RENAL DOPPLER ULTRASONOGRAPHY IN CHILDREN WITH EQUIVOCAL OBSTRUCTIVE UROPATHY - EFFECT OF INTRAVENOUS NORMAL SALINE FLUID LOAD AND FRUSEMIDE

Objective To study the effect of hyperhydration with normal saline and frusemide on the renal resistive index (RI) in children with equivoca l obstructive uropathy, Patients and methods Twelve children (24 kidne ys) with unilateral or bilateral hydronephrosis underwent isotopic diu retic renography and Doppler ultrasonography. All children had equivoc al obstruction of the hydronephrotic kidneys with half-time drainage ( T/2) values of 10-20 min. Doppler studies were carried out both at bas eline and after the infusion of normal saline and frusemide, Results O f the 24 kidneys, five were normal and 19 were hydronephrotic; compare d with normal kidneys, the hydronephrotic units had a significantly lo wer glomerular filtration rate (GFR) and longer T/2, At baseline, the mean RI values of normal and hydronephrotic kidneys were not significa ntly different (0.70, SD 0.03 and 0.71, SD 0.04, respectively). After the infusion of saline and frusemide, the mean RI of hydronephrotic ki dneys (0.67, SD 0.07) was significantly (P=0.01) higher than that of n ormal kidneys (0.60, SD 0.02), but the response of RI in hydronephroti c kidneys was variable. Based on the RI at baseline and after infusion , hydronephrotic kidneys could be categorized into three groups. Group 1 (n=6) had an RI<0.7 before and after infusion, group 2 (n=6) had a baseline RI>0.7 and <0.7 after infusion, and in group 3 (n=7) both RIs were >0.7. Kidneys in group 3 had the lowest GFR and the highest T/2 values. Five of these seven hydronephrotic kidneys eventually had dete riorating GFRs requiring surgical correction; the GFR of the remaining hydronephrotic kidneys remained stable. Conclusion In children with e quivocal obstructive uropathy based on diuretic renography, the determ ination of RI before and after infusion of normal saline and frusemide could be helpful in distinguishing obstructed from non-obstructed kid neys.