Role of ultrasound in obstructive uropathy
What is the role of ultrasound in the evaluation of obstructive uropathy?
Ultrasound is the primary modality used for detection and characterization of obstructive uropathy.
Hydronephrosis is the most common finding in unilateral upper urinary tract obstruction involving the ureteropelvic junction or ureter.
In early obstruction (first 1 to 3 days) or in an anuric or dehydrated state, hydronephrosis may be mild or absent in the setting of obstruction.
Duplex Doppler ultrasonography can be used to calculate renal arterial resistive indices, which can improve the sensitivity and specificity in detecting obstruction. In acute obstruction, a resistive index of >0.70 is often indicative of obstruction.
In chronic obstruction, there is often a progressive loss of the echo-rich fat in the plane of Gil Vernet.
Ultrasonography may also identify a distended urinary bladder in the setting of bladder outlet obstruction.