Blood in semen

What is the cause of blood  contained in semen?  The Merk Manual indicates that this may be "idiosyncratic" and that it is rare and may be treated with anitbiotics.  Your comments please.

[Kevin Pho, MD]

What you are referring to is known as hematospermia.  The following is taken from UptoDate:

The most common cause of hematospermia is prostate biopsy. Hematospermia lasts more than several days in one-half of men who undergo the procedure.

A variety of conditions other than prostate biopsy have been reported in patients with hematospermia. They include benign and malignant disorders of the prostate gland, seminal vesicles, spermatic cord, and ejaculatory duct system; urogenital infections; metastatic cancers; and vascular disorders. However, it is often impossible to know with certainty whether these conditions are the cause of hematospermia. The cause is idiopathic in a substantial proportion of patients, and the condition frequently resolves spontaneously.

Transrectal ultrasound is the imaging procedure of choice for patients with hematospermia. It can identify structural abnormalities of the prostate gland, seminal vesicles, and spermatic cord, and guide biopsies if any suspicious abnormalities are identified in those organs. Transrectal ultrasound should be obtained as part of the evaluation of hematospermia in men 35 years of age, or when hematospermia persists for more than one month.

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.

Thanks,
Kevin, M.D.

Bibliography:
Weiss et al.  Hematospermia.  UptoDate, 2003.