Hi My 90 Year Old Dad Had Catheter Inserted Week

Hi my 90 year old dad had catheter inserted week ago due to retention. he has had some blood come through over past few days and GP referred to A&E, where he spent many hours over two day period, they advised have some blood as on blood thinners, and refer on for other assessments and have left the catheter in for next few weeks. He is now having lots of blood clots coming through past three hours (past history of benign prostate, has had operations and on long term meds), we don't want to take him back to A&E on Fri night at his age but is this something that is serious/urgent re blood loss? What further tests should he have? He is not fit for surgery at his age and very reluctant to go back to A&E as having severe pain in his hip and uncomfortable. Bloods were normal at A&E yesterday.