The testicular swelling and pain after erection may be caused by: 1. The stagnation of semen due to prolonged erection is caused by receiving sufficient sexual stimulation during the erection process, when the gonads secrete a lot of semen accumulating in the vas deferens testes, and when the state of ejaculation is not reached, the local swelling will be felt. The pain and swelling will be gradually reduced if the ejaculation action is carried out at this time and the semen is completely discharged from the body. When touched by hand, thickened and tortuous blood vessels of the spermatic cord can be felt in the scrotum, accompanied by slight swelling and pain, which can be relieved after ejaculation or after rest.