What is diverticulitis and how is it managed in adults over 40 years old?

What is Diverticulitis and How is it Managed in Adults Over 40?

Diverticulitis is an inflammatory condition resulting from microscopic or macroscopic perforation of colonic diverticula (outpouchings of the intestinal wall), most commonly affecting the sigmoid colon in Western populations, and requires CT imaging for diagnosis with management ranging from observation alone in uncomplicated cases to antibiotics and surgery in complicated presentations. 1

Definition and Epidemiology

Diverticulitis develops when diverticula become inflamed due to focal necrosis and perforation, distinct from diverticulosis which is simply the presence of these outpouchings. 1 The annual incidence in the United States is approximately 180 per 100,000 persons, resulting in over 200,000 hospital admissions annually with healthcare costs exceeding $5.5-6.3 billion per year. 2, 3

Key epidemiologic facts:

• Only 1-4% of patients with diverticulosis will develop acute diverticulitis in their lifetime 3
• Prevalence increases dramatically with age: <10% in those under 40 years, rising to 50-66% in those over 80 years 4, 5
• Approximately 85-88% of diverticulitis cases are uncomplicated 2, 3
• The incidence in younger adults (40-49 years) increased by 132% from 1980 through 2007 2

Clinical Presentation

The hallmark symptom is acute or subacute left lower quadrant abdominal pain, often accompanied by fever, altered bowel habits, nausea, and laboratory evidence of inflammation. 2, 3 However, clinical diagnosis alone is unreliable—in elderly patients specifically, positive and negative predictive values of clinical diagnosis were only 0.65 and 0.98 respectively, compared to >0.95 and 0.99 with cross-sectional imaging. 1

Critical point: In elderly and immunocompromised patients, presentation may be atypical with milder symptoms despite severe underlying disease, necessitating a lower threshold for imaging. 6

Diagnostic Approach

CT scan of the abdomen and pelvis with IV contrast is the gold standard diagnostic test and should be performed in all patients with suspected diverticulitis to confirm diagnosis and distinguish uncomplicated from complicated disease. 1, 2, 3 CT has sensitivity of 98-99% and specificity of 99-100%. 2, 3

Typical CT findings include:

• Thickening of the colon wall 2
• Increased density of pericolic fat 2
• Presence or absence of complications (abscess, perforation, fistula) 1

Alternative imaging when IV contrast is contraindicated:

• MRI has sensitivity of 0.98 and specificity of 0.70-0.78, but is rarely feasible in urgent settings 1
• Ultrasound can be used, particularly in premenopausal women and young patients to reduce radiation exposure, showing thickened wall >4mm, non-compressibility, and loss of peristalsis 1, 7
• Unenhanced CT showed good sensitivity (98.6%) for detecting diverticulitis but significantly lower sensitivity (61%) for complications 1

Do not rely on clinical examination and laboratory tests alone—imaging is mandatory for accurate diagnosis and treatment planning. 1

Classification

Diverticulitis is classified as either uncomplicated or complicated:

Uncomplicated diverticulitis (85-88% of cases): 2, 3

• Thickening of colon wall and pericolic inflammatory changes only
• May include minimal pericolic air bubbles or small amounts of pericolic fluid (WSES stage 0-1a)

Complicated diverticulitis (12-15% of cases): 2

• Abscess formation (localized or distant)
• Perforation (localized or generalized)
• Fistula formation
• Stricture or obstruction

Management of Uncomplicated Diverticulitis

For immunocompetent patients with uncomplicated diverticulitis without signs of sepsis, antibiotics can be avoided—observation with pain management (acetaminophen) and clear liquid diet is appropriate first-line therapy. 1, 2, 3

This recommendation is based on high-quality evidence from two major randomized trials:

• The AVOD trial (623 patients, mean age 57) showed antibiotic treatment neither accelerated recovery nor prevented complications or recurrence 1
• The DIABOLO trial (528 patients) confirmed observational treatment without antibiotics did not prolong recovery 1

When antibiotics ARE indicated in uncomplicated diverticulitis: 3

• Persistent fever or chills
• Increasing leukocytosis
• Age >80 years
• Pregnancy
• Immunocompromised status (chemotherapy, high-dose steroids, organ transplant)
• Chronic medical conditions (cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes)
• Localized complicated disease with pericolic air or fluid (WSES stage 1a) 1

First-line oral antibiotic regimens: 3

• Amoxicillin/clavulanic acid, OR
• Cefalexin plus metronidazole

For patients unable to tolerate oral intake, IV antibiotics: 3

• Cefuroxime or ceftriaxone plus metronidazole, OR
• Ampicillin/sulbactam

Outpatient management is appropriate for carefully selected patients who: 8

• Are immunocompetent
• Can tolerate oral intake
• Have adequate social support
• Lack severe comorbidities
• Show no signs of severe sepsis

