Which physical exam finding is characteristic of a hydrocele?

• A. Painless, cystic scrotal swelling that transilluminates
• B. Firm, non-tender mass that does not transilluminate
• C. Tender swelling with erythema
• D. Palpable inguinal lymphadenopathy

Answer: (A)

Hydrocele presents as a painless, cystic scrotal swelling due to fluid around the testicle within the tunica vaginalis. On exam, shining a light through the scrotum causes transillumination because the fluid allows light to pass, producing a glow. This transillumination helps distinguish it from solid scrotal masses, which are typically firm and do not transmit light. In contrast, a tender swelling with erythema points to infection or inflammation such as epididymitis or orchitis, and palpable inguinal lymphadenopathy suggests infection or malignancy in the groin area rather than a hydrocele. Therefore, the characteristic exam finding is a painless, cystic scrotal swelling that transilluminates.