Many think of it as 'sticking.' implantation in humans always occurs when the embryo is between 6-7 days old. A very popular concept on the internet now in 2012, 'implantation bleeding, ' is speculative and mostly not useful.
Also, urinary stones can form in the bladder lining due to an accumulation of debris and chemicals. Broken blood vessels can cause blood in the urine, often because of torn or enlarged veins on the inner surface of the prostate. Blood in the urine also can be caused by the sudden stretching of the bladder wall.
Most of the time, blood in the semen is caused by swelling or infection of the prostate or seminal vesicles. The problem may occur after a prostate biopsy. Blood in the semen may also be caused by: 1  Blockage due to enlarged prostate (prostate problems) 2  Infection of the prostate.  Irritation in the urethra (urethritis)