How does the doctor know if the diagnosis is hematocele?

Hematocele. Scrotal hematoma.....Blood in scrotum....Is very obvious, the scrotum will be black/blue.....Like an egg plant.....If just swollen it is edema or a hydrocele....
Trauma. Hematocele can usually be diagnosed by history and with ultrasound. Most commonly associated with trauma to scrotum, moderate to severe pain after injury, swelling and bruising. Ultrasound usually shows fluid in layers around testis, and may diagnose testicular injury as well.