Went to er knowing was kidney stones x-ray im fine. since had ultra sound and ct w/cont now have fractured ribs? how can this be? no fall/blow to ribs

See below: Non-contrast CT of the abdomen/pelvis is the best imaging modality to diagnose "stones" within the urinary tract (kidney, ureter, bladder). CT with IV contrast and renal ultrasound best for evaluating renal masses. It would be quite unusual to sustain an acute rib fracture without having pain or a history of some sort of trauma. Certainly, a CT can sometimes identify and report an "old/healed" fx.