An 18-yr-old man comes to the emergency department because he has had left scrotal pain for several hours. He says the pain is accompanied by nausea and began suddenly while he was shoveling snow. He continued shoveling, and the pain and nausea suddenly disappeared after a few minutes. Toward the end of shoveling, the pain and nausea returned and his scrotum started to swell, so he decided to seek medical care.