Kim HY, et al. - This study intended to determine the risk factors for severe bleeding requiring angioembolization among individuals who received transfusions after percutaneous nephrolithotomy (PCNL), especially those who underwent anatomically incorrect renal puncture. Researchers recruited a sum of 53 individuals, who received transfusions after PCNL and simultaneously had a postoperative CT scan conducted between November 2009 and May 2019 at two teaching hospitals. Individuals were classified into two groups: those who underwent angioembolization and those who did not. Between the two groups, patient, stone and procedural factors were compared. After PCNL, incorrect renal puncture was associated with severe bleeding requiring angioembolization.  The outcomes suggested the importance of the basic principle of renal puncture for PCNL.