Can a ct/mri of the pelvis detect bladder cancer i pee a lot and i always have pain on my side and hip bw, rad, urine tests all negative i'm a female?

If your U/A does not: Blood, it is very unlikely you have bladder cancer, but the next logical step is a urologist, cystoscopy and retrograde ureterogram. Ct and mr only after this.

Sometimes: A ct or MRI can detect larger or advanced bladder tumors. However, many bladder tumors are subtle and found on only by looking inside the bladder (cystoscopy). Without blood in your urine on a microscopic evaluation, it is unlikely you have a bladder tumor. Continue to work with your doctor for the right approach and diagnosis. Eventually you may want to see a urologist or urologic gynecologist.

Urine and cystoscopy: Cytology evaluation of urine is a good first screen for bladder cancer. Urine screening is sensitive for high grade tumors but not for low grade tumors. With persistent blood in urine, your urologist may visualize your bladder with a cystoscope (camera) that can detect superficial bladder cancers. Ct/mr may add helpful information, but this is expensive, unnecessary information without screen.