A 72-year-old woman from Kolkata with a history of diverticulosis presents with acute left lower abdominal pain, fever (39.1°C), and signs of peritonitis. Laboratory studies show WBC 16,000/μL and elevated CRP. CT abdomen with IV contrast reveals free air in the peritoneal cavity, a focal defect in the sigmoid colon wall, and localized purulent collection measuring 4 cm adjacent to the perforation site. What is the most appropriate next step in management based on these imaging findings?

Explanation

## Management of Perforated Diverticulitis with Localized Abscess ### Clinical Scenario Analysis The patient has: - **Acute diverticular perforation** (free air, focal colonic wall defect) - **Localized purulent collection** (4 cm, well-defined) - **Systemic signs of sepsis** (fever, elevated WBC/CRP) - **Peritonitis** (clinical finding) ### Hinchey Classification & Management Algorithm ```mermaid flowchart TD A[Perforated Diverticulitis]:::outcome --> B{Hinchey Stage?}:::decision B -->|Stage I: Microperforation| C[Antibiotics + supportive care]:::action B -->|Stage II: Localized abscess| D{Abscess size?}:::decision D -->|< 4 cm| E[Antibiotics + close monitoring]:::action D -->|≥ 4 cm| F[Percutaneous drainage]:::action F --> G[Interval sigmoidectomy after 6-8 weeks]:::action B -->|Stage III: Purulent peritonitis| H[Emergency surgery with colostomy]:::urgent B -->|Stage IV: Fecal peritonitis| I[Emergency surgery with colostomy]:::urgent C --> J[Elective sigmoidectomy if recurrent]:::action E --> J ``` **Key Point:** The **Hinchey classification** is the gold standard for grading diverticular perforation severity and guides management: | Hinchey Stage | Findings | Management | |---------------|----------|-------------| | I | Microperforation, localized inflammation | Antibiotics, supportive care | | II | Localized abscess (< 4 cm) | Antibiotics ± observation | | II | Localized abscess (≥ 4 cm) | **Percutaneous drainage** + antibiotics | | III | Purulent peritonitis (free pus) | Emergency surgery + colostomy | | IV | Fecal peritonitis (free stool) | Emergency surgery + colostomy | ### Why Percutaneous Drainage? **High-Yield:** In Hinchey Stage II with abscess **≥ 4 cm**, percutaneous drainage (CT or ultrasound-guided) is the standard of care. This: 1. **Controls sepsis** without immediate surgery 2. **Allows inflammation to resolve** (6–8 weeks) 3. **Enables elective single-stage sigmoidectomy** instead of emergency surgery with colostomy 4. **Reduces morbidity** compared to emergency colostomy **Clinical Pearl:** The 4 cm threshold is critical. Abscesses < 4 cm may resolve with antibiotics alone; those ≥ 4 cm require drainage to prevent rupture and generalized peritonitis. ### Imaging Findings in This Case - **Focal colonic wall defect** = perforation site (Hinchey II–IV) - **Free air** = perforation confirmed - **Localized 4 cm collection** = abscess (Hinchey II) - **No diffuse peritoneal contamination** = not Stage III/IV ### Interval Sigmoidectomy After successful drainage and resolution of acute inflammation (typically 6–8 weeks), **elective sigmoidectomy** is performed to prevent recurrence. This avoids emergency colostomy and allows primary anastomosis.