The impact of unilateral ureteral obstruction on pelvic and parenchymal transit times in the pig kidney

In 10 female pigs a partial unilateral ureteral obstruction was investigated for 3 weeks. The pigs were monitored with 131I-iodo-hippuran scintigraphies before obstruction and once a week during the course of obstruction. Parenchymal and pelvic mean transit times were calculated by deconvolution analysis. Before the pigs were killed, pelvic pressure and volume were measured. During the course of obstruction there was a slight, but significant (P less than or equal to 0.05) difference in renographical split function between the 2 sides. Parenchymal transit times increased moderately ipsilaterally during the 1st and 2nd week after obstruction and a significant difference (P less than 0.02) appeared in the 2nd week compared to the contralateral side, which was unchanged during the course of obstruction. Pelvic transit times increased steadily ipsilaterally during the course of obstruction and the opposite took place contralaterally. A fair correlation (r = 0.65) was found between parenchymal transit time and pelvic baseline pressure. Pelvic transit times were prolonged at any time after obstruction and significantly correlated to the presence of obstruction. The study suggests that interpretation of the obstructed renogram will encounter analysis of both parenchymal and pelvic transit times in cases where renal function is moderately reduced.