Case Report: An occurrence of steinstrasse in retrograde intra renal surgery (RIRS) for large staghorn kidney stone: a difficult experience in managing surgical outcomes

Immediate removal of staghorn kidney stones is important to prevent life-threatening complications. With the advancement of endoscopic technology, retrograde intrarenal surgery (RIRS) is now an alternate treatment to the standard percutaneous nephrolithotomy (PCNL) for stones removal. However, when used to treat large stones (>3cm), RIRS can cause the formation steinstrasse (SS). Here, we present the case of a 68-year-old man with multiple stones in the collecting system of the right kidney after initial treatment with RIRS. After two years of multiple interventions, the SS was completely removed. To prevent this complication in patients, a detailed assessment of the stone (size, location) and renal anatomy should be completed before RIRS is performed.


Introduction
The term "staghorn" describes the configuration of large, branched renal stones that occupy the pelvis and extend to at least two renal calyces. Immediate removal of the stones is compulsory to prevent serious kidney injury and life-threatening sepsis 1 . According to the American Urological Association, percutaneous nephrolithotomy (PCNL) is the standard treatment for staghorn removal 2 . Recently, urologists have started using retrograde intrarenal surgery (RIRS) to treat large stones as it is less invasive and simpler than PCNL 3 . However, RIRS might cause the formation of steinstrasse (SS), especially in large stones (2-3 cm) cases, which requires a series of interventions. This multiple procedure approach to renal stone treatment can impact patient quality of life, especially when the stone is hard (> 1000 Hounsfield Units) 4,5 .
The aim of this study is to address the formation of SS and the impact of prolonged treatment on the patient's psychological health following the use of RIRS for large staghorn stone removal.

Case presentation
A 68-year-old man came to our hospital in April 2016 with multiple stones in the collecting system of his right kidney. He had been experiencing flank pain that was not influenced by body position for one month. He denied any treatment relating to the pain that he experienced in this period. He also denied having a family history of this symptom or ever having this symptom before. Physical examination revealed only right flank tenderness.
Computed tomography (CT) urography at the previous hospital showed a staghorn stone at the right inferior calyx with a size of 45.7 × 59.3 × 27.5 mm (stone hardness in Hounsfield unit was not available) with a grade 3 right-side hydronephrosis and left kidney cyst. (Figure 1). Post-RIRS imaging showed a double J (DJ) stent with multiple tiny stones from the right pelvio-calyces to vesicoureteral junction (Figure 2a).
A month later, when the patient came to our hospital for a second opinion, his kidney-ureter-bladder (KUB) imaging result had not changed (Figure 2b). Right ureteroscopy (URS), right nephrostomy, and right PCNL were performed and post-operative KUB imaging was conducted (Figure 3a). Another right URS was performed two weeks later, showing the remaining 8-mm stone at the ureter-pelvic junction (UPJ; Figure 3b).
Extracorporeal shock wave lithotripsy (ESWL) had been performed twice in June 2016, resulting in a decrease stone size to 6 mm. (Figure 3c). Another ESWL was performed the next month ( Figure 3d). In July 2016, the patient underwent a right laser URS followed by replacement of the DJ stent ( Figure 3e). Three months later, another ESWL was performed (Figure 3f). Shortly after, the remaining DJ stent was removed. KUB imaging still showed residual right nephrolithiasis. (Figure 3g). In 2017, the patient presented with significant depression that he attributed to the numerous procedures, and he decided to end the treatment for his remaining stone. He reported a lack of spirit throughout the day since the failure of the last ESWL procedure and had a feeling that this stone would never be adequately treated, and his constant need for pain medication would continue.
Almost two years later (January 2018), routine KUB imaging and CT urography showed no change in his right nephrolithiasis (Figure 3h, i). In June 2019, he was persuaded by his family

Amendments from Version 1
We have addressed each of the Reviewer's critiques point by point and incorporated appropriate revisions into the text of the manuscript. This includes revisions to the title, introduction, discussion and case presentation sections, with these changes reflected in the abstract. We have changed Figure 1, updated Table 1 and added references as suggested by the reviewer.  to re-try stone management and had the final RIRS at another hospital, with successful complete removal of the remaining stone (Figure 3j). In November 2019, he visited our hospital for DJ stent removal. Neither stone nor DJ stent were observed in his KUB imaging. The summary of the patient's history of illness is presented in Table 1.

