One can get blood in their semen. Usually this is obviously
bloodyBloody or tarry stools. Old blood, however, can have an increasingly dark to rusty color. The cause of what is known as “hemospermia” or “hematospermia” is not clear, but this is usually self-limited (clears up on it’s own) and is of no significance.
In your case, I wonder if you had had a previous episode of hemospermia without realizing it and now you have seen some of the old blood ejaculated. Pain is usually not a feature of this problem and probably was unrelated to the semen.
The workup for hemospermia usually consists of a good urologic physical exam and urinalysis. If nothing is found to be abnormal, nothing more needs to done. If you were experiencing a lot of uregency and frequency of urination, I might consider a sperm culture to look for an infection in your case As far as the pain is concerned, if that recurs it will need further evaluation.
S.A.Liroff, M.D.