UASs were advance into 20 fresh ex vivo porcine kidney-ureters, either with or without SWs. The average and max force of insertion were recorded. Retrograde saline injection was used to identify the presence of lacerations.
For SW vs no SW, the mean insertion force (1.79 vs 0.67, P = .0003, respectively) and max insertion force (2.29 kg vs 1.00, P = .0007) was greater in the SW group. There were 9 lacerations, 6 of which were partial and 3 complete. Of the partial injuries, 2 were in the no SW group and 4 were in the SW group. Of the complete lacerations, 2 occurred in the no SW group and 1 in the SW group. However, there was no significant difference in the total number of lacerations (P = 1.00), the number of partial lacerations (P = .628), or the number of complete lacerations (P = 1.00) between the 2 groups.
The use of an SW significantly increases the force required to insert a UAS; however, it does not appear to affect the force or the degree of ureteral injury.