Blood in the semen can be caused by several things. This can include infections like prostatitis or STDs as well as more serious conditions like prostate cancer. Many times the cause is unexplained.
A reasonable initial test would be a urine test looking for any infection, followed by a transrectal ultrasound to image the prostate for any masses.
These options can be discussed with your personal physician or in conjunction with a urology referral.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
Medical Weblog:
kevinmd_b