The nurse is performing an admission assessment for a client with pyelonephritis who has urgency and burning while urinating. Which finding indicates an expected response when the nurse percusses the costovertebral angle?

A. Rebound tenderness is typically associated with peritoneal irritation and is not expected in pyelonephritis. It is more commonly observed in conditions like appendicitis or peritonitis. B. Sharp, severe pain upon percussion of the costovertebral angle (CVA) is a hallmark sign of pyelonephritis, indicating inflammation or infection in the kidneys. This response, known as CVA tenderness, is a key diagnostic indicator of this condition. C. An audible thud without pain would be considered a normal finding and does not suggest the presence of pyelonephritis or other kidney-related issues. The absence of pain would likely rule out significant kidney inflammation. D. Rigidity and firmness are typically associated with muscle guarding or abdominal wall tension rather than kidney involvement. This finding would not be expected in the context of pyelonephritis.