DIAGNOSTIC ACCURACY OF INTRARENAL RESISTIVE INDEX TO DIFFERENTIATE ACUTE OBSTRUCTIVE UROPATHY FROM NON-OBSTRUCTIVE UROPATHY TAKING INTRAVENOUS UROGRAM AS GOLD STANDARD.

Abstract

Introduction

Renal Obstruction is the most common problem in the urology world today.  Urolithiasis causing acute renal obstruction is the most frequent cause. Early and accurate diagnosis can overcome the deteriorating effects of obstruction on the urinary tract. Computed tomography pyelogram now a day is considered to be the gold standard investigation for urolithiasis. For assessment of acute renal colic, plain abdominal radiography, Ultrasound, and Intravenous urography are used as first-line diagnostic tools. Doppler and conventional Ultrasound are modalities of choice in patients with renal colic. Conventional Ultrasound alone cannot readily distinguish an obstructed from a non-obstructed dilated renal collecting system, whereas with the help of Doppler Ultrasound using a resistive index to quantify changes in intrarenal arterial Doppler Ultrasound waveforms, it results in increasing the diagnostic accuracy of ultrasound in patients with urinary obstruction.

Material and methods

This was a cross-sectional study conducted at the Radiology department of a tertiary care hospital. A total of 100 patients with the complaint of acute unilateral flank pain with suspicion of acute obstructive uropathy was included in this study. The patient’s Doppler Ultrasound was done. Mean intrarenal RI and difference in mean RI of the obstructed and contralateral kidneys (∆RI) were calculated and patients were labeled as positive or negative. This is followed by Intravenous urography. SPSS version 20 was used for data entry and analysis.

Results

The mean age of the patients was 31.90±6.12 years. There were 87 patients whose IVU was positive whereas Doppler ultrasound findings were positive in 85 patients. The sensitivity and specificity of Doppler ultrasound were 97.7% and 100%. While PPV and NPV of Doppler ultrasound were 100% and 86.67% respectively.

Conclusion

Intra renal resistive index on Doppler ultrasound is a useful diagnostic tool that can be effectively used to differentiate acute obstructive uropathy from non-obstructive uropathy with the sensitivity of 97.7%.