4. Prostate Infection
While an enlarged prostate and resultant blood might be caused by the harmless BPH, it can also be the result of an infection.
Here, an infection affects the prostate and causes it to become enlarged due to swelling. This can also cause other symptoms such as fever, nausea and lethargy.
If you suspect that you have an infected prostate, then you should see a doctor and they might prescribe antibiotics to solve the problem.