my friend has been incarcerated for 2.5 yrs now. i have known him for 8 yrs and in this time frame he has, on several occasions, confided in me about blood being in his urine. But it never last for long and is usually forgotten about until the next episode. upon being incarcerated, he is automatically checked for stds and hiv and such and he has always tested negative. in the last week his urine has blood again, he went to medical, they gave him a screen to urinate in and told him to bring back a kidney stone. He woke yesterday and went to urinate. He said he could feel something moving through his system and when it got to the head, it become stuck and he had to work it out. there was more blood and he said what looked like a placenta after a dog gives birth. he takes it to medical and they told him it was tissue. Does this happen often to men, as i have never heard of such. where does tissue come from and what would cause such discomfort.