A PROSPECTIVE RANDOMIZED TRIAL COMPARING 2 DIURESIS RENOGRAPHY TECHNIQUES FOR EVALUATION OF SUSPECTED UPPER URINARY-TRACT OBSTRUCTION IN CHILDREN

Purpose: We compare the diagnostic impact of 2 diuresis renography tec hniques for evaluation of suspected upper urinary tract obstruction in children. Materials and Methods: A total of 72 children were randomly assigned to 1 of 2 standardized diuresis renography protocols. The pr otocols were identical, except for the time of furosemide (F) injectio n. In the F+20 scans furosemide was given 20 minutes after the (99m)te chnetium pentetic acid radiopharmaceutical. With the modified F-15 sca ns furosemide was injected 15 minutes before renography. Hydration, bl adder catheterization, urine output determination, radiopharmaceutical injection and scan acquisition were identical. Renography outcomes (o bstructed, nonobstructed or equivocal) were analyzed for the investiga ted side(s) and for the contralateral side, which was used as a contro l in children with suspected unilateral obstruction. Chi-square test w as used to compare the percentage of obstructed and nonobstructed scan s of both protocols. Fisher's exact test was used to compare the nonob structed scans and equivocal results of both protocols. Results: Of th e 96 scans performed 8 were excluded because of technical problems. Th e remaining scans included 44 F+20 and 44 F-15. Of the 88 scans 10 wer e used to evaluate possible bilateral obstruction. A total of 48 boys and 24 girls were evaluated. Because 2 children had a solitary kidney each, the total number of renal units studied for outcome was 174. The F-15 scan showed 7 times more obstruction than the F+20 scan on the i nvestigated side, and this difference was statistically significant. N o obstruction was diagnosed on the contralateral side with either tech nique when used to investigate cases of suspected unilateral obstructi on. Conclusions: The timing of the furosemide injection (F-15 scan ver sus F+20) has a significant impact on the obstructive versus nonobstru ctive renography results when evaluating children with suspected upper urinary tract obstruction.