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Ureteroscopic treatment of urolithiasis has become safer and more effective in the modern era. With a rise in the incidence of bilateral urolithiasis, management dilemma of staged single-side ureteroscopy versus bilateral simultaneous ureteroscopy (BS-URS) is often debatable. This review evaluates the current evidence base for bilateral simultaneous ureteroscopic approach in the modern era.
A systematic review was conducted from 1990 to June 2016 including all English language articles reporting on outcomes of BS-URS for urolithiasis. Data was split into two periods: period 1: 2003–2012 and period 2: 2013–2016, and analysed using SPSS version 21. A total of 11 studies (491 patients) were identified from a literature search of 148 studies with mean age of 45 years and a male: female ratio of 2:1 and a mean operative time of 69 min (SD=±15). The initial and final stone-free rate (SFR) was 87 and 93%, respectively. Post-operative stents were placed in 89% of patients with a mean hospital stay of 1.6 days (SD=±0.5). Overall, there was a significant negative association between case volume (procedures per month) and complication rate (p=0.045). Mean hospital stay was significantly longer in period 1 (1.9 days, SD=±0.5) than period 2 (1.3 days, SD=±0.3) and complications were also significantly higher in period 1 (47%) compared to period 2 (12%) (p<0.001). There were six studies examining holmium laser (HL) lithotripsy and three examining pneumatic lithotripsy (PL). There were significantly more complications after PL than HL; however, their SFR was similar.
Our review shows that the complication rates and hospital stay are significantly reduced in the contemporary data suggesting an improving trend in outcomes following BS-URS. Simultaneous bilateral ureteroscopic treatment of urolithiasis is safe and effective in the modern era. Safety is increased in centers with increased number of procedures performed and with laser lithotripsy.
The evolution of sophisticated miniature ureteroscopes and holmium laser technology has significantly reduced morbidity associated with ureteroscopy (URS). Evidence from contemporary literature suggests complications between 2.4 and 8.6% with URS [1, 2]. Ureteroscopy is increasing becoming the approach of choice in complex endourological management [2–4, 5•]. Despite this, the management of bilateral urolithiasis is a subject of much contention and debate amongst endourologists worldwide. Staged single-side URS is often employed in preference to a bilateral simultaneous ureteroscopic (BS-URS) approach. The concerns over BS-URS are due to higher morbidity in comparison with a staged approach. However the potential benefits of BS-URS include single anesthetic session and potentially reduced cost associated with treatment. In an era of austerity these are important considerations while making surgical decisions [6–8]. A recent systematic review of seven studies evaluating BS-URS did report an overall stone-free rate (SFR) of 90% suggesting it was a feasible strategy. However, they did report an overall complication rate of nearly 50%, although majority of them were Clavien score≤II . In this updated review, we aim to evaluate the following:
The systematic review was performed according to the Cochrane Review and the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. The search strategy was conducted to find relevant studies from Ovid Medline without revisions (1996–July 2016), Cochrane Library (2016), CINAHL (1990–July 2016), Clinicaltrials.gov, Google Scholar and individual urologic journals.
Terms used included ‘bilateral’, ‘simultaneous’, ‘synchronous’, ‘ureteroscopy’, ‘ureterorenoscopy’, ‘calculi’, ‘stones’ and ‘urolithiasis’. Boolean operators (AND, OR) were used to refine the search.
The search was limited to English language articles between 1996 and July 2016. Authors of the included studies were contacted in the case of data not being available or clear. Level of evidence was assessed using the recommendations set out by the Centre for Evidence-Based Medicine .
The following variables were extracted from each study: year of publication, study period, number of patients/renal units included, operative time, initial and final SFR, lithotripsy fragmentation device, post-operative stent use, stone size (mm), cumulative stone diameter (CSD) (mm) and complications. Complications were graded using the Clavien Dindo classification  in all studies. Case volume was calculated as procedures per month during the study period as reported in the individual studies. For subanalysis, the data was divided into historical and contemporary studies by splitting the collated data into Period 1 (2003 to 2012 inclusive) and Period 2 (2013 to July 2016 inclusive) [22••].
Data was collated using Microsoft Excel (version 12.2.4) and analyzed using SPSS (version 21). Chi square test was used for dichotomous data and independent T test for continuous data.
Our literature search produced 148 titles of which 131 articles were excluded due to non-relevance based on the title and abstract (see Fig. 1). Six further papers were excluded upon reading the full manuscript leaving 11 papers, which were included in the study [11–21]. Most studies were retrospective in nature and were no randomization or control groups in these studies (see Table Table1).1). All studies reported on BS-URS and associated variables mentioned in the data extraction section.
