Sm. Donnellan et al., Gastric patch pyeloplasty: Development of an animal model to produce uppertract urinary acidification for treating struvite urinary calculi, J UROL, 166(2), 2001, pp. 684-687
Purpose: Struvite calculi form in an alkaline environment created by urease
producing uropathogens. We developed a viable upper tract urinary acidific
ation model by performing gastric patch pyeloplasty in the rabbit. This mod
el produces urinary acidification sufficient for the treatment and preventi
on of struvite renal calculi. We evaluated the physiological, metabolic and
surgical outcomes.
Materials and Methods: A gastric segment was harvested based on branches of
the left gastro-epiploic artery. The flap was folded along the transverse
axis and the adjacent edges were closed. The mouth of this reconfigured pou
ch provided optimal dimensions for anastomosis with the diminutive renal pe
lvis. Half of the rabbits were treated with internal stenting and H-2 block
ade. Urinary pH was assessed by weekly cage collection and direct collectio
n from the cannulated ureters. Urine culture was done, and serum gastrin an
d electrolytes were assessed at regular intervals. The rabbits were sacrifi
ced at 3 to 26 weeks. Histological examination was routinely performed.
Results: A total of 15 rabbits were available for complete assessment. Sust
ained urinary acidification was produced in 7 animals (47%) with a mean pH
decrease of 2.27. In another 2 rabbits (13%) the urine was initially acidic
but subsequently became alkaline due to ureteral obstruction. Electrolytes
and gastrin were unchanged in these rabbits and urine culture was positive
in 2. Histological testing revealed nonspecific inflammatory changes of th
e renal pelvis. Anastomotic complications were the most common surgical com
plication and the most common cause of failed acidification. The cohort tre
ated without stents and H-2 blockade was at significantly greater risk for
anastomotic leakage.
Conclusions: Gastric patch pyeloplasty may significantly increase urinary a
cidity in the rabbit model without altering the serum electrolyte balance o
r gastrin level. The procedure utilizes common techniques of reconstructive
urology and may be possible with laparoscopy. Further study is required to
assess the in vivo effect of this procedure for treating and preventing up
per tract struvite calculi.