Which Diagnostic Test Is Most Appropriate to Confirm the Diagnosis of Acute Pyelonephritis in This Patient

Ms. Santos, a 45-year-old Female, Presents to the Emergency Department with Complaints of Fever, Chills and Flank Pain. She Reports Dysuria and Increased Urinary Frequency. on Physical Examination, She Has Costovertebral Angle Tenderness and Is Febrile