Management of Complicated Diverticulitis

All patients with complicated diverticulitis require broad-spectrum IV antibiotics with gram-negative and anaerobic coverage. 6, 3

Recommended IV antibiotic regimens: 6, 3

• Ceftriaxone plus metronidazole, OR
• Piperacillin-tazobactam

Duration of antibiotic therapy: A short course of 3-5 days after adequate source control is reasonable, with 4-6 days being the typical postoperative duration if source control was adequate. 1 Patients with persistent symptoms after 5-7 days require re-evaluation and further diagnostic investigation. 1

Management by complication type:

Abscess:

• Percutaneous drainage if abscess is large enough (typically >3-4 cm) 8
• IV antibiotics plus drainage often allows conversion from urgent to elective surgery or avoidance of surgery altogether 8

Perforation with purulent or feculent peritonitis:

• Emergent laparotomy with colonic resection 3, 8
• Hartmann's procedure (sigmoidectomy with end colostomy) versus primary anastomosis depends on patient stability, degree of contamination, tissue quality, and comorbidities 8
• Primary anastomosis is preferable in hemodynamically stable, immunocompetent patients without feculent peritonitis, severe edema, ischemic bowel, or malnutrition 8

Fistula or stricture:

• Almost always require segmental colectomy 8

Postoperative mortality:

• Elective colon resection: 0.5% 3
• Emergent colon resection: 10.6% 3

Special Considerations for Elderly Patients (>65 years)

Elderly patients with diverticulitis have unique characteristics that warrant specific management considerations: 1

• More nuanced clinical presentation with potentially milder symptoms despite severe disease 1
• Higher in-hospital and postoperative mortality 1
• Geriatric comorbidities are risk factors for complicated diverticulitis 1
• Lower risk of recurrent episodes compared to younger patients 1
• Lower probability of requiring urgent surgery if recurrence occurs 1

Predictive factors for severe diverticulitis in elderly patients include: 4

• Female sex
• Obesity
• Immunodeficiency
• Advanced age itself

Follow-up and Colonoscopy

Colonoscopy should be performed 6-8 weeks after resolution of acute symptoms in specific circumstances: 6, 8

• All cases of complicated diverticulitis 8
• Atypical clinical presentation 8
• Diagnostic ambiguity 8
• Patients >40-50 years without recent colonoscopy 1, 8
• Rectal bleeding 8

The rationale is to exclude colorectal cancer, Crohn's disease, or alternative diagnoses such as ischemic colitis. 1, 8 The risk of missing underlying malignancy is low but motivates colonoscopy in patients above age 40. 1

Prevention of Recurrence

To reduce recurrence risk, patients should implement the following evidence-based lifestyle modifications: 9, 2

Dietary modifications:

• High-fiber diet from fruits, vegetables, whole grains, and legumes 6, 2
• Avoid red meat and sweets 6
• The myth of avoiding nuts, corn, popcorn, and seeds has been debunked 8

Lifestyle modifications:

• Maintain normal body mass index 9, 2
• Regular physical activity 9, 2
• Smoking cessation (equally or more important than alcohol avoidance) 9
• Avoid NSAIDs except aspirin prescribed for cardiovascular prevention 9, 2

Alcohol consumption:

• Avoid alcoholism, which is a risk factor for incident diverticulitis 9
• Moderate alcohol consumption does not require complete prohibition 9

Elective Surgery Considerations

Elective segmental resection should not be advised based solely on the number of episodes. 2 The decision should be based on:

• Disease severity
• Impact on quality of life
• Patient preferences
• Risk-benefit assessment 2

Surgery appears to improve quality of life in appropriately selected patients. 8 For immunocompromised patients, consultation with a colorectal surgeon regarding elective resection should be considered after recovery due to higher risk of complications. 6

Common Pitfalls to Avoid

• Do not diagnose diverticulitis based on clinical findings alone—CT imaging is mandatory for accurate diagnosis and classification 1
• Do not routinely prescribe antibiotics for all uncomplicated diverticulitis—reserve for patients with specific risk factors 1, 3
• Do not assume elderly patients with mild symptoms have mild disease—they may present atypically with severe underlying pathology 1, 6
• Do not recommend dietary restrictions on nuts, seeds, corn, or popcorn—this outdated advice has been disproven 8
• Do not base surgical decisions solely on number of episodes—individualize based on disease severity and patient factors 2