CT Uralscan

I had never heard of a CT uralscan until last Friday, a couple days ago. My husband is scheduled for one on Thursday. That is because he has been passing blood clots. This is nothing to mess with and means some sort of serious condition. However, it go so bad this morning that he had a lot of back pain and lower abdominal pain and 2 blood clots. Once the clots were out he felt so much better. He has been passing clots for about 2 weeks but only 1 the first week and then last week they began to come every day until yesterday, it was every time he went to the bathroom. I talked to the hospital and they said to come to ER. However, now the blood clots have stopped, his back is better and we wonder if he was passing kidney stones or a kidney stone.