Novel Approaches to Management of Nephrolithiasis: Minimally Invasive Techniques

In veterinary medicine, interventions for the treatment of nephroliths not amenable to medical dissolution are uncommon, largely due to the invasiveness of available treatment options. Nephroliths found incidentally have generally been monitored without intervention. Performance of nephrotomies or nephrostomy tube placement has decreased to nearly non-existent due to the procedure-associated morbidity and the lack of obvious benefits. Given the availability of less invasive treatment options, when a dog develops nephrolith-associated upper urinary tract obstruction, recurrent urinary tract infections, or chronic renal pain, stone removal should be considered. There is also evidence in human medicine that nephrolith-induced chronic kidney disease progression occurs; it is likely that these same phenomena occur in veterinary patients. Given this, nephrolith removal should be considered in appropriate cases when medical dissolution is not possible. Less invasive options such as nephroscopy, nephrolithotomy, and nephrolithotripsy allowed our team to more effectively manage nephroliths without significant morbidity. Procedures involve percutaneous placement of a sheath into the renal pelvis through the renal parenchyma. In nephrolithotomy cases, stones are removed directly through the sheath, whereas in nephrolithotripsy cases the stones are first fragmented into smaller pieces via holmium: YAG (yttrium, aluminum, garnet) laser lithotripsy or via pneumatic/ballistic forces (ie. Lithoclast) and then removed through the sheath. In dogs, we have performed these procedures minimally invasive stone removal with both a percutaneous technique and via a laparotomy assisted technique. Retrograde ureteroscopy with subsequent stone fragmentation can also be considered, however, the small ureteral lumen (even after initial stent placement) makes this very challenging. This lecture discusses decisions surrounding how to best manage nephroliths. This lecture also discusses considerations for medication management, decision making processes regarding whether stone removal should be considered, and peri-procedural considerations, such as ureteral stent placement. This lecture also discusses approaches to nephroscopy.