Intrarenal Artery Resistive Index – An Invaluable Tool In Detecting Obstructive Uropathy

Abstract

Background: Ultrasound is more sensitive than being specific in the diagnosis of renal obstruction. Ultrasound provides less details about the pelvicalyceal anatomy and incomplete visualization of the dilated ureter. It cannot provide the functional information; thus, it lacks the specificity of the excretory urography.  In a significant of number of cases ultrasound proves to be less sensitive, where pelvicalyceal system dilatation is absent. This study evaluates the use of intrarenal artery resistive index in detecting obstructive uropathy.

Aim: Comparison of intrarenal arterial doppler RI in obstructed vs non-obstructed ureters and evaluating the diagnostic precision of intrarenal doppler resistive index in ureteric obstruction.

Methodology: This prospective study included 100 patients in the age group of 18 to 70 years, with acute ureteric colic secondary to unilateral ureteric obstruction caused by calculus, that is validated either by grey scale imaging and aliasing in colour doppler or by Intravenous Urography. The intra-renal RI values were recorded in every patient.

Result: RI was higher in obstructed kidneys in all the cases with a Mean RI of > 0.06. The mean peak systolic velocity (PSV) value and the end diastolic velocity (EDV) value were lower in the obstructed kidney as compared to the non-obstructed kidney.

Conclusion: The conventional evaluation of kidneys, ureter and bladder are done using grey scale imaging. In a few instances standard greyscale evaluation falls short, when collecting system dilatation is absent. Hence adding the duplex doppler with RI as marker, to the standard protocol of obstructive uropathy evaluation proves to be a highly sensitive tool for diagnosis.