The possible reasons for blood clots in semen are due to symptoms of seminal vesiculitis, urethral trauma or prostate cancer. You should go to the hospital as soon as these symptoms appear. 1. Spermatitis is the main cause due to retrograde infection. Symptoms include pain in the perineum, as well as urge to urinate, frequent urination, painful urination, or pain in the penis during ejaculation. At the same time, when ejaculating, you will find that the semen is red or pink in color. At this time, the treatment usually includes bed rest and taking some antibiotics such as ciprofloxacin. 2. Prostate cancer usually does not show symptoms in the early stage, but when the mass increases in size and thus blocks the urethra, it will cause symptoms such as frequent urination, urgency, and interruption of the urinary line. Treatment includes radical prostatectomy, androgen removal treatment, etc. 3. Urethral trauma can also lead to blood in the semen. Urethral trauma, especially anterior urethral trauma, can lead to urethral bleeding, bloody semen, as well as painful urination, local hematoma and other symptoms. If the bleeding is severe enough to cause shock, the perineum should be immediately compressed to stop the bleeding, and anti-shock treatment should be given, and a catheter should be inserted to drain the urethra for about 2 weeks if necessary. If the urethra is broken, end-to-end anastomosis of the urethra is required. If there is semen with blood clots, you should immediately go to the hospital for treatment, under the guidance of the doctor to comply with medical advice, standardized treatment.