The type of ureteroscope used varied in these studies. Five studies used semirigid ureteroscopes only [12–15, 17], two studies used flexible ureteroscopes only [16, 19] and the other four studies used a combination of semirigid and flexible ureteroscopes [11, 18, 20]. (see Table Table11).
Overall there were 491 patients included in the review. Ten studies reported on the male to female ratio, which overall had a moderate male preponderance (2:1). The overall mean age was 44.7 years (SD=±4.7 years). Stone size was reported in all but one study . Mean stone size across these studies was 15.3 mm (SD=±6.5 mm) (see Table Table22).
Overall six studies [11, 16, 18–21] treated bilateral renal stones, three studies treated renal stones with contralateral ureteric stones [11, 19, 20] and eight studies [11–15, 17, 19, 20] treated bilateral ureteric stones (see Tables 3 and and44).
There was variation in how ‘stone free’ status was defined amongst included studies. Four studies defined it as fragments <4 mm [17–19, 21]. Drake et al. , Huang et al.  and Gunlusoy et al.  defined stone free ≤2 mm, <1 mm and no stones, respectively. The rest did not specify how stone-free status was defined (see Table Table5).5). Imaging modality and the time duration between intervention and imaging is also demonstrated in Table Table55.
In this updated review, a BS-URS approach achieved an overall SFR and complication rate of 92 and 26%, respectively. The mean hospital stay was just under 2 days. Notably, hospital stay and complications are significantly reduced in the contemporary data (from 2013) when compared with historical cohorts (prior to 2013) [22••] (see Fig. 3). Furthermore, the complication rates reported in this review are nearly half those reported in the systematic review by Rai et al. [22••] This data suggest an improving trend of outcomes following BS-URS. Other factors that have significantly improved outcomes are higher case volume per surgeon and the use of holmium laser fragmentation. This is a clear reflection of evolving expertise, endoscopic laser technology and a wider variety of available technique and technology [23–30].
Hollenbeck et al.  compared staged URS with BS-URS for bilateral urolithiasis in a retrospective case series. They reported that BS-URS was aassociated with added morbidity; however, the cumulative risk with staged URS procedures (14% per procedure) was similar to BS-URS (29%). However, this data has to be viewed with caution owing to its historical nature. Contemporary data from this review suggests a more encouraging trend with regards to complications from BS-URS. There has been a general reluctance to take up bilateral simultaneous management of urolithiasis. In a prospective study, Shen et al.  compared single-staged simultaneous URS and PCNL with staged procedures. They demonstrated a SFR of 92.3% with a low complication rate (11.5%). No complications were graded higher than Clavien III. Additionally, they reported significant reductions in anaesthetic time, operative time, hospital stay and costs with a single-stage approach, thus demonstrating feasibility and potential benefits of single-session strategy. Furthermore, bilateral single-session strategy has been reported with percutaneous nephrolithotomy (PCNL) and shock wave lithotripsy (SWL). The reported SFR for PCNL and SWL when employing a bilateral single-session treatment ranged between 87–96% and 60–80% [26–30], respectively. Whilst the SFR rates between PCNL and URS are similar, they have a demonstrably higher SFR in comparison to SWL. However, the complication rates with BS-PCNL range between 17 and 36% [26, 27, 30], much higher than complication rates reported in more contemporary BS-URS cohorts (period 2, complication rate of 12%). BS-URS appears a more effective and safer strategy in comparison with its other counterparts.
Superior outcomes in high-volume centers and increasing caseload have been demonstrated procedures such as URS  and PCNL . This systematic review is the first study to corroborate this observation in the context of BS-URS. This review also demonstrated that complication rates were significantly lower in studies that employed holmium laser fragmentation. These results corroborates with finding of a previous study for impacted ureteric stones, which also revealed a higher SFR with laser lithotripsy .
Our review highlights the lack of high quality evidence on BS-URS in the management of urolithiasis, with all studies of evidence level three. With the arrival of new digital ureteroscopes, these outcomes are likely to improve further . The review raises the issue of standardization of study parameters in order to make appropriate comparisons. For example, the SFR definition varied from study to study, as did the modality of post-operative imaging and time between the intervention and imaging. Due to this lack of standardization, the authors recommend interpreting the data in this study with caution. Further prospective, multi-centred studies with standardized SFR, imaging modality and outcome parameters should be conducted in this field .
The complication rate and hospital stay for bilateral simultaneous ureteroscopy for urolithiasis are significantly reduced in contemporary studies compared to previous studies. Higher case volume and holmium laser lithotripsy are associated with fewer complications.
Robert M. Geraghty, Bhavan P. Rai and Patrick Jones each declare no potential conflicts of interest. Bhaskar K. Somani reports honoraria from Coloplast and travel expenses covered/reimbursed by Storz.
This article does not contain any studies with human or animal subjects performed by any of the authors.
This article is part of the Topical Collection on Kidney Diseases