What is the management of perforated appendicitis with abscess?

Management of Perforated Appendicitis with Abscess

Non-operative management with intravenous antibiotics and percutaneous drainage (when available) is the recommended first-line treatment for perforated appendicitis with periappendiceal abscess, as this approach results in fewer complications and shorter hospitalization compared to immediate appendectomy. 1, 2

Initial Diagnostic Approach

• Obtain CT imaging to confirm the diagnosis and distinguish between phlegmon (inflammatory mass) versus abscess (fluid collection), as this distinction directly influences treatment decisions 1, 2
• CT findings determine whether percutaneous drainage is technically feasible based on abscess size, location, and accessibility 1, 2

First-Line Treatment Strategy

Non-Operative Management (Preferred Initial Approach)

For periappendiceal abscesses, initiate broad-spectrum intravenous antibiotics combined with percutaneous image-guided drainage when interventional radiology is available. 1, 2

• This conservative approach is associated with significantly fewer complications including wound infections, intra-abdominal abscesses, ileus, and bowel obstruction compared to immediate appendectomy 1
• Success rate for non-operative management ranges from 70-90% for larger collections 1
• Percutaneous drainage combined with antibiotics results in 92% success rate without surgery and significantly reduces hospital stay by approximately 6.4 days compared to antibiotics alone 3, 4

Antibiotic Selection

Administer broad-spectrum antibiotics covering gram-negative organisms and anaerobes:

• Piperacillin-tazobactam is FDA-approved for appendicitis complicated by rupture or abscess in adults and pediatric patients ≥2 months 5
  • Adult dosing: 3.375g IV every 6 hours for 7-10 days 5
• Meropenem is FDA-approved for complicated intra-abdominal infections including complicated appendicitis 6
  • Adult dosing: 1g IV every 8 hours 6
• For critically ill patients with healthcare-associated infections, consider meropenem 1g every 8 hours or other carbapenems 1

Percutaneous Drainage Technique

• Drainage is most beneficial for abscesses ≥3 cm in diameter, as antibiotics alone have high failure rates for larger collections 4
• CT-guided drainage has higher success rates (82.7%) compared to ultrasound-guided drainage (64.3%) 7
• Lower abscess grade and transgluteal approach when anatomically feasible are associated with higher complete resolution rates (90.9%) 7
• Approximately 58% of abscesses require percutaneous drainage; many resolve with antibiotics alone 3

Small Collections (<3 cm)

• Trial of antibiotics alone is appropriate for collections <3 cm, with consideration for needle aspiration if persistent to guide antibiotic coverage 1, 2

When Immediate Surgery is Indicated

Proceed directly to appendectomy when:

• Percutaneous drainage is not available or not technically feasible 1, 2
• Hemodynamic instability or septic shock is present 1
• Clinical signs of diffuse peritonitis develop 1
• Patient fails to improve within 48-72 hours of conservative management 3
• Approximately 25% of patients with appendiceal abscess fail percutaneous drainage and require operative intervention 1

Surgical Approach When Required

• Laparoscopic appendectomy is the preferred approach when advanced laparoscopic expertise is available, with low threshold for conversion 1, 2
• Laparoscopic surgery for appendiceal abscess results in 90% uneventful recovery versus 50% with conservative treatment, with fewer readmissions (3% vs 27%) and fewer additional interventions (7% vs 30%) 1
• Both open and laparoscopic approaches are viable options 1
• Routine intra-operative irrigation does not prevent abscess formation and may be avoided 1

Interval Appendectomy Considerations

Routine interval appendectomy is NOT recommended after successful non-operative treatment. 1, 2

• Recurrence rate after successful non-operative management is 12-20% 1
• Perform interval appendectomy only for patients who develop recurrent symptoms 1, 2
• Among patients treated conservatively, 80% are cured without surgery 1
• Interval appendectomy carries 12.4% morbidity and additional costs to prevent recurrence in only 1 of 8 patients 1

Critical Exception for Older Adults

For patients ≥40 years old treated non-operatively, perform both colonoscopy and interval full-dose contrast-enhanced CT scan due to 3-17% incidence of appendicular neoplasms in this age group 1, 2

Predictors of Treatment Success

Patients most likely to succeed with non-operative management:

• Presence of phlegmon rather than abscess on CT imaging (100% success vs 57% with abscess requiring drainage) 8
• Hemodynamic stability 1
• Absence of diffuse peritonitis 1
• Lower abscess grade 7

Risk factors for percutaneous drainage failure:

• Need for abscess drainage increases failure rate to 43% 8
• Patient complexity and female gender 1
• Earlier drainage timing 1

Common Pitfalls to Avoid

• Do not perform immediate appendectomy for perforated appendicitis with well-formed abscess when interventional radiology is available, as this increases morbidity 1, 9
• Ensure complete appendiceal resection during surgery if operative approach is chosen; incomplete resection can lead to stump appendicitis requiring reoperation 9
• Do not rely on antibiotics alone for abscesses ≥3 cm, as failure rate is unacceptably high without drainage 4
• Monitor patients closely for 48-72 hours after initiating conservative management to identify early treatment failures 3