Active deflection of scopes and the availability of accessories, such as nitinol baskets and holmium laser, have also enabled the increasing application of flexible ureteroscopy for renal calculi, Dr. Desai added.
One advantage of flexible ureteroscopy is fragmentation of stone under direct visualization. “It doesn’t have the unpredictability of shock-wave lithotripsy,” he said.
Other advantages include the ability to reposition fragments into a favorable location, basket removal of some stone burden, and proper identification of parenychmal calcifications.
Recent studies also indicate that flexible ureteroscopy can be performed in patients on active coagulation without hemorrhagic or thromboembolic complications, he said.
Complete removal of staghorn calculi is mandatory, as these stones are associated with high rates of morbidity, mortality, persistent infection, and rapid stone regrowth.
For staghorn calculi, Dr. Desai recommends aggressive PNL, or “multiperc” [multiple percutaneous access]. Multiperc is the philosophy of completely clearing all calculi using multiple tracts and/or sittings, with SWL reserved for the occasional patient in whom percutaneous clearance is either dangerous or unfeasible.
Multiperc offers the capability for complete stone clearance in a single hospitalization with a reduced need for ancillary procedures and re-treatments.
Examining multiperc results over a 13-year period during which 650 kidneys were treated reveals a complete clearance rate of 85%, a need for ancillary procedures 9% of the time, and a 91% final clearance. Thirty-two percent of the cases were managed with a single tract, 36% needed two tracts, and 12.4% required more than three.
The potential impact on renal function has been a concern with multiperc, but percutaneous nephrostomy tracts appear to cause minimal change in renal function, said Dr. Desai. “There is a slight decrease [during] the immediate postoperative period in creatinine clearance and estimated glomerular filtration rate but a marginal improvement in kidney function [as ascertained by CKD class] at one year,” he said. “The overall impact on renal function was positive.”
Kukreja and colleagues in 2003 showed that PNL in patients with preoperative renal insufficiency resulted in normalization of kidney function in one third and an improvement in another 47%. Pre-existing conditions, such as proteinuria and infection, were significant predictors of long-term renal function.
For patients with renal insufficiency, technical modifications, including staging (less than 90 minutes of nephroscopy time), prior nephrostomy drainage, hydration, and antibiotics, may be necessary to preserve renal function.
Multiperc does result in blood loss that was associated with a mean drop in hemoglobin of 1.9% and higher loss with multiple tracts. The procedure-specific transfusion rate is about 11%. Aside from multiple tracts, other factors that affect blood loss during PNL are previous open surgery or PNL, an operative time greater than 90 minutes, intraoperative complications, and diabetes. PNL appears safe in anticoagulated patients, he said.