A 42-year-old woman from Delhi presents with acute-onset severe colicky abdominal pain, vomiting, and abdominal distension for 6 hours. She has no prior surgical history. On examination, she is in distress with a rigid, tender abdomen and absent bowel sounds. Plain abdominal X-ray shows multiple dilated small bowel loops with a 'coffee bean' sign. CT abdomen with IV contrast shows twisted mesentery at the transition point, collapsed distal bowel, and mesenteric edema. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Small Bowel Volvulus ### Key Imaging Features **High-Yield:** The **'coffee bean' sign** on plain X-ray and **'whirl sign'** (twisted mesentery) on CT are pathognomonic for small bowel volvulus [cite:Harrison 21e Ch 297]. ### Radiological Findings Diagnostic of Volvulus | Finding | Imaging Modality | Significance | |---------|------------------|-------------| | **Coffee bean sign** | Plain X-ray | Twisted, kinked small bowel loops | | **Whirl sign** | CT | Twisted mesentery around central axis | | **Bird's beak** | CT | Abrupt transition with tapered narrowing | | **Mesenteric edema** | CT | Venous congestion and ischemia | | **Collapsed distal bowel** | CT | Distal segment empty due to obstruction | ### Pathophysiology of Volvulus 1. **Predisposing factors:** - Congenital long mesentery (most common in India) - Adhesions (less common without prior surgery) - Malrotation of midgut - Pregnancy (rare) 2. **Mechanism:** - Bowel twists around mesenteric axis (usually clockwise) - Venous drainage obstructed → edema → arterial compromise - Risk of strangulation and perforation 3. **Clinical urgency:** - Volvulus is a **surgical emergency** (unlike adhesions) - Ischemia develops within 6–8 hours - Mortality ~30% if perforated **Clinical Pearl:** Volvulus typically presents more acutely and severely than adhesion — the patient is often in shock with a rigid abdomen, suggesting strangulation. ### Distinction from Adhesive Obstruction | Feature | Adhesion | Volvulus | |---------|----------|----------| | **Prior surgery** | Almost always | Not required | | **Onset** | Gradual (hours to days) | Acute (minutes to hours) | | **Severity** | Often partial, tolerable | Complete, severe | | **Coffee bean sign** | Absent | Present | | **Whirl sign on CT** | Absent | Present | | **Mesenteric twist** | Absent | Prominent | | **Management** | Conservative first | Immediate surgery | ### Imaging Algorithm for Volvulus ```mermaid flowchart TD A[Acute small bowel obstruction]:::outcome --> B{Plain X-ray findings?}:::decision B -->|Coffee bean sign| C[Suspect volvulus]:::urgent B -->|Dilated loops, no coffee bean| D[Likely adhesion or other cause]:::action C --> E[Urgent CT abdomen]:::action E --> F{Whirl sign present?}:::decision F -->|Yes| G[Confirmed volvulus]:::urgent F -->|No| H[Alternative diagnosis]:::outcome G --> I[Immediate surgical consultation]:::urgent I --> J[Operative detorsion ± resection]:::action J --> K[Outcome depends on viability]:::outcome ``` **High-Yield:** Unlike adhesions, volvulus **cannot be managed conservatively** — it requires emergent surgical detorsion and resection of any necrotic bowel. Delay increases mortality.