What is the management and optimal timing for surgical intervention in a case of perforated appendicitis with abscess?

Management of Perforated Appendicitis with Abscess

For patients with perforated appendicitis with abscess, percutaneous image-guided drainage combined with antibiotics is the recommended first-line treatment when interventional radiology is available; when percutaneous drainage is not available, surgical intervention is indicated. 1

Initial Management Approach

Diagnosis and Assessment

• Use a step-up approach for diagnosis, starting with clinical and laboratory examination, followed by imaging examination (typically CT scan) to confirm the presence and extent of periappendiceal abscess 1
• CT scan findings help distinguish between phlegmon (inflammatory mass) and abscess (fluid collection), which influences management decisions 1

Non-operative Management (First-line approach)

• Non-operative management with antibiotics and percutaneous drainage is recommended as the initial approach for periappendiceal abscess when interventional radiology is available 1
• This approach is associated with fewer complications and shorter overall hospitalization compared to immediate surgery 1, 2
• Percutaneous drainage is particularly indicated for larger abscesses, with reported efficacy ranging from 70% to 90% 1, 3
• CT-guided drainage shows higher success rates (82.7%) compared to ultrasound-guided drainage (64.3%) 3

Antibiotic Therapy

• Broad-spectrum antibiotics should be initiated promptly 4
• For intra-abdominal infections including perforated appendicitis with abscess, piperacillin-tazobactam is FDA-approved and effective against common pathogens including E. coli and Bacteroides fragilis group 4
• A single preoperative dose of broad-spectrum antibiotics is recommended if proceeding to surgery 1
• For complicated appendicitis, postoperative antibiotics are indicated, especially if complete source control has not been achieved 1

When to Operate

Immediate Surgical Intervention

• Surgery is indicated when percutaneous drainage is not available or feasible 1
• Patients who fail to improve with non-operative management (antibiotics ± drainage) within 48-72 hours should undergo appendectomy 2, 5
• Clinical deterioration, hemodynamic instability, or signs of diffuse peritonitis warrant immediate surgical intervention 1

Factors Predicting Failure of Non-operative Management

• Need for abscess drainage increases the failure rate of non-operative management (43% failure rate among patients requiring drainage) 5
• Patients with phlegmon on CT scan are more likely to respond to non-operative management than those with discrete abscesses 5
• Higher abscess grade on imaging is associated with lower success rates of percutaneous drainage 3

Interval Appendectomy

• Routine interval appendectomy is not necessary following successful non-operative treatment of complicated appendicitis 1
• Interval appendectomy should be performed for patients who develop recurrent symptoms 1
• The recurrence rate after non-operative management ranges from 6.5% to 12% 2, 6
• For patients ≥40 years old, both colonoscopy and interval full-dose contrast-enhanced CT scan are recommended after non-operative treatment due to higher incidence (3-17%) of appendicular neoplasms 1

Surgical Approach When Indicated

• Both open and laparoscopic appendectomies are viable approaches for surgical treatment 1
• Laparoscopic approach is suggested as the treatment of choice for patients with complicated appendicitis with phlegmon or abscess when advanced laparoscopic expertise is available 1
• Routine use of intra-operative irrigation during appendectomies does not prevent intra-abdominal abscess formation and may be avoided 1

Common Pitfalls and Caveats

• Failure to recognize when non-operative management is failing can lead to increased morbidity 5
• Delaying surgery when percutaneous drainage is not available may worsen outcomes 1
• Not considering interval appendectomy in patients with recurrent symptoms can lead to repeated episodes of appendicitis 1
• Overlooking the possibility of underlying malignancy in older patients (≥40 years) treated non-operatively 1
• Inadequate source control with percutaneous drainage alone may necessitate surgical intervention 5