Impact on ureteral peristalsis in a stented ureter. An experimental study in the pig.

Peristalsis was examined in ten pigs with stented ureters. In five of the animals, the stents were inserted 6-8 weeks before examination, which was performed using a 3.5 Ch catheter equipped with thin copper wires in two sites 10 cm apart. This set-up enabled an analysis of the frequency, direction and velocity of the peristaltic waves to be made. When diuresis was gradually raised, the frequency and velocity of the contractions usually increased in normal ureters, whereas we observed a decline in both of these parameters. There was a statistically significant difference in the lower frequency in the long-term stented animals. Retrograde peristalsis, aberrant waves and incomplete contractions were common in the ureters after prolonged stenting, and urine flow was greater around than through the stent. Our results suggest that the flow of urine is obstructed by a ureteral stent, and they support clinical data showing that such devices prolong the time it takes for a stone to pass to the bladder.