Ureterorenoscopic stone procedures have low success rates and poor post‐operative follow‐up: results from an Australian tertiary health service

To assess the results of ureterorenoscopy (URS) for upper tract urolithiasis in a contemporary Australian tertiary healthcare setting.


Introduction
Urolithasis is a condition which affects up to 15% of males and 8% of females during their lifetime. 1Whilst small intrarenal stones can be treated conservatively many renal stones will ultimately require some sort of intervention.
Treatment for renal tract stones depends on many factors including location, size and composition of the stone.Additionally, patients with secondary complications such as pyelonephritis or urosepsis may require urgent intervention.4][5] In Australia, URS procedures have increased by an average of 10% per year since 2001 while over the same period, rates of SWL and PCNL have decreased each year. 5uring URS, stone clearance can be attempted with laser fragmentation and basketing, laser 'dusting' (where high frequency, low energy settings are used to reduce the stone to a fine dust) or a combination of both.Stone free rates have been reported to be similar for all techniques however dusting may be associated with a significantly reduced operative time. 6he aim of any intervention for renal stones is stone clearance, which can only be adequately assessed with post-treatment imaging.The SWL literature has shown that small fragments can be left behind becoming a nidus for further stones. 7Recent studies have also suggested that many patients are undergoing expensive interventions with no attempt to review results 8 and the initial promising results following URS are not being maintained. 4his paper reviews the URS results from one of Australia's largest health service providers assessing post-op imaging and the results of surgery.

Methods
The hospital records of all ureterorenoscopic stone procedures performed between 1 January 2017 and 31 December 2018 at a large metropolitan Victoria Health Service were retrospectively reviewed.Case records were selected by querying the hospital activity database (iPM, the most widely used Patient Administrative System in Australia) for all ureterorenoscopic procedures performed in the operating theatres.Any cases that were performed for diagnostic purposes, for upper tract tumours or where no stones were dealt with were excluded.Information recorded from the patient record included: age, sex and body/mass index (BMI) of patient; size and position of stone; grade of operating surgeon and stone clearance; whether ureteric stents were used before or after the procedure; the type of energy used to deal with stones and whether items such as ureteric access sheaths and laser fibres were used during procedure; any complications or re-presentations to the health service emergency departments (ED); whether the patient was reviewed in the out-patients department; and whether any imaging was used to assess the success of the surgery.Stone clearance at the time of surgery was determined based on the results of intra-operative imaging, if conducted, and in cases with no intra-operative imaging, stone clearance was determined based on whether the operating surgeon thought the stone had been cleared.We do not think that selfdetermination regarding stone clearance at the time of surgery is accurate and wanted to compare this parameter to post-operative imaging.The most common imaging modalities used to assess stone clearance were CT and X-ray.Stone free was defined as no residual fragments on postoperative imaging.
As a check on the completeness of the data recorded from iPM, the senior authors prospectively collected database of procedures was analysed.The study had approval from the institution's Human Ethics and Research Committee (RES-19-0000-593Q).

