Possible causes of testicular swelling: 1. Acute orchitis. When bacterial infection causes testicular inflammation, testicular congestion and edema can occur, accompanied by obvious pain, especially when the pain is more intense when moving, and can even radiate to the groin area or waist. It is recommended that an ultrasound examination be performed. If the testicular parenchyma is enlarged with increased blood flow, acute orchitis is considered and anti-infection treatment is needed. 2. Testicular torsion, which usually occurs at night, presents acute scrotal pain, and swelling and pain of the testicle can be found by touching it with the hand. This condition belongs to one of the emergency cases and needs to be reset immediately. It is recommended to perform testicular blood flow color Doppler examination, and if the torsion of the spermatic cord is confirmed, emergency surgery is needed for treatment. 3. Occupational lesions of the testis, such as tumors of the testis. In this case, the pain is usually not obvious, but the testicle can be felt to be obviously enlarged, with hard texture, and the feeling of sinking scrotum when walking. In this case, the possibility of testicular cancer should be suspected, and blood tests should be performed to find out whether there is an increase in alpha-fetoprotein and human chorionic gonadotropin, and CT examination of the testicles should be performed to further exclude it.