Blood in the semen can indicate an infection or inflammation according to WebMD. It can also indicate trauma or occur as a result of a medical procedure.
Blood in the semen should be checked by a doctor. If it is caused by an infection, it should be treated by a medical professional. The infection can occur in the glands, the prostate, or other parts of the body that are used in the production or movement of semen. Infection can be caused by different things include sexually transmitted diseases. Inflammation can also be caused by sexually transmitted diseases or other types of infection.