A 58-year-old woman with no prior abdominal surgery presents with acute abdominal pain, vomiting, and constipation for 12 hours. On examination, she is afebrile with a soft, distended abdomen. Plain radiograph shows a massively dilated colon with a 'coffee bean' appearance and a transition point at the sigmoid region. CT abdomen confirms a twisted sigmoid colon with a whirled mesentery sign. What is the most likely diagnosis, and what is the next step in management?

Explanation

## Clinical Diagnosis: Sigmoid Volvulus with Endoscopic Management ### Pathophysiology and Epidemiology **Key Point:** Sigmoid volvulus accounts for 5–10% of all intestinal obstructions in developed countries but up to 30% in developing nations (India, Africa). It occurs when the sigmoid colon twists around its mesentery, creating a closed-loop obstruction. ### Classic Imaging Findings **High-Yield:** The **'coffee bean' sign** is pathognomonic for sigmoid volvulus: - Twisted appearance of the dilated sigmoid colon on plain radiograph - The two limbs of the twisted loop appear as a single structure resembling a coffee bean - **Transition point** at the site of twist (usually at the rectosigmoid junction) **Clinical Pearl:** On CT, the **'whirled mesentery' sign** (spiral arrangement of mesenteric vessels and fat around the axis of rotation) is highly specific for volvulus and distinguishes it from other causes of colonic obstruction. ### Imaging Comparison: Sigmoid vs. Cecal Volvulus | Feature | Sigmoid Volvulus | Cecal Volvulus | |---------|------------------|----------------| | **Location** | Sigmoid colon | Cecum ± ascending colon | | **Radiograph sign** | Coffee bean | Bird's beak or comma | | **Mesentery** | Long, redundant | Abnormally mobile | | **Whirled mesentery** | Yes | Yes | | **Age of presentation** | Elderly (60–80 yrs) | Younger (30–50 yrs) | | **Risk factors** | Chronic constipation, neuropsych disease | Pregnancy, adhesions, malrotation | | **Management** | Endoscopic decompression first-line | Surgical (higher recurrence with endoscopy) | ### Management Algorithm for Sigmoid Volvulus ```mermaid flowchart TD A[Sigmoid volvulus diagnosed on imaging]:::outcome --> B{Signs of strangulation?}:::decision B -->|Yes: fever, peritonitis, elevated lactate, pneumatosis| C[Immediate surgery]:::urgent B -->|No: uncomplicated| D[Attempt endoscopic decompression]:::action D --> E{Successful decompression?}:::decision E -->|Yes| F[Place rectal tube, IV fluids, NPO]:::action E -->|No| G[Surgical decompression/resection]:::action F --> H[Elective sigmoid colectomy within 2-4 weeks]:::action G --> I[Definitive treatment]:::outcome ``` ### Why Endoscopic Decompression First? **Key Point:** In uncomplicated sigmoid volvulus (no signs of strangulation), endoscopic decompression is the first-line treatment because: 1. **High success rate** — 60–90% of cases resolve with endoscopy 2. **Lower morbidity** than immediate surgery 3. **Allows time** for elective surgical planning (sigmoid colectomy) after stabilization 4. **Avoids operative risk** in elderly or medically frail patients **Warning:** Endoscopic decompression is contraindicated if there are signs of strangulation (fever, peritonitis, elevated lactate, pneumatosis intestinalis, or perforation on imaging). ### Recurrence and Definitive Management **Clinical Pearl:** Sigmoid volvulus has a **high recurrence rate** (up to 50%) after endoscopic decompression alone. Elective sigmoid colectomy is recommended within 2–4 weeks of successful decompression to prevent recurrence. [cite:Harrison 21e Ch 297; Robbins 10e Ch 17]