptoms include:
  • Fever 1
  • Changes in bowel habits 1
  • Nausea without vomiting 1
  • Elevated white blood cell count and/or C-reactive protein (CRP) 1

Diagnosis

• Clinical suspicion alone is correct in only 40-65% of patients, highlighting the need for imaging 1
• Computed tomography (CT) scan of the abdomen and pelvis with oral and intravenous contrast is the gold standard diagnostic test with a sensitivity and specificity of approximately 95% 1
• CT findings typically show:
  • Diverticula
  • Thickening of the colon wall
  • Increased density of pericolic fat 1
• Alternative imaging modalities include:
  • Abdominal ultrasonography - less radiation but operator-dependent 1
  • MRI - very sensitive but less specific than CT and generally not used in acute settings 1
• Plain radiographs cannot confirm the diagnosis but may help assess for complications such as perforation or obstruction 1

Management

Management depends on the severity and classification of diverticulitis:

Uncomplicated Diverticulitis

• Most patients with uncomplicated diverticulitis can be managed in an outpatient setting 1
• Antibiotics can be used selectively rather than routinely in immunocompetent patients with mild uncomplicated diverticulitis 1
• For patients requiring antibiotics (those with systemic symptoms, increasing leukocytosis, age >80, pregnancy, immunocompromise, or chronic medical conditions):
  • Oral options: amoxicillin/clavulanic acid or cefalexin with metronidazole 2
  • IV options (for those unable to tolerate oral intake): cefuroxime or ceftriaxone plus metronidazole, or ampicillin/sulbactam 2

Complicated Diverticulitis

• Requires intravenous antibiotics such as ceftriaxone plus metronidazole or piperacillin-tazobactam 2
• May require additional interventions:
  • Percutaneous drainage for abscesses 2
  • Surgical intervention for peritonitis, large abscesses, or other severe complications 2

Prevention of Recurrence

To reduce the risk of recurrence, patients should:

• Consume a high-quality diet 1
• Maintain a normal body mass index 1
• Be physically active 1
• Avoid smoking 1
• Limit use of nonsteroidal anti-inflammatory drugs (except aspirin prescribed for cardiovascular disease prevention) 1

Important Considerations

• The risk of complicated diverticulitis is highest with the first presentation 1
• Approximately 5% of patients may experience smoldering diverticulitis, characterized by persistent abdominal pain and continued evidence of inflammation on CT scan 1
• Elective segmental resection should not be advised based solely on the number of episodes but should be personalized based on disease severity, patient preferences, and risk-benefit assessment 1

Complications

• Approximately 5-10% of patients with diverticulosis develop diverticulitis 1
• Of those with diverticulitis, about 12% will develop complications 1
• Mortality rates differ significantly between elective (0.5%) and emergency (10.6%) colon resection for diverticulitis 2