Grand Journal of Urology
E-ISSN : 2757-7163

Original Article
Objective: We aimed to compare outcomes of percutaneous nephrolithotomy (PNL) surgery in patients who had and had not undergone renal stone surgery before PNL. Material and Methods: We retrospectively analyzed the medical records of all patients who underwent PNL in our department between 2010 and 2019. Examined parameters consisted of patient demographics, medical and surgical history, stone size, stone density, stone site, estimated intraoperative blood loss, duration of operation, hospital stay and stone-free status. Results: A total of 193 patients were included the study. The mean age of the patients was 45±13 years. The mean duration of surgery was 69±11.5 minutes. The mean stone area was 720.2±600.4 mm2 and the mean stone attenuation was 982.8±327.7 HU. The mean postoperative hemoglobin decrease was 1.8±1.3 g/dL. 66 patients had previous stone surgery including open stone surgery, PNL and retrograde intrarenal surgery (RIRS). There was no statistically significant difference between patients who had and had not previousşy undergone renal stone surgery in terms of age, gender, body mass index and stone area. Operative time, estimated intraoperative blood loss, postoperative hemoglobin decreases and hospital stay were comparable between patients who had, and hed not undergone previous renal stone surgery. Stone-free rate was significantly higher in primary PNL patients compared to patients with a history of renal stone surgery (92.1% vs 77.3%, p=0.006). Conclusion: PNL has a similar complication rate in patients with and without previous kidney stone surgery. However, achieving stone-free status may be challenging in patients with a history of ipsilateral renal stone surgery.
Letter to the Editor
Dear Editor, I read the article by Huseynov et al., [] in which they examined the effects of previous renal stone surgery on percutaneous nephrolithotomy outcomes with great interest. They concluded that previous renal stone surgery increases the risk of residual stone with a similar complication rate. However, I would like to highlight some issues regarding the methodology and the results of this study. Using the method of percutaneous nephrolithotomy (PNL) in the treatment of renal stones 2 cm and greater is a gold standard according to European Association of Urology guidelines []. By increasing surgeon experience and technological development of tools using in PNL surgery increase the success of the surgery and decrease the complication rate. However, it is known that the success of PNL is also affected by some other influencers such as hydronephrosis, stone location, and as well as Hounsfield unit (HU) []. Gucuk et al. [] showed that the higher HU values increase the stone-free rate and HU is an independent predictive factor affecting the success of PNL. In the study by Huseynov et al., the higher HU may influence the stone-free rate of patients in primary PNL. Therefore, we thought that it must be mentioned in the discussion. Another issue that we have to be clear about is estimated blood loss and stone size. In addition to the decrease in hemoglobin level, the estimated blood loss during the surgery was analyzed but not mentioned how was calculated in the relevant section. Furthermore, calculation of stone size was also mentioned as it was multiplying two dimensions but in the result section, it was expressed the volume of stone in mm³ which means multiplying the three dimensions. For this reason, we are curious about your method of calculating the estimated blood loss during the operation and the technique of preoperative stone size calculation. As a result, we think that other factors including stone location in the kidney affects the success PNL. Hence, it should be examined in the study, otherwise, mentioned in the limitations of this study. Ethics Committee Approval: This article does not contain any studies with human participants performed by the author. Authorship Contributions: Any contribution was not made by any individual not listed as an author. Concept – E.S., M.K.; Design – E.S., M.K.; Supervision – E.S., M.K.; Resources – E.S., M.K.; Materials – E.S., M.K.; Data Collection and/or Processing – E.S., M.K.; Analysis and/or Interpretation – E.S., M.K.; Literature Search – E.S., M.K.; Writing – E.S., M.K.; Critical Review – E.S., M.K. Conflict of Interest: The author declares that he has no conflict of interest. Financial Disclosure: No grants or funding was provided for this study.