Abstract: Objective To explore the relationship between the degree of hydronephrosis and the bleeding-related complications following percutaneous nephrolithotomy.
Methods The data of 133 patients who underwent single-tract(F20) percutaneous nephrolithotomy in our hospital from September 2018 to April 2020 were retrospectively analyzed.All patients with single upper ureter or UPJ or renal pelvis stones,or the above stones accompanied by lower calyx stone less than 1cm were included.According to the degree of hydronephrosis before operation,patients were divided into no hydronephrosis or mild hydronephrosis group(group A,n=49),moderate hydronephrosis group(group B,n=37) and severe hydronephrosis group(group C,n=47).All operations were performed under ultrasound-guided puncture to establish F20 percutaneous renal access.All patients' characteristics,surgery-related parameters,and incidence of obvious bleeding-related complications were obtained.
Results All operations were successfully completed.There were 3 cases of obvious bleeding complications in the group A,of which 1 case was treated with angioembolization;4 cases of group C had obvious bleeding after operation,of which 1 case underwent angiography and embolization.No obvious bleeding complications occurred in group B.Multivariate regression analysis showed that moderate hydronephrosis and preoperative hemoglobin levels were independent influencing factors for postoperative bleeding-related adverse events.
Conclusion The degree of hydronephrosis may have an important effect on the risk of bleeding after percutaneous nephrolithotomy.The possible reason is that the degree of difficulty in accurately identifying the fornix of the calyx and dilation under different degrees of hydronephrosis when establishing the access varied.

Key words: kidney stones, hydronephrosis, percutaneous nephrolithotomy, hemorrhage