What is the appropriate management of a peritoneal abscess?

Management of Peritoneal Abscess

For peritoneal abscesses, percutaneous CT-guided drainage combined with broad-spectrum antibiotics is the preferred initial approach in hemodynamically stable patients, while emergency surgical intervention is mandatory for those with diffuse peritonitis, septic shock, or failed percutaneous drainage. 1

Initial Assessment and Risk Stratification

• Obtain urgent contrast-enhanced CT of the abdomen and pelvis to confirm the diagnosis, determine abscess size and location, assess for free air or diffuse peritonitis, and evaluate accessibility for percutaneous drainage. 1
• Assess hemodynamic stability immediately: patients with septic shock (hypotension, oliguria, altered mental status) require emergency surgical source control rather than percutaneous drainage. 1
• Evaluate for signs of diffuse peritonitis including generalized abdominal tenderness, rigidity, and rebound—these patients need urgent laparotomy, not percutaneous drainage. 1

Source Control Strategy

Percutaneous Drainage (Preferred Initial Approach)

• Percutaneous CT-guided drainage is the first-line treatment for well-localized, accessible abscesses in hemodynamically stable patients without diffuse peritonitis, achieving success rates of 74-82% depending on location. 1, 2
• Pelvic abscesses respond best to percutaneous drainage (82% success rate), followed by peritoneal abscesses (74%) and retroperitoneal abscesses (67%). 2
• Multiloculated abscesses or those with fistulous communication have higher failure rates with percutaneous drainage and may require surgical intervention. 2

Surgical Intervention (When Required)

• Emergency laparotomy is mandatory for patients with diffuse peritonitis, septic shock, failed percutaneous drainage after 48-72 hours, or inaccessible abscesses. 1
• Timing is critical: delays in surgical source control beyond 24 hours significantly increase mortality, and operating room latency of 60 hours or longer predicts need for relaparotomy. 1
• Surgical objectives include draining all infected collections, debriding necrotic tissue, controlling the source of contamination (resection or repair of perforated viscus), and placing drains as needed. 1

Special Clinical Scenarios

Small Diverticular Abscesses

• Abscesses less than 3-4 cm in diameter from perforated diverticulitis may be managed with antibiotics alone without drainage in highly selected, hemodynamically stable patients responding to therapy. 1
• Abscesses 4-6 cm typically require percutaneous drainage in addition to antibiotics. 1

Post-Operative Abscesses

• Localized post-operative abscesses without generalized peritonitis can be treated with antibiotics and percutaneous drainage based on clinical condition, abscess size, and interventional radiology availability. 1
• Post-operative peritonitis with diffuse contamination requires prompt surgical re-exploration; delays beyond 24 hours markedly increase mortality. 1, 3

Antimicrobial Therapy

• Initiate broad-spectrum intravenous antibiotics immediately upon diagnosis or strong clinical suspicion of intra-abdominal infection. 1, 4
• For community-acquired infections of mild-to-moderate severity: use ertapenem, cefoxitin, or piperacillin-tazobactam as single agents. 1
• For high-risk or critically ill patients: use carbapenems (meropenem, imipenem-cilastatin, doripenem) or piperacillin-tazobactam at higher doses (4.5g IV every 6 hours). 1, 4
• Duration of antibiotics is 3-5 days (optimally 4 days) after adequate source control; longer courses do not improve outcomes and increase resistance risk. 4, 3
• De-escalate to narrow-spectrum agents within 24-48 hours once culture results and susceptibilities are available. 4

Microbiological Sampling

• Obtain peritoneal fluid or pus for culture (minimum 1-2 mL) and inoculate directly into aerobic and anaerobic transport media before starting antibiotics when feasible. 4
• Blood cultures are not routinely necessary for community-acquired infections but should be obtained in immunocompromised or clinically toxic patients. 1

Monitoring and Follow-Up

• If fever, leukocytosis, or peritonitis signs persist beyond 5-7 days of appropriate therapy, obtain repeat CT imaging to evaluate for residual infection, new abscess formation, or inadequate source control. 4, 3
• Clinical failure of percutaneous drainage (no improvement within 48-72 hours) mandates surgical consultation and likely operative intervention. 2

Critical Pitfalls to Avoid

• Do not delay source control in septic patients: inadequate or late source control is the primary determinant of mortality in peritoneal abscesses. 1
• Do not rely on antibiotics alone for abscesses larger than 4 cm or in patients with signs of systemic sepsis—source control is essential. 1
• Do not extend antibiotic therapy beyond 5 days without clear indication; this promotes resistance without improving outcomes. 4
• Do not perform laparotomy without imaging in hemodynamically stable patients—CT guidance allows for less invasive percutaneous drainage when appropriate. 1, 2
• Do not assume percutaneous drainage will work for multiloculated or fistula-associated abscesses—these typically require surgical intervention. 2