What can cause renal enlargement in ultrasound findings?

Renal enlargement on ultrasound can be attributed to several conditions that lead to swelling of the kidney tissue. Hydronephrosis, a condition characterized by the accumulation of urine in the renal pelvis due to obstruction, is a common cause of renal enlargement. When urine builds up, it puts pressure on the kidney, causing it to expand. Acute kidney injury, which involves a rapid decline in kidney function, can also lead to swelling as the kidneys react to the inflammatory processes or fluid retention associated with the condition. Additionally, renal tumors can cause localized or generalized enlargement of the kidney due to their mass effect or associated edema. All these factors contribute to the increase in kidney size as observed on an ultrasound.