Increased intra-abdominal pressure results in both obstructive and nonobstructive types of impairments of renal pelvic excretion

Abstract

An experimental study has been conducted toevaluate the effects of increasedintra-abdominal pressure (IAP) on the excretionfunction from renal pelvis into the ureter.Methods: Sixteen adult male New Zealandrabbits were randomly allocated in two groupsafter obtaining basal scintigraphies. Group Iconsisted of 8 rabbits which were subjected toan increased IAP for ten day period. In GroupII an other 8 rabbits were subjected to anincreased IAP for 60 day period. At the end ofthe periods of increased IAP the post-pressurescintigraphic evaluations of both groups werecarried out. Time to maximum activity(T_max), T_1/2 and T_2/3 values ofthe radiopharmaceutical in the kidneys and downslope parameters (DS_1/2, DS_2/3)were calculated from the renogram curves ofboth right and left kidneys. Comparison ofbasal and post-pressure scintigrapies and themean difference of the renogram parametersbetween groups were performed.Results: All basal scintigraphies werenormal. Post-pressure scintigraphies revealedan obvious delay in the excretion phase in bothgroups. Both kidneys of a rabbit in group Irevealed a non-obstructive pattern throughresponding well to administration of diuretic.Furthermore both kidneys of a rabbit from groupII have revealed an obstructive pattern.T_1/2 and T_2/3 values weresignificantly elevated and mean DS_1/2,DS_2/3 were significantly decreased inpost-pressure scintigraphies of the both groupswithout revealing a statistically significantdifference between groups I and II. The meandifference of T_max was significantlyincreased in group II.Conclusion: The increases in IAP, throughthe compressive effect upon ureters togetherwith a concomitant increase in intravesicalpressure, may impair the passage of urine fromrenal pelvis into ureter. The impaired passagemay play a role in the development of hydronephrosis which may either reveal anonobstructive and/or obstructive pattern.