Effects of severe hydronephrosis on surgical outcomes of minimally invasive percutaneous nephrolithotomy (MPCNL)

INTRODUCTION: The impact of severe hydronephrosis on the outcomes of minimally invasive percutaneous nephrolithotomy (MPCNL) remains controversial; it is still a subject well worth exploration. AIM: To investigate the effects of severe hydronephrosis on surgical outcomes of MPCNL, especially on operative time (OT) and stone-free rate (SFR). MATERIAL AND METHODS: In total, 301 patients who underwent MPCNL were included in this study and divided into 4 groups according to the degree of hydronephrosis (nil, mild, moderate, and severe hydronephrosis, respectively). Univariate analyses and multivariate logistic analyses were used to determine the risk factors affecting OT and SFR. RESULTS: Patients with severe hydronephrosis had a longer OT (p < 0.001), a decreased SFR (p < 0.001), and a higher postoperative haemoglobin drop and blood transfusion rate compared to the other 3 cohorts (p = 0.011 and p = 0.043, respectively). Univariate analyses determined that severe hydronephrosis, calyx for access, stone location, stone type, stone size, and number of tracts significantly correlated with OT, while severe hydronephrosis, stone location, stone type, and stone size showed a strong association with SFR (all p < 0.05). Multivariate analyses further identified that severe hydronephrosis (OR = 3.496, p = 0.013), stone location (≥ 4 calyces: OR = 3.024, p = 0.017), stone type (staghorn: OR = 5.204, p = 0.002), and stone size (≥ 1600 mm(2): OR = 12.669, p < 0.001; 800–1599 mm(2): OR = 5.194, p < 0.001) were significant risk factors affecting OT, while SFR was independently influenced by stone type (staghorn: OR = 4.377, p = 0.039; multiple: OR = 3.778, p = 0.044), stone location (≥ 4 calyces: OR = 4.413, p = 0.020; 2–3 calyces: OR = 3.617, p = 0.034), and severe hydronephrosis (OR = 7.093, p = 0.001). CONCLUSIONS: Severe hydronephrosis is a significant risk factor that can lead to longer OT and lower SFR, and correlates with increased risk of bleeding and blood transfusion rate in some cases during MPCNL. Accordingly, severe hydronephrosis is an influential factor that should not be ignored when performing MPCNL.