A 38-year-old woman with a femoral hernia presents with acute lower abdominal pain and vomiting for 6 hours. On examination, the femoral bulge is tender and irreducible. Plain abdominal X-ray shows dilated small bowel loops with air-fluid levels. What is the most appropriate next investigation to confirm strangulation before proceeding to emergency surgery?

Explanation

## Investigation of Choice for Femoral Hernia Strangulation ### Clinical Presentation This patient has **clinical obstruction** (dilated bowel on plain film) with a **tender, irreducible femoral hernia**. The next critical step is to **confirm strangulation** (ischemia) rather than simple obstruction, as this determines urgency and surgical extent. ### Why CT with IV Contrast is the Best Next Step **Key Point:** CT abdomen/pelvis with IV contrast is the single best investigation to: 1. **Confirm strangulation** — demonstrates bowel wall enhancement loss, mesenteric edema, and ischemic changes 2. **Assess viability** — identifies necrotic vs. viable bowel (critical for resection decisions) 3. **Identify complications** — pneumatosis intestinalis, perforation, ascites 4. **Rapid diagnosis** — completed in <5 minutes; does not delay emergency surgery 5. **High accuracy** — sensitivity >95% for strangulation vs. simple obstruction ### Differentiation: Obstruction vs. Strangulation on Imaging | Feature | Simple Obstruction | Strangulation | |---|---|---| | **Plain X-ray** | Dilated bowel, air-fluid levels | Same (non-specific) | | **CT: Bowel wall** | Normal enhancement | Loss of enhancement (ischemia) | | **CT: Mesentery** | Normal | Edema, fat stranding | | **CT: Ascites** | Absent or minimal | Present (peritoneal irritation) | | **CT: Pneumatosis** | Absent | Present (indicates necrosis) | ### Clinical Pearl **High-Yield:** Plain X-ray confirms **obstruction** but cannot distinguish **simple obstruction from strangulation**. CT with contrast is essential because: - **Simple obstruction** → conservative management (NG tube, fluids, observation) - **Strangulation** → emergency surgery (risk of perforation, peritonitis, sepsis) Femoral hernias have a **40% risk of strangulation** (higher than inguinal), making imaging confirmation critical before deciding on urgent vs. semi-urgent surgery. ### Mnemonic: CT CONFIRMS STRANGULATION **C**ontrast enhancement loss → ischemia **T**issue viability assessment → guides resection **C**omplications detected → pneumatosis, perforation **O**bstruction vs. strangulation → differentiates urgency **N**o delay to surgery → rapid imaging **F**emoral hernia high-risk → 40% strangulation rate **I**schemic bowel changes → mesenteric edema **R**apid diagnosis → <5 minutes **M**anagement guided → resection extent **S**ensitivity >95% → gold standard [cite:Sabiston Textbook of Surgery 21e Ch 44; Bailey & Love's Short Practice of Surgery 27e Ch 32]