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

UNLABELLED: An experimental study has been conducted to evaluate the effects of increased intra-abdominal pressure (IAP) on the excretion function from renal pelvis into the ureter.

METHODS

Sixteen adult male New Zealand rabbits were randomly allocated in two groups after obtaining basal scintigraphies. Group I consisted of 8 rabbits which were subjected to an increased IAP for ten day period. In Group II an other 8 rabbits were subjected to an increased IAP for 60 day period. At the end of the periods of increased IAP the post-pressure scintigraphic evaluations of both groups were carried out. Time to maximum activity (Tmax), T1/2 and T2/3 values of the radiopharmaceutical in the kidneys and down slope parameters (DS1/2, DS2/3) were calculated from the renogram curves of both right and left kidneys. Comparison of basal and post-pressure scintigrapies and the mean difference of the renogram parameters between groups were performed.

RESULTS

All basal scintigraphies were normal. Post-pressure scintigraphies revealed an obvious delay in the excretion phase in both groups. Both kidneys of a rabbit in group I revealed a non-obstructive pattern through responding well to administration of diuretic. Furthermore both kidneys of a rabbit from group II have revealed an obstructive pattern. T1/2 and T2/3 values were significantly elevated and mean DS1/2, DS2/3 were significantly decreased in post-pressure scintigraphies of the both groups without revealing a statistically significant difference between groups I and II. The mean difference of Tmax was significantly increased in group II.

CONCLUSION

The increases in IAP, through the compressive effect upon ureters together with a concomitant increase in intravesical pressure, may impair the passage of urine from renal pelvis into ureter. The impaired passage may play a role in the development of hydronephrosis which may either reveal a nonobstructive and/or obstructive pattern.