Double pigtail ureteric stent versus percutaneous nephrostomy: effects on stone transit and ureteric motility

The effects of double pigtail ureteric catheters (JJS) and percutaneous nephrostomies (PN) on ureteric motility and artificial stone transit was assessed in 12 dogs. Each animal underwent bilateral nephrostomies and an artificial stone insertion into each upper ureter (n = 20). A 4-Fr JJS was inserted on one side (group 1) while a PN was left on the contralateral side (group 2). In 4 stone-only 'control' ureters (group 3), the PN was sealed after 72 h. Stone passage was assessed by plain x-rays. Pelvic and ureteric motility was assessed prior to stone insertion and again at 2 weeks.

In group 1, only 1 of 8 stones (12.5%) passed completely. Four reached the midureter, 3 remained static. Six of 8 stones (75%) in group 2 passed completely. Two stones remained in the distal ureter. All 4 stones (100%) in group 3 passed by day 3 postoperatively. At laparotomy the J-stented ureters were dilated and both pelvic and ureteric contractions were diminished. Ureteric diameter was normal on the PN side. The ureters contracted with normal amplitude, but diminished rate of contraction above the stones in the ureters with residual calculi (n = 2), and in the 6 ureters from which spontaneous stone passage had occurred. A similar pattern was found in the 4 group 3 ureters.

Double J stents are associated with ureteric dilatation, diminished peristalsis and impaired stone passage. APN preserves ureteric peristalsis and facilitates stone passage. In the initial phase, raised hydrostatic pressure appears to the most important factor determining stone passage.