What is the diagnostic utility of ultrasound?
• Estimating kidney size
• Assessing the echogenicity of the kidney (increased echogenicity may indicate chronic kidney disease but is nonspecific)
• Preferred screening modality for suspected obstruction because it is very sensitive to dilatation of the collecting system, such as from obstruction in kidney failure, pelvic neoplasm, in kidney transplant, and in acute urinary tract infection with pyonephrosis
• Complete ureteral obstruction can be excluded by documenting the presence of a ureteral jet (color flow seen on Doppler ultrasound as urine passes into the bladder from the ureteral orifice)
• Can detect kidney calculi as echogenic foci with shadowing
• Can differentiate solid from cystic mass
• Diagnosing adult polycystic kidney disease and screening involved families
• Guiding interventional procedures such as kidney biopsy and cyst aspiration
• Detecting perinephric fluid collections
• Evaluating kidney transplant allograft
