The left testicle is a little swollen and painful, there are three common causes: 1, testicular epididymitis: physical examination can be palpated testicular pain, ultrasound suggests rich blood flow, can be diagnosed as epididymitis; 2, prostatitis: physical examination palpation testicle no obvious abnormalities, ultrasound also does not see abnormal, prostate fluid test abnormal, suggests prostatitis; 3, left spermatic varicose vein: physical examination can be palpated earthworm thickened spermatic cord, perform ultrasound examination The disease usually causes infertility, so patients also need to perform routine semen examination, if there are abnormalities, it is recommended to perform surgical treatment. If the testicular swelling and discomfort is obvious, surgery can also be performed, but the rate of pain relief after surgery is debatable.