The bleeding from a vein close to the external opening of the urethra (the hole where the urine comes out when urinating) after masturbating might have been caused by excessive friction during the masturbation and/or increased blood supply during the erection. While the latter is normal and cannot be prevented, you might want to use lubricants in the future if you experience bleeding again.


The bleeding itself is not a problem if it lasts for several minutes and only a small amount of blood is lost.


Otherwise, you are advised to visit a urologist for a physical examination.