What Causes Blood In Urine After Having A Stroke?

My father (93 years) has blood in the urine. What can this lead to? He was in the hospital for a light stroke January 16 2015, and it led to 4 days in the hospital and a week in rehab. They gave him lipitor, which we took him off of. Then, tried to thin the blood with Zarelto, but that made him bleed more, ( I believe). They put him on 325 aspirin instead of the zarelto. He is on a heart medication which controls the Atriel Fibulation. The doctor put him on antibiotics, and we go in to take a urine test tomorrow to see if there is an infection. The blood in the urine has been present since about the 21st of January and now it is almost 2 months. I am concerned. What can this lead to?