The blood in urine after sex is considered to be related to rough sex, urethral trauma, prostatitis, seminal vesiculitis and other diseases. 1. Rough sex: For some men who are too rough during sex, blood in the urine after sex may occur due to the rupture of capillaries in the genital area. 2. Urethral injury: urethral injury is related to open trauma, closed trauma, medical trauma, etc. Typical symptoms of patients include bleeding in the urethra, pain in the lower abdomen, difficulty in urination, and swelling in the genital area. Therefore, men who have sex after urethral injury may have blood in the urine. 3. Prostatitis: Prostatitis is mainly related to pathogen infection, while irregular sex life, sedentary, etc. are the triggers. Common symptoms include fever, weakness, suprapubic pain, burning sensation in the urethra, and premature ejaculation. Some patients can also be due to pathogenic bacteria to stimulate the local mucous membrane and the phenomenon of blood in the urine after sex. 4. Vesiculitis: Vesiculitis can also cause blood in the urine after sex in some men, but also easily accompanied by perineal distension, ejaculatory pain, urinary frequency, urinary urgency, bloody semen and other symptoms. Vesiculitis is mainly related to infectious factors, and excessive sex, perineal injury is the trigger. 5. Other diseases: If the patient himself exists ureteral stones, cystitis, kidney cancer and other diseases, can also cause blood in the urine after sex. It is recommended that men who have blood in the urine after sex should consult a doctor for examination and treatment after clarifying the cause of the disease.