Which assessment finding is most important to report to the health care provider regarding a patient who has had left-sided extracorporeal shock wave lithotripsy?

A. Hematuria: The presence of blood in the urine is expected for the first few days after extracorporeal shock wave lithotripsy. It results from trauma to the urinary tract and usually resolves on its own, so it does not require urgent reporting unless it becomes severe or prolonged. B. Oliguria: Decreased urine output is the most concerning finding because it may indicate obstruction from stone fragments or acute kidney injury. This complication can quickly compromise renal function and requires immediate evaluation by the healthcare provider. C. Ecchymosis in left flank: Bruising around the flank is a common side effect of the shock waves used during lithotripsy. While it may be uncomfortable, it is not considered dangerous and does not require urgent intervention. D. Left flank discomfort: Pain is expected after the procedure due to both the passage of stone fragments and localized tissue trauma. Analgesics are typically used to manage this symptom, and it is not considered a critical finding to report.