Abstract

Purpose

To investigate the effectiveness of DISS feature of novel 7.5Fr and 9.2Fr single-use flexible digital ureteroscopes to relocate and evacuate stone fragments (2–5 mm in diameter) without any accessory instruments.

Methods

An ex-vivo experimental study on porcine kidney and ureter was performed. Natural calcium oxalate dihydrate stone fragments sized 2–5 mm placed in the upper, middle and lower calyces were used. For each stone in each location 5 attempts were performed. The attempt was defined as successful if stone evacuation was reported while withdrawing the scope through the 12/14Fr UAS. The time collapsing the collecting system was also reported.

Results

The time needed to collapse the porcine pelvi-calyceal system (PCS) was 4–5 s for 9.2Fr and 5–6 s for 7.5Fr scope. Evacuation of 2 mm stone fragments occurred in all trials both with 9.2Fr and 7.5Fr scopes. In case of 3 mm stone, evacuation of stone fragments was observed in 3 out of 5 and 1 out of 5 attempts in upper calyx, 5 out of 5 and 3 out of 5 in the middle calyx and 2 out of 5 and 0 out 5 in lower calyx using 7.5Fr and 9.2Fr scope, respectively.

Conclusion

The DISS feature of the novel 7.5Fr and 9.2Fr single-use digital flexible ureteroscope can be potentially used not only to aspirate dust but also to relocate and evacuate larger stone fragments up to 4 mm in diameter using only suction. The speed of collapse of the PCS seems to be one of the main predictors of success.