Percutaneous nephrolithotomy (PCNL) via single inferior-calyceal tract is suitable for some partial staghorn calculi mainly
located in the inferior calyx. A ureteral stent should be inserted at the end of PCNL to avoid urine leakage or ureteral
obstruction by residual calculi. However, antegrade ureteral stenting via the inferior calyx is not always successful due to
unfavorable lower pole calyx anatomy. In the present study, we introduced a modified method for difficult stenting. First a
0.038-inch zebra guidewire was retrogradely introduced through the previously inserted ureteral catheter and grasped out of
the work sheath by a ureteroscopic forceps to develop a through-and-through guidewire; then an 8 Fr guide catheter was
inserted antegradely over the guidewire into the ureter after removing the prior ureteral catheter; subsequently the zebra
guidewire was removed and antegradely introduced into the bladder through the guide catheter, followed by antegrade
insertion of a double J stent. Of 158 patients, 32 needed modified ureteral stenting; and the lower pole infundibulopelvic angle
(LPIA) was measured in 25 patients with and in 57 patients without modified stenting. The results showed that LPIA in
patients with modified stenting was much smaller than that in patients without modified stenting (56.0 ± 12.58 and
77.4 ± 11.40, P < 0.0001); when the LPIA is