Results
A total of 385 patients, 12 of whom had bilateral procedures (397 renal units), underwent 465 URS stone procedures (range 1-4) over the two-year period.342 of the 397 (86.1%) cases had a single URS.254 (64%) renal units were pre-stented and with post-URS stent removal a total of 1029 procedures were performed (range 1-5 procedures).Other demographic information is included in Table 1.
Details of the stone characteristics are reported in Table 2.The majority of stones (60.5%) were less than 10 mm in their maximum length, with 35.6% between 10 and 20 mm and a further 3.9% greater than 20 mm.
The main surgeon recorded was a trainee in 380 (81.7%) of the 465 procedures.Trainee levels ranged from SET 1-SET 6, with each having varying levels of consultant supervision.In 200 (52.6%) of the 380 trainee conducted procedures, the trainee was either in their final year or a Fellow and therefore less likely to be supervised.Peri-operative prophylactic antibiotics were recorded in all but 5/465 (1.1%) of cases.During the operation, access sheaths were used in 83% (386/465) of cases.Lasers were used in 83.7% (389/465) of cases, with no energy source used in 13.8% (64/465) and inadequate recording in the remainder (2.6%).When laser was used 60.4% (235/389) cases were recorded as fragmentation and 39.6% (154/389) 'dusting'.Laser time was not recorded in the patient record.226/465 (48.6%) of URS procedures were performed as day-cases with another 188 (40.4%) having an overnight stay.The remainder had stays ranging from 2 to 21 nights.
Imaging or surgeon reported stone clearance was 77.8% (309/397) whilst stone clearance was definitely not achieved in 18.9% (75/397).Inadequate information was present for 13 cases.Stone analysis was requested in 34.5% (137/397) renal units with calcium oxalate being the most common result.
Complications were recorded in 9% (42/465) of cases and are detailed in Table 3.All complications resulted in at least one overnight hospital stay.Clavien IIIa and Clavien IV complications occurred in patients with larger stone sizes (range 8-27 mm) and may have occurred as a result of longer operation time which is often seen with large renal stones.Representations to any of our own three ED occurred in 15.4% (61/397) of patients, mostly for stent symptoms or for delayed presentation of complications.This is almost certainly an underrepresentation as patients were based throughout the state and likely to present to their nearest ED without need for admission.
Post-operative review occurred in 49.1% (187/397) cases while post-operative imaging was recorded for 50.6% (201/397).Computerized tomography (CT) was utilized in 46.3% (93/201) with 40.3% (81/201) undergoing plain X-ray of the kidneys, ureter and bladder (KUB), 10.4% (21/201) having an ultrasound scan and in six cases the type of imaging was not recorded.When imaging was undertaken only 38.3% (77/201) of renal units were stone free.In the remaining 61.7% (124/201) residual fragments were recorded varying in size from 1 mm to over 10 mm.Details on the available stone free rates for initial stone sizes are recorded in Table 4.There was no statistically significant difference in the results when a consultant was main surgeon compared to a trainee.We identified 171 cases in which post-operative imaging was utilized while intra-operative imaging was not.In 129 (75.4%) of these cases, the surgeon believed that the stone was cleared, however on post-operative imaging of these cases only 57/129 (44.1%) were stone free.There were 30 cases in which both intra-operative and post-operative imaging was used to assess stone clearance and stone free status.Successful stone clearance was reported in 20/30 (66.6%) of these cases after intra-operative imaging however only 10/20 (50%) of these successful stone clearance cases remained stone free at post-operative imaging.

