Bleeding in the urethra when straining may be due to urethral stone, urinary tumor, inflammation and so on. 1. Urethral calculi: If you have urethral calculi, when you stool too hard, you may squeeze the calculi, which may cause damage to the blood vessels of urethral mucosa, and produce the symptom of urethral bleeding. 2. Urological tumor: some malignant tumors of urinary system, such as kidney cancer, bladder cancer, etc., can cause hematuria when the tumor invades into the urinary tract, and can also induce urethral bleeding when straining. 3. Inflammation: such as glomerulonephritis, pyelonephritis, acute cystitis, urethritis and so on. When straining to pass stool, it may increase the local vascular pressure, which may lead to bleeding. In addition to the above factors, there may also be other factors that can cause, it is recommended to go to the hospital in time for the appropriate examination and cooperate with the doctor for treatment.