What is the appropriate treatment for a patient with phlegmon, considering the risk of underlying infection and potential complications?

Treatment of Appendiceal Phlegmon

Non-operative management with antibiotics and percutaneous drainage (if accessible) is the recommended first-line treatment for appendiceal phlegmon in settings without advanced laparoscopic expertise, while laparoscopic appendectomy is the preferred approach when experienced laparoscopic surgeons are available. 1

Initial Treatment Strategy

The choice between operative and non-operative management depends primarily on available surgical expertise and resources:

Non-Operative Management (First-Line in Most Settings)

Non-operative management is a reasonable first-line treatment for appendiceal phlegmon, particularly when advanced laparoscopic expertise is not readily available. 1

• Initiate broad-spectrum intravenous antibiotics covering enteric gram-negative organisms and anaerobes (E. coli and Bacteroides species) 2
• Add percutaneous drainage as an adjunct to antibiotics if the phlegmon is accessible and drainage expertise is available 1
• Percutaneous drainage reduces the rate of recurrent appendicitis, decreases the need for interval appendectomy, and reduces postoperative complications compared to antibiotics alone 1
• Maintain strict clinical monitoring for signs of deterioration or failure to improve 1

Operative Management (When Laparoscopic Expertise Available)

Laparoscopic appendectomy is the treatment of choice for appendiceal phlegmon when advanced laparoscopic expertise is available, with a low threshold for conversion to open surgery. 1, 3

• Early laparoscopic appendectomy is associated with fewer readmissions, fewer additional interventions, and comparable hospital stay compared to conservative treatment 1, 3
• Early appendectomy demonstrates lower rates of bowel resection (3.3% vs 17.1%) compared to initial non-operative management 1, 3, 2
• Expect a 10% risk of bowel resection and 13% risk of incomplete appendectomy during laparoscopic management 1
• Maintain a low threshold for conversion to open surgery (approximately 10% conversion rate) 1

Critical Decision Points

When to Choose Non-Operative Management

• Limited or no advanced laparoscopic expertise available 1
• Patient presents with well-defined phlegmon without diffuse peritonitis 1
• Patient is elderly with significant medical comorbidities and wishes to avoid surgery 1

When to Choose Operative Management

• Advanced laparoscopic expertise is readily available 1, 3
• Patient develops diffuse peritonitis or free perforation (absolute contraindication to non-operative management) 1
• Failure of non-operative management with clinical deterioration 1

Follow-Up and Interval Appendectomy Considerations

Routine interval appendectomy is NOT recommended after successful non-operative management in patients younger than 40 years. 1, 3, 2

• The recurrence rate after successful non-operative treatment is approximately 12-24% 1
• Interval appendectomy carries a non-negligible morbidity rate of 12.4% 1
• Reserve interval appendectomy only for patients who develop recurrent symptoms 1, 4
• The cost-effectiveness analysis shows that interval appendectomy prevents recurrence in only one of eight patients, not justifying routine performance 1

Critical Exception for Older Patients

For patients ≥40 years old treated non-operatively, both colonoscopy and interval full-dose contrast-enhanced CT scan are mandatory due to the high risk of underlying appendiceal neoplasms (3-17%). 3, 2

• The rate of appendiceal neoplasms in patients over 40 years with periappendicular abscess/phlegmon can be as high as 17% 1
• All neoplasms in one major trial were found in patients older than 40 years 1

Special Population Considerations

Elderly Patients

• Non-operative management with percutaneous drainage (if accessible) is suggested for elderly patients with appendicular phlegmon 1
• If percutaneous drainage is unavailable or technically impossible, treat with antibiotic therapy and strict clinical monitoring 1
• Mortality is significantly higher in elderly patients with free perforation and diffuse peritonitis (11.9-15% vs 1.5-2.3%), requiring urgent appendectomy 1

Pediatric Patients

• Meta-analyses show that children with appendiceal phlegmon have better outcomes with non-operative management in terms of complication rates and readmission rates 1
• Non-operative management is associated with lower rates of complications and wound infections 1
• Early appendectomy is associated with reduced length of hospital stay but higher complication rates 1

Common Pitfalls to Avoid

• Do not attempt laparoscopic appendectomy without advanced laparoscopic expertise – this increases the risk of complications including bowel resection 1
• Do not routinely perform interval appendectomy in young patients (<40 years) – this adds unnecessary operative costs and morbidity to prevent recurrence in only one of eight patients 1
• Do not use non-operative management for patients with diffuse peritonitis or free perforation – these patients require urgent appendectomy 1
• Do not fail to screen patients ≥40 years old with colonoscopy after non-operative management – the risk of underlying neoplasm is substantial (3-17%) 1, 3, 2
• Do not continue antibiotics beyond 3-5 days with adequate source control – prolonged antibiotics increase costs and antimicrobial resistance without improving outcomes 2