For the diagnosis of pyelonephritis, it is first necessary to confirm the diagnosis. Generally, patients should first undergo routine urine tests. In these tests, the presence of white blood cells and positive nitrites, along with clinical symptoms such as back pain, blood in urine, and fever are common. A routine blood test often shows elevated white blood cells and C-reactive protein. These indicators together suggest the presence of pyelonephritis. Furthermore, a culture of a clean-catch midstream urine sample can be done. If the bacteria grow to a certain quantity, it can also help in confirming the diagnosis of pyelonephritis. Additionally, to assess complications associated with pyelonephritis, it is necessary to perform blood tests for kidney function and an ultrasound of the urinary system to rule out conditions such as acute renal failure, renal papillary necrosis, and perinephric abscess, among others.