A 42-year-old woman with a 10-year history of Crohn disease presents with acute abdominal pain, fever (39.1°C), and diarrhea. She had been non-compliant with her medications for 2 months. On examination, she has rebound tenderness in the left lower quadrant. Upright abdominal X-ray shows pneumoperitoneum. CT abdomen with IV contrast reveals a focal perforation in the terminal ileum with surrounding inflammation, mesenteric fat stranding, and a small localized collection. What is the most appropriate next step in management?

Explanation

## Management of Perforated Crohn Disease with Pneumoperitoneum **Key Point:** In Crohn disease with **free pneumoperitoneum** and **peritonitis** (rebound tenderness), immediate surgical intervention — laparotomy with resection of the perforated segment — is the standard of care, regardless of whether the collection appears localized on CT. ## Critical Imaging and Clinical Findings | Feature | Clinical Significance | |---------|----------------------| | **Pneumoperitoneum on upright X-ray** | Confirms free perforation — surgical emergency | | Rebound tenderness (LLQ) | Peritoneal irritation / peritonitis | | Terminal ileum involvement | Classic site for Crohn disease perforation | | Localized collection on CT | Does NOT override free air + peritonitis | | Mesenteric fat stranding | Transmural inflammation | | Fever 39.1°C | Systemic sepsis response | ## Why Immediate Surgery Is Required The **combination of pneumoperitoneum + peritonitis** is the decisive factor here. While percutaneous drainage is appropriate for **contained abscesses without free air** (e.g., Hinchey Stage I–II diverticulitis or Crohn abscess without perforation), the presence of **free intraperitoneal air** indicates an ongoing, unsealed perforation. In this setting: 1. **Free air = active leak** — the bowel wall defect is not sealed; percutaneous drainage of the small collection does not address the ongoing contamination. 2. **Peritonitis** (rebound tenderness + fever) — indicates established peritoneal contamination requiring surgical source control. 3. **Non-compliance for 2 months** — the bowel is acutely inflamed and friable; medical optimization alone is insufficient when there is active perforation. **High-Yield:** The management algorithm for Crohn perforation: - **Contained abscess, NO free air, NO peritonitis** → Percutaneous drainage + antibiotics → delayed elective surgery - **Free pneumoperitoneum ± peritonitis** → **Immediate laparotomy + resection** (emergency surgery) This patient has **free pneumoperitoneum + peritonitis** → Option D (immediate laparotomy with resection) is correct. ## Why Other Options Are Wrong - **Option A (Percutaneous drainage):** Appropriate only for walled-off abscesses without free perforation. Free air on upright X-ray mandates surgery — drainage does not seal the bowel defect. - **Option B (Antibiotics + observation):** Inadequate for free perforation with peritonitis; delays definitive treatment and risks septic deterioration. - **Option C (Endoscopic closure):** Contraindicated in Crohn disease — transmural inflammation makes endoscopic therapy futile and dangerous. Reserved for iatrogenic perforations in non-inflamed bowel. **Clinical Pearl:** The upright abdominal X-ray finding of pneumoperitoneum is the key discriminator. A CT showing a "localized collection" does not negate the free air — it simply means the peritoneal contamination has not yet spread diffusely. Surgical source control remains mandatory. *(Harrison's Principles of Internal Medicine, 21e, Ch. 295; Sabiston Textbook of Surgery, 21e)*