# Retrograde pyeloperfusion: a novel technique to prevent stone fragment migration into the ureter during percutaneous nephrolithotomy

## TL;DR

A new technique called retrograde pyeloperfusion reduces stone fragment migration into the ureter during kidney stone surgery.

## Contribution

Retrograde pyeloperfusion is introduced as a novel method to prevent stone fragment migration during percutaneous nephrolithotomy.

## Key findings

- RP significantly reduced stone fragment migration in normal and moderately hydronephrotic models compared to control and UAS.
- In severe hydronephrosis, RP still reduced migration compared to UAS but not significantly compared to control.
- RP showed 73.3–85.7% reduction in stone fragment migration across all models.

## Abstract

To determine whether retrograde pyeloperfusion (RP) during percutaneous nephrolithotomy (PCNL) decreases antegrade ureteral stone fragment migration, normal, moderately, and severely hydronephrotic silicone kidney and ureter models were created using deidentified CT images. Two techniques to prevent fragment migration, ureteral access sheath (UAS) and RP via a ureteroscope, were compared to an empty ureter. Two grams of stone fragments were placed into the renal pelvis. Antegrade irrigation and suction were applied for 5 min. The weights of ureteral stone fragments were compared using the Kruskal-Wallis test (p < 0.05 significant). In the normal ureter model, RP significantly reduced ureteral stone fragment migration (0.06±0.03 g) compared to both the UAS (0.32±0.19 g; p = 0.047) and control (0.42±0.11 g; p = 0.009). Similarly, in the moderate hydroureter model, RP significantly reduced ureteral stone fragment migration (0.11±0.06 g) compared to both the UAS (0.68±0.18 g; p = 0.009) and control (0.48±0.15 g; p = 0.016). In the severe hydroureter model, RP reduced ureteral stone fragment migration (0.17±0.12 g) compared to the UAS (1.04±0.29 g; p = 0.026) but was similar to the control (0.65±0.37 g; p = 0.169). RP showed an 85.7% and 81.1% reduction compared to the control and UAS conditions in the normal model, 76.2% and 83.3% reduction in the moderate hydroureter model, and 73.3% and 83.2% reduction in the severe hydroureter model, respectively. Thus, compared to an empty ureter and a UAS, in all ureter models, RP reduced ureteral stone fragment migration by 73.3–85.7%. Retrograde pyeloperfusion should be considered to reduce ureteral stone fragment migration during PCNL when endoscopic combined intrarenal surgery is employed.