Diuretic enhanced duplex Doppler sonography in 33 children presenting with hydronephrosis: a study of test sensitivity, specificity and precision

Abstract

Purpose: We assessed the value of diuretic enhanced Doppler sonography in the diagnosis of pediatric renal obstruction as well as its reproducibility, sensitivity and specificity.

Materials and methods: We studied 33 children (68 kidneys) by standard diagnostic techniques and diuretic Doppler sonography. A total of 20 obstructed kidneys was compared to 48 without obstruction and we performed surgery on 13. An average of 2.3 resistive index measurements were made per test and 436 total resistive index values were assessed by Student's t distribution and chi-square analysis before and after surgical repair. The assessor was blinded to the clinical diagnosis.

Results: The obstructed mean resistive index before (0.71) and after (0.74) furosemide administration differed significantly from the nonobstructed mean resistive index (0.65, p < 0.02). Postoperative mean resistive index (0.68) was not affected by the diuretic and did not differ from the mean resistive index of nonobstructed kidneys. Resistive index test sensitivity was 76% and specificity was 88%. The precision for 3 values per test was +/- 0.11.

Conclusions: When at least 3 values are obtained per test, diuretic Doppler sonography predicts the actual resistive index average with 98% confidence limits 90% of the time.