What is the recommended management approach for diverticulitis in the UK?

UK Guidance for Diverticulitis Management

Initial Diagnosis and Risk Stratification

For suspected acute diverticulitis, CT scan with oral and intravenous contrast is the gold standard diagnostic test, with 98-99% sensitivity and 99-100% specificity. 1, 2

• Uncomplicated diverticulitis is defined as localized inflammation without abscess, perforation, fistula, obstruction, or bleeding 1, 2
• Complicated diverticulitis involves any of these features: abscess, phlegmon, fistula, obstruction, bleeding, or perforation 1, 2
• Laboratory studies should include complete blood count, C-reactive protein, and basic metabolic panel 1, 2

High-risk features predicting progression to complicated disease include: 1

• CRP >140 mg/L
• White blood cell count >15 × 10⁹ cells/L
• Symptoms lasting >5 days prior to presentation
• Presence of vomiting
• ASA score III or IV
• Presence of fluid collection or longer segment of inflammation on CT

Treatment of Uncomplicated Diverticulitis

Antibiotic Decision Algorithm

In immunocompetent patients with mild uncomplicated diverticulitis without systemic inflammation, antibiotics should NOT be routinely prescribed. 1, 3 The DIABOLO trial with 528 patients demonstrated that antibiotics neither accelerate recovery nor prevent complications or recurrence, with hospital stays actually shorter in the observation group (2 vs 3 days). 1

Reserve antibiotics for patients with ANY of the following criteria: 1, 3, 2

• Immunocompromised status (chemotherapy, high-dose steroids, organ transplant)
• Age >80 years
• Pregnancy
• Persistent fever or chills
• Increasing leukocytosis
• CRP >140 mg/L
• White blood cell count >15 × 10⁹ cells/L
• Presence of vomiting or inability to maintain hydration
• Fluid collection or longer segment of inflammation on CT scan
• Significant comorbidities (cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes)
• Frailty or ASA score III or IV

Antibiotic Regimens When Indicated

Outpatient oral regimens (4-7 days for immunocompetent patients): 1, 3, 2

• First-line: Amoxicillin-clavulanate 875/125 mg orally twice daily, OR
• Alternative: Ciprofloxacin 500 mg orally twice daily PLUS metronidazole 500 mg orally three times daily

Inpatient IV regimens (transition to oral as soon as tolerated): 1, 3, 2

• Ceftriaxone PLUS metronidazole, OR
• Piperacillin-tazobactam

Duration of therapy: 1, 3

• 4-7 days for immunocompetent patients
• 10-14 days for immunocompromised patients

Outpatient vs Inpatient Management

Outpatient management is appropriate when ALL criteria are met: 1, 4

• Able to tolerate oral fluids and medications
• Temperature <38°C (100.4°F)
• Pain score <4/10 (controlled with acetaminophen only)
• No significant comorbidities or frailty
• Not immunocompromised
• Adequate home and social support
• No signs of systemic inflammatory response or sepsis

Hospitalization is required for: 1, 4, 2

• Complicated diverticulitis
• Inability to tolerate oral intake
• Severe pain or systemic symptoms
• Signs of peritonitis or sepsis
• Immunocompromised status
• Significant comorbidities or frailty

Supportive Care

During acute phase: 1

• Clear liquid diet is advised for patient comfort, advancing as symptoms improve
• Pain control with acetaminophen (avoid NSAIDs and opioids when possible)
• Re-evaluation within 7 days is mandatory, earlier if clinical deterioration occurs 1, 4

Treatment of Complicated Diverticulitis

Abscess Management

Small abscesses (<4-5 cm): 1, 5, 4

• IV antibiotics alone for 7 days
• Pooled failure rate of 20%, mortality rate 0.6%

Large abscesses (≥4-5 cm): 1, 5, 4

• Percutaneous CT-guided drainage PLUS IV antibiotics
• Antibiotic duration: 4 days in immunocompetent patients with adequate source control
• Up to 7 days in immunocompromised or critically ill patients

Generalized peritonitis or sepsis: 1, 4, 2

• Emergent surgical consultation
• IV antibiotics (ceftriaxone plus metronidazole OR piperacillin-tazobactam)
• Surgical options: primary resection with anastomosis (preferred in stable patients) or Hartmann's procedure (for critically ill patients)

Post-Acute Management and Prevention

Colonoscopy Timing

Colonoscopy should be performed 4-6 weeks after resolution of acute diverticulitis to exclude malignancy, particularly: 1, 2

• After complicated diverticulitis
• After first episode of uncomplicated diverticulitis in patients >50 years
• When age-appropriate screening is due
• When clinical signs suggest malignancy

Prevention of Recurrence

Lifestyle modifications to reduce recurrence risk: 1, 3

• High-quality diet: High in fiber from fruits, vegetables, whole grains, and legumes (>22.1 g/day); low in red meat and sweets
• Regular vigorous physical activity
• Achieve or maintain normal BMI
• Smoking cessation
• Avoid regular use of NSAIDs and opioids when possible

Important: Do NOT restrict consumption of nuts, corn, popcorn, or small-seeded fruits—these are NOT associated with increased diverticulitis risk. 1, 3

Surgical Considerations

Elective surgery should NOT be based on number of episodes alone. 1 The traditional "two-episode rule" is no longer accepted. 1

Consider elective resection based on: 1, 4

• Quality of life impact (the DIRECT trial showed significantly better quality of life at 6 months with elective sigmoidectomy versus conservative management)
• Frequency of recurrence affecting daily function
• Patient preferences and values
• Operative risks and benefits
• Comorbidities and immune status

Elective resection reduces but does not eliminate recurrence risk: At 5-year follow-up, recurrence rate was 15% with surgery versus 61% with conservative management. 1 However, 22-25% of patients continue to have ongoing abdominal pain after surgery. 1

Immunosuppressed patients should consult with a colorectal surgeon after recovery from acute diverticulitis, as this population is at high risk for complicated recurrence. 1

Common Pitfalls to Avoid

• Do NOT routinely prescribe antibiotics for uncomplicated diverticulitis in immunocompetent patients without risk factors 1, 3
• Do NOT assume all patients require hospitalization—most can be safely managed as outpatients with appropriate follow-up, resulting in 35-83% cost savings 1
• Do NOT unnecessarily restrict nuts, seeds, and popcorn—this is not evidence-based and may reduce overall fiber intake 1, 3
• Do NOT stop antibiotics early if they are indicated, even if symptoms improve 1, 3
• Do NOT apply the "no antibiotics" approach to complicated diverticulitis or Hinchey 1b/2 disease—the evidence specifically excluded these patients 1
• Do NOT delay surgical consultation in patients with frequent recurrences significantly affecting quality of life 1, 4