Urethral pus caused by: 1, sexually transmitted diseases, the most common disease is gonorrhea, is unclean sexual contact and lead to gonococcal infection of the urethra due to the urethra, can appear urethral discharge a large amount of purulent secretion, yellow color, accompanied by urethral itching, tingling, or urinary frequency, urinary urgency and other symptoms; 2, nongonococcal urethritis is because of unclean sexual contact, infection of mycoplasma and chlamydia caused by the urethra will appear Yellow or white thin pus, accompanied by urethral itching, urethral burning or with urinary frequency, urinary urgency, urinary pain and other symptoms, also belongs to the sexually transmitted diseases, through the unclean sexual contact and infection caused by; 3, the presence of urethral diverticula or tumors can cause urethral pus, urethral diverticula suggests that the urethra has a defect, urine is easy to remain in the diverticulum caused by the infection, the urethra will appear. The urethra will be pus-filled.