A 28-year-old woman presents with a 48-hour history of right lower quadrant pain, fever (39.1°C), and vomiting. On examination, she has severe tenderness and rigidity in the RLQ with rebound tenderness. Her WBC is 15,200/µL. Abdominal ultrasound shows a dilated, non-compressible appendix (10 mm) with a thick wall, surrounding free fluid, and a small loculated collection (3 cm) adjacent to the appendix. What is the most appropriate management?

Explanation

## Diagnosis: Perforated Appendicitis with Localized Abscess **Key Point:** This patient has complicated acute appendicitis with perforation and abscess formation. The clinical signs (severe peritonitis, fever, leukocytosis) and imaging findings (thick-walled appendix, loculated collection) indicate a surgical emergency requiring immediate intervention. **High-Yield:** A localized abscess (3 cm) in the setting of acute peritonitis is NOT amenable to percutaneous drainage alone — it requires surgical drainage and appendicectomy to prevent recurrence and sepsis. ## Management Algorithm for Complicated Appendicitis ```mermaid flowchart TD A[Perforated appendicitis with abscess]:::outcome --> B{Abscess size?}:::decision B -->|< 3 cm + stable| C[Antibiotics + percutaneous drainage if accessible]:::action B -->|> 3 cm OR peritonitis| D[Immediate surgery]:::urgent D --> E{Hemodynamically stable?}:::decision E -->|Yes| F[Open appendicectomy + drainage]:::action E -->|No| G[Resuscitate, then surgery]:::urgent F --> H[Definitive treatment in acute phase]:::outcome C --> I[Interval appendicectomy at 6-8 weeks]:::action ``` ## Comparison: Acute vs. Interval Appendicectomy in Complicated Cases | Scenario | Management | Rationale | |----------|-----------|----------| | **Perforated + large abscess (>3 cm) + peritonitis** | Immediate open appendicectomy + drainage | Acute phase surgery is safer; delays risk sepsis and recurrence | | **Perforated + small abscess (<3 cm) + stable** | Percutaneous drainage + antibiotics → interval appendicectomy | Allows inflammation to settle; reduces operative morbidity | | **Uncomplicated acute appendicitis** | Laparoscopic appendicectomy | Standard care; lower morbidity | | **Appendiceal mass (>6 weeks duration)** | Conservative management → interval appendicectomy | Inflammation well-organized; acute surgery high-risk | **Clinical Pearl:** The presence of peritonitis (severe tenderness, rigidity, rebound) indicates that the infection is not well-localized and requires urgent surgical drainage. Percutaneous drainage alone will not control the sepsis. **Mnemonic:** **PADS** = Perforated Appendicitis with Drainage Surgery - **P**erforated appendicitis - **A**cute peritonitis (peritoneal signs present) - **D**rainage (surgical, not percutaneous) - **S**urgery (open appendicectomy in acute phase) ## Why NOT the Other Options - **Laparoscopic appendicectomy:** Contraindicated in the presence of peritonitis and large abscess. The peritoneal contamination and need for adequate drainage favor open surgery. Laparoscopy has higher conversion rates in complicated cases. - **Percutaneous drainage + interval appendicectomy:** This approach is reserved for well-localized, small abscesses (<3 cm) in hemodynamically stable patients WITHOUT peritoneal signs. This patient has severe peritonitis, making acute surgical intervention necessary. - **Conservative antibiotics alone:** Without drainage of the abscess and removal of the appendix, the patient risks sepsis, recurrent infection, and fecal fistula formation. Antibiotics cannot sterilize an abscess without drainage.