PARTIAL URETERAL OBSTRUCTION - A STUDY OF DOPPLER ULTRASONOGRAPHY ANDDIURETIC RENOGRAPHY IN DIFFERENT GRADES AND DURATIONS OF OBSTRUCTION

Objectives To study the changes in renal resistive index (RI) and rena l function with time during different grades of partial unilateral ure teric obstruction, and to determine the correlation between the ultras onographic and renographic findings. Materials and methods Ten dogs un derwent right partial ureteric obstruction; grade 1 (mild) obstruction was applied in five dogs (group A) and grade 3 (moderate and severe) obstruction in the other five (group B). All dogs were assessed using excretory urography, diuretic renography with the calculation of half- time drainage (T-1/2) and bilateral renal Doppler ultrasonography befo re the experiment began, after one week of obstruction, and every 2 we eks during 8 weeks of obstruction. Results In both groups, after the i nduction of light ureteric obstruction, there was a progressive decrea se of effective renal plasma flow (ERPF) and a progressive increase of the RI of the right kidney at the end of the first and second weeks o f obstruction, with an almost stable value thereafter, The decrease of ERPF and the increase of RI in the right kidney were correlated with the degree of obstruction. There was also a dramatic increase of T-1/2 of the right kidney that correlated with the degree of obstruction, C oncomitantly, there was a significant compensatory increase of ERPF an d a significant decrease of the: RI of the left kidney in both groups. The compensatory increase in ERPF limited the loss in total ERPF in b oth groups. The contribution of obstructed kidney to the total ERPF wa s significantly reduced in both groups. At the end of the eighth week, taking all kidneys together, there was a statistically significant ne gative correlation between the ERPF and RI, and between ERPF and T-1/2 and a positive correlation between T-1/2 and RI. Conclusions Unilater al partial ureteric obstruction increased the RI and T-1/2 and decreas ed the ERPF of the corresponding kidney, together with a decrease of R I and an increase in ERPF of the contralateral kidney. The more severe the obstruction, the greater the increase in RI and T-1/2 and the dec rease in ERPF. After the obstruction stabilized, RI and T-1/2 were pos itively correlated.