Gastropyeloplasty: A swine model

Objectives. Struvite calculus formation requires an alkaline urinary pH. An acidic urinary pH will dissolve struvite calculi and prevent recurrent str uvite stone formation. Long-term urinary acidification has been unsuccessfu l. We sought to determine whether a gastric patch (with viable parietal cel ls) anastomosed to the renal pelvis could create an acidic urinary milieu. Methods. A vascularized stomach patch (from the greater curvature) was anas tomosed to the left renal pelvis in 15 female pigs. The right kidney was us ed as a control. The first 6 pigs were used to refine the surgical techniqu e. The remaining 9 pigs were subjected to a formal gastropyeloplasty and fo llowed up for 4 weeks. Urine was collected before and after stimulation wit h pentagastrin. Urine pH was measured from both kidneys in response to gast rin stimulation and oral intake. The kidneys, ureters, and bladders were ex amined for gross changes and histologic review. Results. The 9 test animals had more acidic urine in the control kidney tha n in the gastropyeloplasty kidney. Pentagastrin had no significant impact o n urinary pH. Hydroureteronephrosis and a concentrating defect were noted i n the treated kidney. Histologic review revealed smooth muscle hyperplasia of the left ureter and viable parietal cells in the stomach patch. Conclusions. An animal model was developed to transfer a gastric patch to t he renal pelvis. Hydronephrosis and ureteral dilation were associated with this gastric patch. We were unable to acidify the urine despite viable pari etal cells in the transposed stomach segment. Further refinements of this c oncept may be successful in acidifying urine in the hope of preventing recu rrent struvite nephrolithiasis. (C) 1999, Elsevier Science Inc. All rights reserved.