Discussion
The management of nephrolithiasis has changed dramatically over time, shifting from open surgery to less-invasive procedures, such as PCNL and ESWL 6 . According to the American Urological Association and European Association of Urology guidelines, the standard treatment for staghorn stone removal is PCNL 2,5 . PCNL has a high stone-free rate (SFR), similar to that of an open surgery (93%). It also results in lower morbidity, shorter operative time, shorter hospital stays, and earlier back to work compared to open surgery. However, it can cause severe complications, such as renal trauma with severe uncontrollable bleeding 7,8 .
On the other hand, the development of flexible ureteroscopes allows for excellent visualization that makes RIRS a favourable procedure for most urologists. The possibility to use holmium lasers along with the ureteroscope, and lower cost compared to the other treatment methods, has made this procedure even more popular 9 . Initially, the use of RIRS is limited to patients who cannot undergo PCNL or ESWL due to several contraindications. However, with the development of technology, the usage of RIRS for large stone is now possible. Compared to PCNL, RIRS has a slightly lower SFR of 87% and also lower morbidity and complication rate of 2% 10 . In our case, use of RIRS instead of PCNL as the first treatment was due to the patient's preference for a less invasive method.
RIRS is a less-invasive procedure compare to PCNL. Complications may arise intra-or post-operatively in some cases but are usually minor and manageable. The common complications of RIRS include hemorrhage, intrapelvic hematoma, mucosal injury, ureteral perforation and avulsion, urinary tract infection, and sepsis 11 . In a study by Niwa et al., the most common complication associated with RIRS in treating staghorn stones was urinary tract infection (Clavien-Dindo II, 28.2%), followed by fever (7.7%), general malaise (2.6%), and malposition of a ureteral stent (2.6%) 12 .
In Indonesia, PCNL is still the first choice for treating large renal calculi according to Ikatan Ahli Urologi Indonesia (the Indonesian Urologist Association). However, the use of PCNL in Indonesia is still limited due to the lack of technology and expertise, particularly in remote areas 13 . The incidence of SS formation after RIRS is 20% among those with large renal stone, while hydronephrosis is also common 4 . The development of SS was also observed in the patient we have described, who was initially treated with RIRS. To address this complication, a scoring system was developed by Resorlu et al. that includes four indicators: a renal stone size >20 mm, lower pole stone with an infundibulum-pelvic angle <45°, a stone number in different calyces >1, and abnormal renal anatomy 14 . A greater score is associated with a lower SFR. This score can be calculated prior to RIRS.
Another efficacy parameter for RIRS is stone composition. According to a study by Xue et al., stones that are made of calcium oxalate dihydrate, uric acid, and magnesium ammonium phosphate show an excellent response to RIRS treatment 15 . Unfortunately, in the present case, the stone composition was not analyzed due to financial constraints.  In the previous hospital, the ureteral stent was placed after RIRS treatment. The necessity for routine stent insertion before or after RIRS to increase stone clearance remains unclear. The primary purpose of stent insertion is to prevent ureteral stricture, accelerate healing, and facilitate stone passing 16 . On the other hand, stent insertion increases the possibility of urinary tract infection, dysuria, pollakiuria, hematuria, and may require repeated cystoscopy in cases of stent migration and need for extraction 17 . Stent insertion before ESWL does not eliminate the need for intervention in the management of SS 18 . In cases like the one we have presented, considering the size and the position of the stone, ureteral stent placement before RIRS would be difficult and other options should be considered.
Urolithiasis is a painful chronic disease that has significantly impacts on a patient's quality of life. In addition to chronic pain, the acute pain of urolithiasis resulting from stone movement often causes fear of recurrence. Recent studies have suggested an association between the disease and anxiety and depression 19 . In the present study, our patient developed symptoms of depression during the second year of his treatment because he had to undergo multiple surgical procedures within a year to remove the SS. In addition, the patient had to endure the pain associated with recovery after each procedure, as well as the pain caused by the remaining stone. After receiving support from his family and reassurance by clinicians, the patient was finally convinced to continue with treatment for his remaining stones.
RIRS may be used in cases where open surgery and ESWL are risky or inadequate, such as in patients with obesity, bleeding disorders, musculoskeletal deformities, renoureteral malformations, and infundibular stenosis 16 .
This study was limited in that we did not know the hardness (Hounsfield units) of the patient's stone before he visited our clinic; therefore, we could not more precisely determine the cause of his previous treatment failure, as our characterization was based only on the size of the stone.

Conclusions
RIRS is not the preferred option for removal of large staghorn calculi due to low efficacy and other possible complications. However, it can be used in circumstances where open surgery or PCNL are not possible. Careful assessment is essential to determine whether the procedure will be beneficial and safe for the patient.

Data availability
All data underlying the result are available as part of the article and no additional source data are required.

