Predictors of time-to-nadir serum creatinine after drainage of bilaterally obstructed kidneys due to bladder cancer

Background: There are persistent controversies about the outcomes and benefits of drainage of malignant ureteral obstruction by percutaneous nephrostomy (PCN). This study aimed to assess the predictors of the time-to-nadir (TTN) of serum creatinine (SCr) levels after drainage of bilaterally obstructed kidneys (BOKs) due to bladder cancer (BC) by PCN.Materials and methods: This prospective nonrandomized study included patients with BOKs due to BC treated by PCN between April 2019 and March 2022. The primary outcome measure was TTN.Results: Of the 55 patients with a median age (range) of 66 years (47-86 years), 32 (58.2%) had a normal nadir SCr and 23 (41.8%) had a high nadir SCr within 21 days after drainage of BOKs due to BC. High nadir SCr was associated with a higher mean age (p = 0.011) and lower body mass index (BMI, p = 0.043). However, patients with normal nadir SCr had a significantly shorter TTN (p = 0.023) and an increased mean SCr trajectory (p < 0.001) during TTN. In multivariate analysis, low urine output at presentation (p = 0.021) and high BMI (p = 0.006) were associated with longer TTN. However, the mean parenchymal thickness (p = 0.428) and laterality of drainage (p = 0.466) were not associated with the mean TTN and SCr normalization rates. According to the modified Clavien-Dindo classification, 8 cases of hematuria were managed conservatively (grade 2), and 2 cases of PCN slippage were repositioned using local anesthesia (grade 3).Conclusions: Despite the safety of PCN for drainage of BOKs due to BC, more than 41% of the patients failed to have a normal nadir SCr. Predrainage low urine output and high BMI were associated with longer TTN. Laterality of drainage had no significant effects on the TTN and SCr trajectory.