Kidney Imaging and Hydronephrosis Assessment

Renal ultrasound evaluates kidney size echogenicity corticomedullary differentiation and the presence of hydronephrosis and calculi and is often the first line test for suspected obstruction infection or chronic kidney disease. Hydronephrosis grading uses standardized criteria and technologists document the level and severity of dilation and any associated ureteral dilation when visible. Doppler assessment of renal perfusion and resistive indices provides additional information about vascular compromise and about acute versus chronic changes. Bladder scanning for post void residual and assessment of bladder wall thickness complement renal evaluation and support urologic decision making.

Stone Detection and Limitations

Ultrasound can detect many renal and proximal ureteral stones as echogenic foci with posterior acoustic shadowing and Doppler twinkling artifact can increase sensitivity for small calculi. However ultrasound is less sensitive than CT for small distal ureteral stones and for complex stone burden and technologists document limitations and recommend further imaging when clinical suspicion remains high. Hydronephrosis without visible stone prompts evaluation for alternative causes such as extrinsic compression or ureteral stricture and correlation with clinical and laboratory data guides next steps.

Transplant Surveillance and Vascular Assessment

Ultrasound is central to renal transplant surveillance and assesses graft size perfusion resistive indices and perinephric collections and Doppler evaluation of the transplant artery and vein detects stenosis thrombosis or flow abnormalities. Serial measurements and consistent sampling sites support trend analysis and early detection of rejection or vascular complications. Ultrasound guided aspiration of collections and biopsy of the graft require sterile technique and careful planning and documentation of sampling sites and of immediate post procedure imaging supports patient safety and follow up.