A 55-year-old woman with a history of chronic constipation presents with acute abdominal pain, marked abdominal distension, and absence of bowel movements for 3 days. She is afebrile with stable vital signs. Plain abdominal radiograph shows a massively dilated sigmoid colon with a transition point where the sigmoid twists, creating a characteristic "coffee bean" appearance. The small bowel is not dilated. What is the most likely diagnosis and the most appropriate initial management?

Explanation

## Diagnosis: Sigmoid Volvulus with Conservative Initial Management ### Radiographic Diagnosis **Key Point:** The "coffee bean" sign is pathognomonic for sigmoid volvulus. This appearance results from the twisted sigmoid colon creating a characteristic narrowing at the point of torsion, with massive dilatation of the proximal sigmoid. ### Pathophysiology of Sigmoid Volvulus 1. The sigmoid colon twists on its mesentery (usually 180–360 degrees) 2. Most common in elderly patients with chronic constipation and a redundant, elongated sigmoid colon 3. Causes closed-loop obstruction with risk of ischemia and perforation if untreated 4. The "bird's beak" sign marks the transition point where the bowel narrows ### Management Algorithm ```mermaid flowchart TD A["Sigmoid volvulus diagnosed"]:::outcome --> B{"Signs of perforation<br/>or peritonitis?"}:::decision B -->|"Yes"| C["Emergency surgical detorsion<br/>and sigmoidectomy"]:::urgent B -->|"No"| D["Stable patient?<br/>No signs of strangulation?"]:::decision D -->|"Yes"| E["Rigid sigmoidoscopy or<br/>colonoscopic decompression"]:::action D -->|"No"| C E --> F{"Successful<br/>decompression?"}:::decision F -->|"Yes"| G["Elective sigmoidectomy<br/>within 24-48 hrs"]:::action F -->|"No"| C C --> H["Resection of necrotic bowel<br/>if necessary"]:::action ``` ### Key Management Principles | Scenario | Management | |----------|------------| | **Stable, no peritonitis, no perforation** | Rigid sigmoidoscopy or colonoscopy for decompression (success rate 60–90%) | | **Failed endoscopic decompression** | Surgical detorsion and sigmoidectomy | | **Signs of perforation, peritonitis, or strangulation** | Emergency surgery (detorsion ± resection) | | **Recurrent volvulus after successful decompression** | Elective sigmoidectomy within 24–48 hours | **High-Yield:** In a **stable patient without peritonitis**, endoscopic decompression is the first-line treatment. Surgery is reserved for failed endoscopy, perforation, or strangulation. **Clinical Pearl:** Rigid sigmoidoscopy has a lower perforation risk than colonoscopy in sigmoid volvulus and is the preferred initial approach in many centers. However, colonoscopy is also acceptable and may be more readily available. **Warning:** Do NOT proceed directly to surgery in a stable patient — attempt endoscopic decompression first. This allows time for patient optimization and reduces operative morbidity. [cite:Sabiston Textbook of Surgery 21e Ch 46]