Discussion
The aim of treatment for renal tract stones should be stone clearance. 9It is well recognized that single procedures may not achieve stone clearance and the workup of any stone patient should include the advice that additional procedures/modalities may be required, or that small stone fragments may remain.
With advances in telescope design and laser technology, URS has become increasingly popular in Australia. 5,10There are varying reports on stone free rates following URS 3,4,6,11,12 often due to inconsistencies in reporting methods and differences in imaging used.Computed tomography is the best method to assess stone free status but there are concerns about the adverse cumulative effects of ionizing radiation with repeated scans, particularly in the young population that recurrent stone formers represent. 13his study reviews URS in a large Australian public, metropolitan, teaching health service.Over a thousand procedures, including stent insertions and removals, have been performed to treat less than 400 renal units, which is a significant impost on both the patients and the health service.Despite that, less than half of the patients had post-operative review and only just over half had any post-operative imaging.This is consistent with a recent report from the USA, 8 and the low number may be due to perceived success of the procedure at time of operation, improvement in patient symptoms post procedure and radiation associated with follow-up imaging.Of those patients who did have imaging, less than 40% of renal units were stone free, despite high rates of successful stone clearance reported by surgeons or evidenced by intra-operative imaging at time of surgery.Whilst the majority of the remaining stones were small they may become the nidus for further stone formation, 7 hence highlighting the need for post-operative review and imaging to ensure complete resolution of stones.The chronicity of renal stones is often underestimated and hence why follow-up may be overlooked in many patients leading to low levels of postoperative review and stone free rates.Retained fragments have been one of the historical criticisms of SWL treatment and probably one of the reasons for the enthusiastic uptake of URS.The results of this study are no better than SWL and are consistent with other recently published studies. 6Disappointingly the failure of stone clearance is apparent across all stone sizes when results are available.
Ureterorenoscopy has become a standard operation for trainee urologists and the majority of procedures in this study were performed by trainees of varying expertise.Even when a consultant was recorded as the main surgeon, much of the operation may have been performed by a trainee.As such it is difficult to compare results of trainees and consultants, however this would be an interesting idea to further evaluate and would help identify whether greater consultant supervision or involvement during URS procedures could lead to improved outcomes.We have not assessed how the decision to offer URS was made, which may influence some of the results.Many patients in the Australian system are not seen by consultants and some operating lists do not have consultant supervision.In nearly 4% of the cases the stones were of such a size that PCNL should be the recommended treatment and many of the smaller stones may have been better served with SWL, which is readily available in the study health service (unlike many other Australian sites).URS may have been selected in these cases due to perceived greater stone free rates however our study has shown that this is not the case.
The complication rate of nearly 10% is concerning and whilst most of the complications were relatively minor they all required at least one additional night in hospital.This is consistent with a recent Australian study which found infective complications were present in 10.2% of cases post URS. 14 Sepsis was the most serious common complication, which is well recognized for urological procedures and may not be preventable.One of the more serious complications in this series (stroke with associated pyrexia) did not have peri-operative antibiotics recorded which is a major oversight.The representation rate to ED of at least 15% is consistent with other reports. 15he retrospective nature of this study prevents any review of the pre-operative decision making but the large number of cases allows a snapshot of current Australian practice regarding URS.It could be argued that the results of those patients not reviewed were much better and that an active decision was made not to arrange any review, but there is no evidence in the hospital records that such decisions were made.
From these results it can be seen that URS consumes many hospital resources, has a 10% complication rate and a stone-free rate of less than 40%, when reviewed.With urinary tract stones accounting for almost 10% of all urological related deaths in Australia, a number of which can be attributed to clinical management issues during URS, 16 we would suggest that all patients with renal tract stones should be discussed at a regular stone meeting to ensure consistency in treatment and adherence to guidelines.Furthermore, follow-up appointments with stone analysis and imaging should be made mandatory practice and incorporated into local guidelines to ensure that all patients have adequate followup to ensure complete resolution of disease.This has become standard practice in many health systems for cancer surgery 17 yet stone problems affect an increasing proportion of the population, are often in younger patients, have a major economic impact on those patients and, with the increasing use of disposable equipment (access sheaths, guidewires, laser fibres and even ureterorenscopes), can cost health services vast sums.We estimate that the disposable costs alone to our public hospital are in excess of A$1000/procedure.The recently published UK NICE guidelines suggest more use is made of primary SWL for stones less than 10 mm. 18URS could then be reserved for those cases that fail SWL which would be economically beneficial. 19Whether URS should be used for larger stones is outside the scope of this paper but there could be a case that such stones should only be dealt with by stone experts who have the necessary skills for complete stone clearance, be that with URS, PCNL or a combination of these technologies.

Conclusion
In a snapshot of current Australian public hospital practice, less than half of all patients following URS were reviewed despite undergoing expensive, time consuming surgery for a condition that is known to have a high recurrence rate.Stone-free rates were low with significant complications and representation rates.Renal tract stones should be treated using a team approach, with cases discussed amongst a team of surgeons to guide optimal management.This will not only lead to better patient outcomes, but also lead to most cost-effective management of the disease.Furthermore, greater consultant supervision and involvement in URS procedures will likely lead to improved stone free rates and better trainee performance.While often overlooked, stone surgery should be given the attention and resources equivalent to cancer surgery to improve results.

Table 1
Patient demographic details

Table 3
Details of post URS complications

Table 4
Stone free rates for different stone sizes