Hematoma: This is the most likely diagnosis due to the direct trauma to the scrotum, which can cause blood vessels to rupture, leading to blood accumulation and swelling.

Scrotal Contusion: Similar to a hematoma, a contusion can occur from a direct blow to the scrotum, causing bruising and swelling.
Testicular Trauma: Injury to the testicles themselves can cause edema, and it's essential to assess for testicular rupture or other injuries.
Epididymitis: Although less common as an immediate result of trauma, epididymitis (inflammation of the epididymis) can occur, especially if there's an associated infection.

Testicular Rupture: A serious condition that requires immediate surgical intervention. Missing this diagnosis can lead to infertility, infection, or loss of the testicle.
Vascular Injury: Damage to the blood vessels supplying the testicles can lead to ischemia and potentially result in testicular loss if not promptly addressed.
Urethral Injury: Although less directly related to scrotal edema, a urethral injury can occur with severe trauma and is crucial to identify to prevent long-term complications.

Scrotal Cellulitis: An infection of the skin and subcutaneous tissue of the scrotum, which can occur after trauma, especially if the skin is broken.
Orchitis: Inflammation of one or both testicles, usually due to bacterial or viral infection, which can be a rare complication of trauma.
Varicocele: Enlargement of the veins within the scrotum, which can be caused by trauma, although this is less common and might not present immediately after injury.