Can a ct scan without contrast show a tumor in your bladder?

It may: But a contrast enhanced study would be more sensitive. If concerned, see a urologist for full evaluation and diagnostic work-up. Best wishes.

Occassionally: A large ulcerating cancer perforating thru muscularis will show up. A small superficial lesion of mucosa can only de defined on cytoscopy. This is the type of lesion that after biopsy can be treated by intra bladder bcg.