OBJECTIVES: To study the changes in renal resistive index (RI) and renal function before and after release of different grades of partial unilateral ureteral obstructions. METHODS: Ten dogs were subjected to right partial ureteral obstruction. Grade 1 (mild) obstruction was applied to 5 dogs (group A) and grade 3 (moderate and severe) obstruction was applied to the other 5 dogs (group B). Obstruction was maintained for 8 weeks, followed by release of obstruction. All dogs were subjected to excretory urography, technetium-99m mercaptoacetyltriglycine diuretic renography with calculation of half-time drainage (T1/2), and bilateral renal Doppler ultrasonography before the start of the experiment, after 8 weeks of obstruction, and every 2 weeks during the 8 weeks after release of obstruction. RESULTS: In both groups, after induction of right ureteral obstruction, there was a dramatic decrease of effective renal plasma flow (ERPF), increase of RI, and increase of T1/2 of the right kidney. Relief of obstruction was associated with normalization of T1/2, reversal of RI, and recovery of ERPF to near basal values. No correlation was found between ERPF at the end of the recovery period and the functional parameters (T1/2, RI, or ERPF) of the obstructed kidney before release of obstruction. CONCLUSIONS: (1) Unilateral partial ureteral obstruction produces an elevation of RI and T1/2 and a fall in ERPF of the corresponding kidney. (2) After relief of function is regained with associated reversal of RI. (3) Functional parameters (T1/2, RI, or ERPF) of the obstructed kidney do not predict the recovery of ERPF after release of obstruction. (4) Rapid reversal of a previously elevated RI is an early indicator of recoverability of renal function after relief of ureteral obstruction.
OBJECTIVES: To study the changes in renal resistive index (RI) and renal function before and after release of different grades of partial unilateral ureteral obstructions. METHODS: Ten dogs were subjected to right partial ureteral obstruction. Grade 1 (mild) obstruction was applied to 5 dogs (group A) and grade 3 (moderate and severe) obstruction was applied to the other 5 dogs (group B). Obstruction was maintained for 8 weeks, followed by release of obstruction. All dogs were subjected to excretory urography, technetium-99m mercaptoacetyltriglycine diuretic renography with calculation of half-time drainage (T1/2), and bilateral renal Doppler ultrasonography before the start of the experiment, after 8 weeks of obstruction, and every 2 weeks during the 8 weeks after release of obstruction. RESULTS: In both groups, after induction of right ureteral obstruction, there was a dramatic decrease of effective renal plasma flow (ERPF), increase of RI, and increase of T1/2 of the right kidney. Relief of obstruction was associated with normalization of T1/2, reversal of RI, and recovery of ERPF to near basal values. No correlation was found between ERPF at the end of the recovery period and the functional parameters (T1/2, RI, or ERPF) of the obstructed kidney before release of obstruction. CONCLUSIONS: (1) Unilateral partial ureteral obstruction produces an elevation of RI and T1/2 and a fall in ERPF of the corresponding kidney. (2) After relief of function is regained with associated reversal of RI. (3) Functional parameters (T1/2, RI, or ERPF) of the obstructed kidney do not predict the recovery of ERPF after release of obstruction. (4) Rapid reversal of a previously elevated RI is an early indicator of recoverability of renal function after relief of ureteral obstruction.