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5089444 
Journal Article 
Effect of positioning on ureteric stone retropulsion: 'gravity works' 
Patel, RM; Walia, AS; Grohs, E; Okhunov, Z; Landman, J; Clayman, RV 
2019 
Yes 
BJU International
ISSN: 1464-4096
EISSN: 1464-410X 
123 
1 
113-117 
English 
30098120 
OBJECTIVE: To evaluate the potential impact of alterations in 'patient' position on laser-induced ureteric stone retropulsion in an in vitro model.

MATERIALS AND METHODS: A ceramic (phantom) stone was placed in a water-filled clear polymer tube and subjected to continuous laser energy until the stone had retropulsed a distance of 10 cm. The trial was stopped after 60 s if the stone had not reached 10 cm. The time and total energy needed to cause 10 cm of retropulsion were recorded at incline angles of 0°, 10°, 20°, and 40°; 10 trials at each angle were completed. The study was then repeated with pure calcium phosphate brushite stones.

RESULTS: Retropulsion decreased with increasing incline angle of the saline-filled clear polymer tube. At 0° of incline the phantom stone reached a distance of 10 cm after 7.4 s. At 10°, 20° and 40°, the phantom stone migrated a mean maximum distance of 3.1, 1.2 and 0.7 cm, respectively, and the trial was stopped after 60 s. For the calcium phosphate stone, at 0° and 10° of incline, the stone reached 10 cm after 6.9 and 42.8 s, respectively (P < 0.05). At 20° and 40°, the calcium phosphate stone moved a mean maximum distance of 2.4 and 1 cm, and the trial was stopped after 60 s.

CONCLUSION: Alterations in the angle of inclination reduced stone retropulsion during ureteroscopic lithotripsy in an in vitro model to <1 cm. Increasing the incline angle of a patient may effectively preclude retropulsion when performing laser lithotripsy of ureteric stones.