The role of ultrasound in the management of patients with occult groin hernias

INTRODUCTION: Groin ultrasound scanning is commonly used to examine patients with obscure groin pain or swelling. A recent study has shown ultrasound has a poor positive predictive value (PPV) in diagnosing groin hernias although earlier studies reported PPV values as high as 100%. Our aims were to calculate ultrasound's accuracy in diagnosing occult groin hernias in symptomatic patients and assess how management of these patients is affected by ultrasound result. METHODS: We retrospectively analysed 375 symptomatic adult patients, who between February 2008 and March 2010, had ultrasound to diagnose groin hernias when clinical examination was inconclusive. Patients were identified on a prospective radiology database and all groin ultrasounds were performed by either one consultant radiologist or one radiographer. RESULTS: Ultrasound was positive in 199 patients, of which 118 underwent surgery. Using operative findings as the gold standard, ultrasound's PPV for groin hernias was 70% (95% CI: 62-78%). Ultrasound was equivocal in 42 patients of which hernias were diagnosed in 7 of the 10 who had surgery. Ultrasound was negative in 151 patients of which none were later diagnosed with hernias during 3 years' median follow-up. CONCLUSION: Ultrasound is poor in diagnosing occult groin hernias with a PPV of 70% suggesting a 30% chance of negative groin exploration. The equivocal ultrasound group requires careful follow-up as a considerable number were later diagnosed with hernia. The absence of subsequent hernia diagnosis in the negative ultrasound group suggests it may be a useful rule-out test to exclude occult groin hernias in symptomatic patients.