Risk factors and clinical course of hydronephrosis after flexible ureteroscopy

Abstract

We wanted to assess the frequency of hydronephrosis after flexible ureteroscopy (fURS), its risk factors, and long-term outcomes. We retrospectively analyzed 865 patients who underwent fURS for renal or ureteral stones from October 2011 to December 2019 and were evaluated for hydronephrosis 3 months after surgery by ultrasonography or computed tomography. Patient demographics, preoperative ureteral stents, location and diameter of stones, operative times, use of ballistic or laser devices, intraoperative ureteral injuries, and duration of the postoperative ureteral stents were evaluated. The clinical outcome was further followed for patients identified with an abnormal 3-month follow-up. At 3 months postoperatively, 48 patients developed hydronephrosis. The median stone length was 11.6 mm in all patients, and preoperative ureteral stenting was performed in most (93.5%) patients. The operation time (77 vs. 60 minutes, p < .05) was significantly longer in the group with postoperative hydronephrosis. There was no significant difference with ureteral injury. Multiple regression analysis revealed that only the operation time significantly increased the risk for postoperative hydronephrosis. Almost all patients with mild postoperative hydronephrosis had resolution or no worsening of hydronephrosis. Only one of the three patients with moderate hydronephrosis improved, but the others did not. Only the operation time was significant as a risk factor for postoperative hydronephrosis, whereas ureteral injury and the ureteral access sheath diameter were not. Mild hydronephrosis resolved spontaneously in most patients, but those with more severe hydronephrosis might require follow-up or treatment for ureteral stricture.