In a hemodynamically stable patient with complicated sigmoid diverticulitis presenting with a large (10 × 18 × 13 cm) multiloculated intra‑abdominal abscess, sealed perforation, and pneumoperitoneum but no generalized peritonitis, what is the appropriate initial management?

Management of Complicated Sigmoid Diverticulitis with Large Abscess and Sealed Perforation

In a hemodynamically stable patient with a 10 × 18 × 13 cm multiloculated abscess, sealed perforation, and pneumoperitoneum but no diffuse peritonitis, the appropriate initial management is CT-guided percutaneous drainage combined with broad-spectrum intravenous antibiotics, followed by close clinical monitoring for signs of treatment failure. 1

Risk Stratification and Classification

This presentation represents WSES Stage 2a–2b complicated diverticulitis (large abscess with localized perforation), which guides a non-operative first-line approach in hemodynamically stable patients 1. The key distinguishing features that permit conservative management are:

• Hemodynamic stability – absence of hypotension, shock, or tachycardia >100 bpm 1, 2
• Absence of diffuse peritonitis – no generalized abdominal rigidity or rebound tenderness beyond the left lower quadrant 3, 1, 2
• Sealed perforation – the pneumoperitoneum represents contained rather than free perforation 1

Critical caveat: The presence of intraperitoneal free air in a stable patient does not by itself mandate emergency surgery when peritonitis is absent, though this approach carries a 57–60% failure rate and requires intensive monitoring 1, 2.

Initial Management Protocol

1. Immediate Resuscitation and Antibiotic Therapy

• Start broad-spectrum IV antibiotics immediately covering gram-negative and anaerobic organisms 3, 1:

  • Piperacillin-tazobactam 4.5 g IV every 6 hours, OR
  • Ertapenem 1 g IV every 24 hours (preferred if ESBL risk factors present) 1
  • Alternative: Ceftriaxone 2 g IV daily PLUS metronidazole 500 mg IV every 8 hours 3

• IV fluid resuscitation to maintain adequate perfusion 3, 1

2. Percutaneous Drainage

For abscesses ≥4–5 cm (and certainly for a 10 × 18 × 13 cm collection), CT-guided percutaneous drainage is the recommended initial source control method 3, 1. The evidence supporting this approach:

• Abscesses >4 cm have an 18.7% failure rate with antibiotics alone, making drainage essential 1
• Percutaneous drainage achieves success rates comparable to surgery while resulting in lower morbidity 3, 1
• This strategy facilitates subsequent single-stage elective sigmoidectomy rather than emergency Hartmann procedure 3

Technical considerations for multiloculated abscesses:

• Multiple catheters may be required for adequate drainage of all loculations 1
• Obtain drainage fluid for culture to guide antibiotic de-escalation 3, 1

3. Antibiotic Duration After Drainage

• Continue antibiotics for 4 days after successful percutaneous drainage in immunocompetent, non-critically ill patients 3, 1
• Extend to 7 days if the patient is immunocompromised or critically ill 3, 1

Monitoring Protocol for Treatment Failure

Close clinical surveillance is mandatory because non-operative management of this severity of disease has significant failure rates 3, 1, 2. Monitor:

Clinical Parameters (Every 3–6 Hours)

• Vital signs – persistent tachycardia >100 bpm beyond 24 hours despite adequate resuscitation indicates insufficient source control and prompts surgical consultation 1, 2
• Abdominal examination – development of new peritoneal signs (generalized rigidity, rebound tenderness) mandates immediate surgery 1, 2
• Pain assessment – worsening pain score despite drainage suggests treatment failure 1

Laboratory Surveillance (Daily)

• White blood cell count – rising leukocytosis after initial improvement 1, 2
• C-reactive protein – failure to trend downward 1
• Serum lactate – rising levels indicate worsening sepsis 2

Catheter Output

• Monitor drainage volume and character – decreasing output with persistent fever suggests inadequate drainage or new collection 1

Indications for Conversion to Surgery

Proceed to exploratory laparotomy when any of the following occur despite optimal percutaneous management 3, 1, 2:

• Clinical deterioration within 48–72 hours – worsening fever, increasing leukocytosis, or deteriorating abdominal examination 3, 1, 2
• Development of hemodynamic instability – hypotension, shock, or persistent tachycardia 1, 2
• Inability to place drainage catheter or failure of catheter to achieve sepsis control 3, 1
• Persistent symptoms beyond 5–7 days despite adequate drainage and antibiotics – obtain repeat CT to assess for complications 3, 1

Surgical Options When Required

• Hartmann procedure (sigmoid resection with end colostomy) – preferred for hemodynamically unstable patients or those with multiple comorbidities 3
• Primary resection with anastomosis (with or without diverting ileostomy) – may be performed in carefully selected stable patients without significant comorbidities 3

Special Considerations

Contraindications to Colonoscopy

• Colonoscopy is absolutely contraindicated during the acute phase because it can convert a sealed perforation into free perforation 1
• Defer endoscopic evaluation for 4–6 weeks after symptom resolution to exclude underlying malignancy (11% risk in patients with complicated diverticulitis) 1

If Percutaneous Drainage Is Not Feasible

• Antibiotics alone can be attempted with very close clinical monitoring if drainage is technically impossible or unavailable 3
• However, maintain a high index of suspicion for surgical intervention given the large abscess size and sealed perforation 3
• Failure rate with antibiotics alone for large abscesses is 25% 3

Common Pitfalls to Avoid

• Do not proceed to immediate surgery without first attempting percutaneous drainage in a stable patient – this increases morbidity unnecessarily 3, 1
• Do not assume pneumoperitoneum alone mandates surgery – in the absence of diffuse peritonitis, non-operative management is acceptable with close monitoring 1, 2
• Do not delay surgical consultation if the patient shows any signs of clinical deterioration – early involvement improves outcomes 3, 1, 2
• Do not extend antibiotic duration beyond 7 days without reassessment – persistent symptoms should trigger repeat imaging rather than simply longer therapy 3, 1
• Do not attempt colonoscopy during the acute inflammatory phase 1

Expected Outcomes

With appropriate percutaneous drainage and antibiotics:

• Success rate comparable to surgery for source control 3, 1
• Lower morbidity than emergency surgical intervention 3, 1
• Facilitates elective single-stage sigmoidectomy 6–8 weeks later if indicated, avoiding permanent colostomy 3