A 62-year-old man is referred to the outpatient clinic with a painless groin swelling below the inguinal ligament, which he has had for 6 months. It is easily reducible and he is asymptomatic. What is the most appropriate investigation to confirm the diagnosis of femoral hernia?

Explanation

## Investigation of Choice for Uncomplicated Femoral Hernia ### Clinical Presentation The patient has a chronic, asymptomatic, easily reducible groin swelling below the inguinal ligament—classic presentation of an uncomplicated femoral hernia. The investigation must confirm diagnosis with high accuracy while remaining cost-effective and non-invasive. ### Why Ultrasound is Optimal for Stable Cases **Key Point:** Ultrasound is the investigation of choice for uncomplicated femoral hernia because it: - Has high sensitivity (70–85%) and specificity (75–90%) for diagnosis - Directly visualizes the hernia sac, contents, and defect in the femoral canal - Is non-invasive, no radiation, no contrast required - Is cost-effective and widely available - Allows dynamic assessment (reducibility, Valsalva maneuver) - Requires no special preparation **High-Yield:** In stable, asymptomatic patients, ultrasound is the first-line imaging modality. CT is reserved for acute presentations, suspected complications, or when ultrasound is inconclusive. ### Diagnostic Algorithm for Femoral Hernia ```mermaid flowchart TD A[Suspected Femoral Hernia]:::outcome --> B{Acute symptoms?}:::decision B -->|Yes: pain, obstruction, vomiting| C[CT abdomen/pelvis with IV contrast]:::action B -->|No: chronic, asymptomatic, stable| D[Ultrasound groin]:::action C --> E[Assess viability, complications]:::outcome D --> F[Confirm diagnosis, plan elective repair]:::outcome ``` ### Comparison of Imaging Modalities in Stable Femoral Hernia | Feature | Ultrasound | CT | MRI | Doppler US | |---|---|---|---|---| | Sensitivity | 70–85% | >95% | 90–95% | Not applicable | | Cost | Low | High | Very high | Low | | Radiation | None | Yes | None | None | | Contrast needed | No | Yes (IV) | No | No | | Time | 10–15 min | 20–30 min | 30–45 min | 10–15 min | | First-line stable | **Yes** | No | No | No | | Dynamic assessment | Yes | No | No | Yes (for vessels) | **Clinical Pearl:** Ultrasound allows real-time assessment of reducibility and can demonstrate the hernia sac contents (bowel loops, omentum) passing through the femoral canal below the inguinal ligament—pathognomonic for femoral hernia. ### Mnemonic: SAFE Ultrasound for Femoral Hernia - **S** — Simple, non-invasive, no contrast - **A** — Accurate (sensitivity 70–85% in stable cases) - **F** — First-line imaging for uncomplicated hernia - **E** — Economic and easily available **Tip:** Perform ultrasound with patient standing and during Valsalva maneuver to maximize hernia visibility and confirm reducibility—this dynamic assessment is unique to ultrasound and aids in surgical planning.