Semen consists of sperm and fluids released by the prostate and other glands. The fluids, also called ejaculate, join the sperm as they pass through a series of tubes to the urethra for ejaculation. A number of things can break blood vessels along this route or along the urinary route to the urethra. Broken vessels then leak blood into the semen, urine or both...consult nearest urologist they will do the needful.