What does blood in my semen mean?

Q. I've noticed blood streaks in my semen twice over the past 10 days. Is this a sign of something serious?

A. When a man sees blood in his ejaculate, his initial thought is cancer. But the reality is that bloody semen rarely is a sign of cancer.

There are no good statistics on the prevalence of bloody semen, a condition called hematospermia. It probably occurs much more than reported because it tends not to be noticed if a man ejaculates during sexual intercourse.

The most common cause of hematospermia is trauma due to a medical procedure. For instance, more than one-third of men who have a prostate biopsy have blood in their semen for several days. Cystoscopy (catheter insertion through the urethra into the bladder) also can lead to hematospermia, especially if the doctor takes biopsies of the bladder lining.

Other possible causes of bloody semen include an enlarged prostate (benign prostatic hyperplasia, or BPH); injury to the testicles or the prostate, which might result from horseback riding or bicycling; and frequent masturbation. There's no consensus on how soon a man with hematospermia should see his doctor. Most often it goes away on its own. Even when doctors look for a possible cause, typically none is found.

Here is my recommendation. Consult your doctor if the problem continues for more than three weeks. See your doctor sooner if you have additional symptoms, such as fever or pain when you ejaculate or urinate. This might indicate a possible prostate or bladder infection.

— by Howard LeWine, M.D.

Editor in Chief, Harvard Men's Health Watch