Consent
Written informed consent for publication of their clinical details and/or clinical images was obtained from the patient/ parent/guardian/relative of the patient.

Version 1
04 May 2020 Reviewer Report https://doi.org/10.5256/f1000research.24773.r61757 © 2020 Ather H. This is an open access peer review report distributed under the terms of the Creative Commons , which permits unrestricted use, distribution, and reproduction in any medium, provided the original Attribution License work is properly cited.

Department of Surgery, Aga Khan University, Karachi, Pakistan
Steinstrasse is a legacy of SWL (Does ureteral stenting prior to shock wave lithotripsy influence the need for intervention in steinstrasse and related complications? (Ather , 2009 )) and RIRS for et al. larger stones is no different from performing SWL under endoscopy. The authors should discuss this point.
Conclusions are contrary to the case account. The conclusions should be that larger stones (Staghorn) would preferably not be treated by RIRS.
Few minor issues: In the abstract I don't agree with the word "compulsory" -a more preferable alternative would be "desirable" or "important" etc.
RIRS is not mentioned as a treatment option for large kidney stones.
Mention other complications of the use of RIRS besides steinstrasse for large renal stones.
The phrase "RIRS to remove a staghorn stone" in the abstract is not an appropriate reflection of the abilities of RIRS in that set up.
There are many grammatical errors that need attention.
The authors used the phrase "which led to depression in the patient after the use of RIRS for staghorn stone removal". This needs to be rephrased for clarity as to what the authors are implying. Are they saying prolonged treatment causes psychological issues, like depression? Please cite a reference.
In the case presentation, the authors write "multiple stones along his right urogenital system" -this needs to be rewritten for clarity. Stones were in the collecting system of the right kidney.
With the limited access to single section I disagree with the authors' interpretation of the CT. I see a Staghorn stone with a major component in the renal pelvis and branching calculi in lower and middle pole calyces. There is dilatation and obstruction with ballooning of the upper pole calyx due 1 middle pole calyces. There is dilatation and obstruction with ballooning of the upper pole calyx due obstruction of the infundibulum of the upper pole calyx. There is no cyst visible in these scans. ureteral stent (2.6%).
The phrase "RIRS to remove a staghorn stone" in the abstract is not an appropriate reflection of the abilities of RIRS in that set up.

Author response:
We have revised our abstract as it is not aligned with the insight of our case presentation that do not recommend the use of RIRS for large stones removal. Here is the revised version: Immediate removal of staghorn kidney stones is important to prevent life-threatening complications. With the advancement of endoscopic technology, retrograde intrarenal surgery (RIRS) is now an alternate treatment to the standard percutaneous nephrolithotomy (PCNL) for stones removal. However, when used to treat large stones (>3cm), RIRS can cause the formation steinstrasse (SS).
There are many grammatical errors that need attention.

Author response:
Thank you for addressing your concern. We have revised the grammatical error that we found.
The authors used the phrase "which led to depression in the patient after the use of RIRS for staghorn stone removal". This needs to be rephrased for clarity as to what the authors are implying. Are they saying prolonged treatment causes psychological issues, like depression? Please cite a reference.

Author response:
We have added some information to clarify this issue. Urolithiasis is a painful chronic disease that has significant impacts on a patient's quality of life. In addition to chronic pain, the acute pain of urolithiasis resulting from stone movement often causes fear of recurrence. Recent studies have suggested an association between the disease and anxiety and depression. In the present study, our patient developed symptoms of depression during the second year of his treatment because he had to undergo multiple surgical procedures within a year to remove the SS. In addition, the patient had to endure the pain associated with recovery after each procedure, as well as the pain caused by the remaining stones.
In the case presentation, the authors write "multiple stones along his right urogenital system" -this needs to be rewritten for clarity. Stones were in the collecting system of the right kidney.

Author response:
Thank you for your correction. We have updated the term accordingly.
With the limited access to a single section I disagree with the authors' interpretation of the CT. I see a Staghorn stone with a major component in the renal pelvis and branching calculi in lower and middle pole calyces. There is dilatation and obstruction with ballooning of the upper pole calyx due to obstruction of the infundibulum of the upper pole calyx. There is no cyst visible in these scans.

Author response:
Thank you for your concern. We have decided to change the picture: © 2020 Soebadi D. This is an open access peer review report distributed under the terms of the Creative Commons , which permits unrestricted use, distribution, and reproduction in any medium, provided the original Attribution License work is properly cited.

Doddy Soebadi
Department of Urology, Faculty of Medicine, Airlangga University, Surabaya, Indonesia