Prostate-specific antigen, abbreviated PSA, is synthesized and secreted into the seminal fluid mainly by prostate epithelial cells and is one of the main components of seminal plasma. The PSA can be elevated in prostate diseases such as prostate hyperplasia, prostatitis, ischemic infarction of the prostate and prostate cancer. The normal tissue barrier between the follicles and ducts of the prostate and the blood circulation system is present. This will lead to a significant increase in the serum PSA level and an increase in the index during the examination.