Laparoscopic anatrophic nephrolithotomy: Feasibility study in a chronic porcine model

Purpose: Anatrophic nephrolithotomy performed via open surgery involves incising the renal parenchyma along an avascular plane to remove a large, complex renal stone. We determined the feasibility of performing laparoscopic anatrophic nephrolithotomy in a survival porcine model. Furthermore, we present a novel technique of creating a staghorn calculus in the porcine model. Materials and Methods: After developing the technique in 3 pigs the survival study was performed in 10 consecutive animals. The procedure comprised 2 aspects. 1) We developed an animal model for staghorn calculi by retrograde injection of polyurethane (Fomo Products, Inc., Norton, Ohio) into the renal pelvis through a ureteral catheter. For a 2-week period the staghorn calculus was allowed to create hydronephrosis. 2) Laparoscopic anatrophic nephrolithotomy was done, involving control of the renal artery and vein, in situ renal hypothermia with ice slush in 1 animal, lateral renal parenchymal incision, stone extraction and suture repair of the incised collecting system and renal parenchyma. Results: Synthetic stone formation and laparoscopic anatrophic nephrolithotomy were successful in all 10 animals, including 1 that underwent staged bilateral anatrophic nephrolithotomy. Mean operative time for anatrophic nephrolithotomy was 125 minutes. Mean blood loss was 68 cc and mean warm ischemia time was 30 minutes (range 23 to 39). A residual small pelvicaliceal calculus was noted postoperatively in the initial 3 cases only. Thereafter, routine intraoperative ultrasonography and flexible endoscopy were done for stone localization, resulting in a stone-free rate of 100% in all 7 remaining animals. Diethylenetriamine pentaacetic acid renal scans documented improvement in the glomerular filtration rate from a mean of 26.4 ml. per minute after stone creation and hydronephrosis to 54.8 ml. per minute 4 to 5 weeks after laparoscopic anatrophic nephrolithotomy. Conclusions: Laparoscopic techniques can be applied to complex stone surgery such as anatrophic nephrolithotomy with encouraging surgical and functional outcomes. To our knowledge this report represents the initial study of in situ creation of experimental staghorn calculi and laparoscopic anatrophic nephrolithotomy performed completely intracorporeally in a chronic porcine model.