Flank position ureterorenoscopy: new positional approach to aid in retrograde caliceal stone treatment

Clearance of lower pole stones and complex maneuvers such as basket repositioning remain challenging in ureteroscopic treatment of caliceal stone burdens. We describe the initial use of flank position ureteroscopy (FPU) with modifications to aid in the treatment of complex caliceal urolithiasis. We hypothesized that gravitational force acting on caliceal stones and fragments during holmium laser treatment would result in fragments being repositioned into the dependent renal pelvis, allowing enhanced treatment.

Eleven patients with complex upper tract stone disease (aggregate stone burden 1.5-5 cm) were treated using FPU. Patients were positioned with the stone-containing side superior. Flexible cystoscopy followed by flexible ureterorenoscopy and intracorporeal lithotripsy were performed. We utilized several modifications of the technique, including a radiolucent table and rotational C-arm fluoroscopy unit. Once all stones and particles fell into the dependent renal pelvis, additional laser fragmentation was simple.

We observed the expected advantage of gravitational drainage of particles and stone into the renal pelvis during procedures. In many cases, fragments passed partially down the ureter during treatment. Basket repositioning of stones was not necessary. One complication, collecting system perforation during access, was treated with stent placement and successful delayed FPU. Seven patients were stone free at follow-up. Four patients with stone burdens >3 cm had approximately 80% stone burden reduction, but residual asymptomatic lower-pole particles (2-6 mm) remained, with several clearing with a secondary procedure.

The use of FPU for the performance of complex renal stone treatment is a useful aid. Further refinement and comparison with standard technique is ongoing.