What symptoms did you have that led to the testing that produced these two findings? That is probably just as important as the findings you mentioned in determining whether to worry too much. In your shoes, I would find it somewhat reassuring that they believe you can wait until the 17th for another CAT scan. It must not be something that needs immediate attention at least.
Blood in the urine can occur for numerous reasons including kidney stones and bladder problems/infection, as well as lupus inflammation of the kidneys although usually you would also be leaking protein too. I've never heard of a thickened appendix before, so have no idea what to say about that! If you get acute pain in the lower right side, it could be an infected appendix which will require immediate treatment/surgery.
Good luck - let us know what you find out!