A 52-year-old man with a known inguinal hernia presents to the emergency department with acute onset severe pain in the groin, vomiting, and abdominal distension. On examination, the hernia is tender, irreducible, and the overlying skin is erythematous. Bowel sounds are absent. Which investigation is most appropriate to confirm strangulation and guide immediate management?

Explanation

## Investigation of Choice for Hernia Strangulation ### Clinical Context This patient presents with the classic triad of strangulated hernia: **pain, vomiting, and irreducibility** with signs of ischemia (erythema, tenderness). Confirmation of strangulation and assessment of bowel viability is critical before emergency surgery. ### Why CT with IV Contrast is Superior **Key Point:** High-resolution CT abdomen/pelvis with IV contrast is the investigation of choice for suspected strangulated hernia because it: 1. **Confirms strangulation** — demonstrates bowel wall enhancement loss, mesenteric edema, and ascites 2. **Assesses bowel viability** — identifies ischemic bowel (target sign, pneumatosis intestinalis) 3. **Identifies complications** — perforation, peritonitis, extent of necrosis 4. **Guides surgical planning** — determines resection margins and extent of surgery 5. **High sensitivity and specificity** — >95% for detecting strangulation ### Comparison with Other Modalities | Investigation | Sensitivity for Strangulation | Utility | Limitation | |---|---|---|---| | **Plain X-ray** | 40–60% | Shows obstruction only; non-specific | Cannot assess viability or ischemia | | **CT with contrast** | >95% | Gold standard; assesses viability & complications | Requires IV access; slight radiation | | **Ultrasound** | 70–80% | Portable; no radiation; good for hernia anatomy | Operator-dependent; limited for bowel ischemia | | **MRI** | 90%+ | Excellent soft tissue; no radiation | Slow; contraindicated if metal; overkill for acute setting | ### Clinical Pearl **High-Yield:** In a clinically strangulated hernia (pain + irreducibility + systemic signs), do NOT delay surgery for imaging. However, **if diagnosis is uncertain**, CT with contrast is the single best test to confirm strangulation and guide resection decisions. Plain films may show obstruction but cannot assess viability — a critical distinction that changes surgical urgency. ### Mnemonic: STRANGULATION IMAGING **S**ensitivity → **CT** (>95%) **T**issue viability → **CT contrast** (shows enhancement loss) **R**apid diagnosis → **CT** (minutes) **A**ssess complications → **CT** (pneumatosis, perforation) **N**o delay needed → **CT** (bedside ultrasound if unstable) [cite:Sabiston Textbook of Surgery 21e Ch 44]