Scrotal ultrasound is the first-line imaging modality for evaluating hydrocele because it provides a non-invasive, accurate assessment of the scrotal contents. It differentiates hydrocele from other scrotal pathologies such as testicular tumors, epididymal cysts, or hernias, which can present with similar clinical features. Ultrasound can also assess the size, extent, and nature (simple or complex) of the fluid collection, guiding appropriate management. This imaging technique is essential before any surgical intervention to rule out underlying testicular pathology. Thus, scrotal ultrasound is indispensable in the clinical algorithm for hydrocele evaluation.

Reference: Campbell-Walsh Urology, 12th Edition.