Effects of balloon dilatation on canine ureteric physiology.

The concept of adynamic ureteric obstruction following balloon dilatation was explored in 12 female mongrel dogs. Upper ureteric segments were dilated to 15 french at 10 atm for 3 min. Pressure and motility in the dilated segments were compared to that proximal and distal to the dilated segment prior to, immediately after, and at 2 and 6 weeks after dilatation. Immediately after dilatation the dilated segment and proximal pelvi-ureter showed a rise in baseline pressure from 2.5 +/- 0.3 and 1.9 +/- 0.3 to 32 +/- 4.6 and 37.2 +/- 5.7 mm Hg, with an associated decrease in the amplitude of contractions. Distal ureteric pressure/motility was unaffected at this point. At 2 weeks, the motility of the pelvis, dilated segment and distal ureter was diminished. Nephrostograms showed hydronephrosis and dilated upper ureteric segments with extravasation in 2 animals. At 6 weeks there was residual dilatation but motility of the dilated segment, and that of the proximal pelvi-ureter and distal ureter had returned to normal.