Enlarged Kidney on CT scan means....??

My wife has been experiencing pain in her right side, went in to her primary care, who sent her to the hospital for a CT scan. The raidologist said her right kidney was enlarged, and that could mean either kidney infection or tumors! They sent her back to the doctor's office for urinalysis, which showed "dirty" urine, which I guess means kidney infection. They sent a urine sample for culturing, so the specific bacteria could be identified. We're waiting for those results, but shouldn't more tests be done to make sure that there are no tumors present in her kidnays? It seems way too important to assume that this is "only" an infection, which can be damaging enough. She's currently taking Macrobid for the infection.