DIURETIC DOPPLER SONOGRAPHY FOLLOWING SUCCESSFUL REPAIR OF RENAL OBSTRUCTION IN CHILDREN

The measurement of resistive index (RI = [peak systolic velocity - end diastolic velocity]/peak systolic velocity) by Doppler sonography has demonstrated variable reliability as an indicator of pediatric urinar y obstruction. By modifying Doppler studies with the addition of furos emide (diuretic Doppler sonography), we previously found significant d ifferences between 10 nonobstructed and 10 obstructed kidneys in child ren (median age 7 months). The obstructed kidneys have since undergone surgical repair, and postoperative reevaluation has been performed by diuretic Doppler sonography and diuretic renography. Diuretic Doppler sonography was performed on well hydrated catheterized patients, with resistive index measurement of the renal interlobar and arcuate arter ies obtained before and 10 minutes after 1 mg./kg. furosemide infusion . Following surgical repair of obstruction all 10 kidneys had stable g lomerular filtration rate with improved pelvic emptying times as demon strated by half-time. Of 6 kidneys evaluated by diuretic Doppler sonog raphy before 3 months 2 had resistive index levels greater than 75. Of the 9 kidneys measured at 3 months or more postoperatively all had re sistive index values of less than 75, even after furosemide infusion ( 5 kidneys underwent repeat evaluation). In our study the previously de monstrated post-diuretic elevation of resistive index in pediatric uri nary obstruction was eventually reversed following surgical repair. Di uretic Doppler sonography appears to be a promising noninvasive method for evaluating pediatric hydronephrosis, providing an alternative phy siological parameter with which to measure renal obstruction.