How should complicated appendicitis be managed, including the appropriate antibiotic regimen, percutaneous drainage if indicated, and timing of appendectomy?

Management of Complicated Appendicitis

Patients with complicated appendicitis (perforation, abscess, or phlegmon) require urgent source control with appendectomy, broad-spectrum antibiotics covering gram-negative organisms and anaerobes, and postoperative antibiotics for 3-5 days maximum if adequate source control is achieved. 1

Antibiotic Regimen

Initial Therapy

• Start broad-spectrum antibiotics immediately upon diagnosis covering facultative/aerobic gram-negative organisms (especially E. coli) and anaerobes (especially Bacteroides) 1

Acceptable Regimens for Adults:

• Piperacillin-tazobactam (preferred single agent) 1
• Ampicillin-sulbactam 1
• Ticarcillin-clavulanate 1
• Imipenem-cilastatin 1
• Third/fourth-generation cephalosporin + metronidazole 1
• Aminoglycoside + metronidazole 1

Pediatric Regimens:

• Ampicillin + clindamycin (or metronidazole) + gentamicin (most common combination) 1
• Alternatives: ceftriaxone-metronidazole or ticarcillin-clavulanate plus gentamicin 1
• Extended-spectrum antibiotics offer no advantage over narrower-spectrum agents in children 1

Surgical Management

Perforated Appendicitis Without Abscess:

• Proceed with urgent appendectomy (laparoscopic or open based on surgeon expertise) to achieve source control 1, 2
• Both approaches are equally acceptable 1
• Surgery should not be delayed once diagnosis is established 2

Well-Circumscribed Periappendiceal Abscess:

• Manage with percutaneous drainage when feasible 1
• Defer appendectomy in these patients (interval appendectomy approach) 1
• Operative drainage is acceptable if percutaneous drainage is not feasible 1

Phlegmon or Small Non-Drainable Abscess:

• Consider non-operative management with antibiotics alone if patient presents several days after symptom onset 1
• This avoids a potentially more morbid procedure than simple appendectomy 1

Postoperative Antibiotic Duration

Adults:

• Discontinue antibiotics after 24 hours if adequate source control achieved - this is safe and reduces hospital stay 1
• Maximum duration: 3-5 days with adequate source control 1
• Fixed-duration therapy (approximately 4 days) produces similar outcomes to longer courses (8 days) 1
• Do NOT prolong antibiotics beyond 3-5 days with adequate source control 1

Children:

• Switch to oral antibiotics after 48 hours 1
• Total duration less than 7 days 1
• Oral antibiotics are as effective as IV with no difference in abscess rates (11.6% vs 8.1%) or readmissions (14% vs 16.2%) 1

Interval Appendectomy Considerations

• Do NOT perform routine interval appendectomy after non-operative management in young adults (<40 years) and children 1
• Recurrence rates after non-operative treatment: 12-24% 1
• Interval appendectomy only prevents recurrence in 1 of 8 patients, not justifying routine use 1
• Perform interval appendectomy only for recurrent symptoms 1

Exception - Patients ≥40 Years Old:

• Perform colonoscopy and interval full-dose contrast-enhanced CT scan after non-operative management 1
• Incidence of appendiceal neoplasms is high (3-17%) in this age group 1

Critical Pitfalls to Avoid

• Do NOT use prophylactic drains - they increase hospital stay (6.5 vs 4 days), antibiotic duration (5 vs 3.5 days), and analgesic requirements without reducing wound infections (15.9% vs 18.2%) or intra-abdominal abscesses (8% vs 10.7%) 3
• Do NOT continue postoperative antibiotics in uncomplicated appendicitis - single preoperative dose is sufficient 1
• Do NOT delay surgery for perforated appendicitis without abscess - urgent intervention is required 1
• Do NOT attempt prolonged antibiotic therapy alone if an appendicolith is present - this predicts antibiotic failure and warrants surgical management 2