A 62-year-old woman presents with a small, tender swelling below the inguinal ligament in the medial thigh. On examination, the mass is firm, irreducible, and tender. Clinical examination suggests femoral hernia. Which investigation is most appropriate to confirm the diagnosis and assess for bowel obstruction?

Explanation

## Investigation of Choice for Femoral Hernia Diagnosis ### Why CT with IV Contrast is Optimal **Key Point:** CT scan of the abdomen and pelvis with IV contrast is the gold standard for confirming femoral hernia and assessing for complications (incarceration, strangulation, bowel obstruction). **Clinical Pearl:** Femoral hernias are notoriously difficult to diagnose clinically because they are often small, deep, and easily confused with lymph nodes or other groin masses. Imaging is essential for confirmation. **High-Yield:** CT provides: - Clear visualization of the hernia sac location (below inguinal ligament, medial to femoral vessels) - Assessment of hernia contents (omentum vs. bowel) - Detection of bowel obstruction (transition point, bowel dilatation) - Evaluation of bowel viability (enhancement pattern, wall thickness) - Staging of urgency for surgical intervention ### Diagnostic Accuracy of Imaging Modalities | Investigation | Sensitivity | Specificity | Best For | Limitations | |---|---|---|---|---| | **CT with IV contrast** | 95–100% | 98–100% | Confirmation + complication assessment | Cost, radiation | | **Ultrasound (high-res)** | 70–85% | 80–90% | Initial screening, non-emergency | Operator-dependent, limited in obese patients | | **Plain X-ray (erect)** | <50% | Variable | Only if obstruction suspected | Poor soft-tissue resolution | | **MRI** | 90–95% | 95% | Recurrent/complex hernias | Time, cost, not first-line | ### Why This Patient Needs CT The **tender, irreducible** presentation raises concern for **incarceration or strangulation**. CT with IV contrast is the only investigation that can: 1. Confirm the diagnosis definitively 2. Assess bowel viability (perfusion) 3. Detect early obstruction 4. Guide urgency of surgical repair **Mnemonic: FAST-CT** — Femoral hernia Assessment: Soft-tissue, Contents, Transition (obstruction), Complications. [cite:Sabiston Textbook of Surgery 21e Ch 43]