Clinically, carnal hematuria is classified into initial hematuria, terminal hematuria and complete hematuria according to the time of appearance of the hematuria during urination. Initial hematuria is often indicative of a lesion or site of bleeding, located in the prostate and urethra. Initial hematuria is the appearance of blood at the beginning of urination when the urine stream appears, followed by a rapid change to normal yellow urine. The common causes are as follows: 1. Prostate diseases: including bleeding caused by benign prostatic hyperplasia and prostate cancer, etc.; 2. Urethral lesions: such as urethral inflammation, urethral injury, urethral calculi, etc.