White Matter in Urine

My dad is 77 years old, a diabetic, and is currently under hospice care at home following his third stroke.  He has had a Foley catheter inserted for two weeks.  There has been blood in his urine on and off for several days.  The nurses said that was likely due to his pulling at the catheter tubing.  Starting yesterday there was streaky, white matter floating in his urine.  It did not look like tissue.  The nurses said that they weren't sure what it was.  My dad will not go to the hospital and does not want extensive medical testing.  Our primary concern is my dad's comfort and we are worried that the white substance could be a symptom of something very treatable that could cause him a lot of pain if it's not taken care of, although the hospice team was not concerned.  We'd appreciate any information that you could provide regarding what would cause this symptom.