Blood in the semen can result from STIs, such as gonorrhea, chlamydia and genital herpes, but there are several additional causes, notes Mayo Clinic. Other potential causes include testicular trauma, hemophilia, prostate cancer, excessive sexual activity and orchitis. Additionally, several medical procedures, including vasectomies, prostate biopsies, brachytherapy and radiation to treat prostate cancer, can also cause blood in the semen. In rare cases, the blood is a symptom of testicular cancer, amyloidosis, tuberculosis, cysts or polyps.
In most cases, there is no identifiable explanation for why a patient has blood in his semen, explains Mayo Clinic. Research indicates that only about 4 percent of men who have had blood in their semen on multiple occasions go on to develop prostate cancer.
In addition to blood in the semen, other symptoms of sexually transmitted infections in men include urinary frequency, painful urination, painful ejaculation, discharge, and sores or bumps in the genital area, states Healthline. Testing is important whenever there is a concern about a possible STI, as many infected men never exhibit any symptoms. Even in the absence of symptoms, an STI can negatively impact a man's or his partner's health. Common methods of testing for STIs include urine tests, blood tests and swab tests of the genital area, explains Mayo Clinic.