Epididymitis is a common infectious disease of the male genital tract, while varicocele is a vascular lesion of the spermatic cord. Both diseases may cause localized painful swelling and discomfort, but there are essential differences. Epididymitis is often caused by bacterial, mycoplasma, chlamydia and other pathogenic microorganisms, and the epididymis can be found locally swollen with tenderness and enlarged by ultrasound. Varicocele is the result of tortuous and dilated veins, and the dilated veins are accompanied by venous blood reflux.