A 52-year-old man presents with a 6-month history of a painless swelling in the right groin that increases on standing and straining. On examination, a soft, compressible mass is palpable above and medial to the pubic tubercle, which reduces on lying down. The diagnosis of inguinal hernia is clinically suspected. Which investigation is most appropriate to confirm the diagnosis and assess the contents of the hernia?

Explanation

## Investigation of Choice for Inguinal Hernia Diagnosis **Key Point:** Ultrasound is the first-line imaging modality for suspected inguinal hernia due to its high sensitivity, specificity, availability, and lack of radiation. ### Why Ultrasound is Optimal **High-Yield:** Ultrasound with dynamic imaging (Valsalva maneuver, standing position) can: - Visualize the hernia sac and its contents (bowel, omentum, fat) - Demonstrate intermittent herniation during straining - Differentiate between direct and indirect inguinal hernia - Assess for bilateral hernias - Evaluate the size and reducibility of the hernia **Clinical Pearl:** The Valsalva maneuver during ultrasound increases intra-abdominal pressure, making an intermittent hernia more apparent. This dynamic assessment is crucial for diagnosis, especially in cases where the hernia may not be clinically apparent at rest. ### Comparison of Imaging Modalities | Investigation | Sensitivity | Specificity | Radiation | Cost | Dynamic Assessment | Clinical Use | |---|---|---|---|---|---|---| | **Ultrasound** | 95–99% | 95–98% | None | Low | Yes (Valsalva) | **First-line** | | CT abdomen/pelvis | High | High | Yes | High | Limited | Reserved cases | | MRI pelvis | High | High | None | Very high | Yes | Research/complex | | Plain radiograph | Low | Low | Yes | Low | No | Not useful | **Warning:** Clinical diagnosis alone is often sufficient for straightforward cases, but imaging is recommended when: - Diagnosis is uncertain - Bilateral hernias are suspected - Recurrent hernia is being evaluated - Preoperative planning is needed ### Role of Other Modalities **CT and MRI** are reserved for: - Evaluation of complicated hernias (incarceration, strangulation) - Assessment of hernia contents in complex cases - Preoperative planning for recurrent or complex hernias - When ultrasound is inconclusive **Plain radiography** has no role in hernia diagnosis unless assessing for bowel obstruction complications.