Abstract
Background
The insertion of a ureteral access sheath (UAS) is a frequent procedure during flexible ureteroscopy (fURS) to facilitate kidney stone treatment. The aim of this study was to investigate the influence of 12/14 French (F) UAS on fURS outcomes.
Methods
We performed a retrospective monocentric analysis of fURS procedures conducted at the Department of Urology (University Hospital Schleswig–Holstein, Lübeck, Germany) for kidney stone treatment via lithotripsy or basket stone retrieval between September 2013 and June 2017. Uni- and multivariate analyses were done with the help of RStudio (Version 1.0.136) software.
Results
In total, 283 consecutive fURS were analyzed. UAS was applied in 98 cases (34.63%). The insertion of UAS was preferred in cases with multiple kidney stones and larger median maximal stone diameter (p < 0.05). UAS usage correlated with elevated radiation exposure in seconds (94 vs. 61; p < 0.0001), prolonged operation time in minutes (99 vs. 66, p < 0.0001), length of hospital stay over 48 h (LOS, 22.49% vs. 10.81%; p = 0.015), more frequent postoperative systemic inflammatory response syndrome (SIRS, 13.27% vs. 4.32%; p = 0.013) and lower postoperative stone-free rates (60.20% vs. 78.92%; p = 0.0013). Moreover, we conducted uni- and multivariate subgroup analysis for cases with multiple kidney stones (≥ 2) and comparable stone burden; UAS was inserted in 48.3% of these cases (71/147). On multivariate logistic regression, UAS insertion was statistically associated with prolonged operation time in minutes (101 vs. 77; p = 0.004). No statistical differences regarding radiation exposure, stone-free rates, postoperative SIRS rates or LOS were noted between UAS and non-UAS patients with multiple kidney stones of similar size (p > 0.05).
Conclusions
12/14F UAS does not seem to improve overall outcomes in fURS for kidney stones. In patients with multiple kidney stones it may be associated with elevated operation time without a clear benefit in terms of improved stone-free status or reduced perioperative complication rate. Further prospective randomized studies to specify the indications for UAS usage are urgently needed.
Keywords: Flexible ureteroscopy, Ureteral access sheath, Kidney stones, Urolithiasis, Complications
Background
The insertion of a ureteral access sheath (UAS) is a frequent procedure during flexible ureteroscopy (fURS) for kidney stone treatment [1]. Decreased intrarenal pressure as well as better irrigation and visibility are the rationale for UAS usage, to provide more efficient, faster and safer stone retrieval [2–4]. However, the current scientific evidence delivers many dilemmas that should be contemplated by the endourologist before UAS insertion. Firstly, reduced intrarenal pressure provided by the UAS seems to not result in a lower risk of postoperative complications, as numerous groups have reported either no effect or even an elevated risk of postoperative complications associated with UAS usage [5–7]. Moreover, the direct impact of UAS on the improvement of stone-free rates is arguable, according to the available literature [8–10]. The guidelines of the European Association of Urology (EAU) give no recommendation on UAS usage, whereas the American Urological Association advocates for UAS usage for cases with a complex stone burden [11, 12]. Based on the aforementioned scientific background, the aim of our study was to retrospectively investigate the influence of 12/14 French (F) UAS on fURS outcomes at our department and to discuss the future directions for research on UAS.
Methods
A retrospective monocentric analysis of fURS procedures was performed, conducted at the Department of Urology (University Hospital Schleswig–Holstein, Lübeck, Germany) for kidney stone treatment via lithotripsy or basket stone retrieval between September 2013 and June 2017.
The details of the fURS procedure have already been described in our previous manuscripts [13, 14]. The patients consented to fURS at least 24 h preoperatively. Urine culture was gathered less than 14 days before the surgery. In cases with positive preoperative urine culture, antibiotic therapy was begun, usually at least 2 days preoperatively. Antibiotic prophylaxis was defined as a preoperative or intraoperative administration of antibiotics in cases with negative preoperative urine culture. Antibiotic prophylaxis was applied dependent on the decision of the endourologist. All fURS procedures were conducted in a supine lithotomy position. The surgeries were performed with reusable flexible ureteroscopes: digital Olympus URF-V or fiberoptic Karl Storz Flex-X2. fURS in our department is usually preceded by semirigid ureteroscopy (URS). Prior to the use of fURS, contrast (Urolux Retro®, CS Diagnostics GmbH) was injected into the proximal ureter via semirigid ureteroscope to present the pyelocalyceal anatomy. Ureteral access sheath (Olympus UroPass; 12/14F) insertion was not a standard in every fURS procedure. The decision was based on the preference of the surgeon, which depended mostly on the extent of the stone burden.
Holmium laserlithotripsy (Lumenis VersaPulse® PowerSuite™ 100 W) was performed with a reusable SlimLine™ 200 μm fiber (Boston Scientific). Total laser energy was defined as the cumulative lithotripsy energy via the semirigid and flexible ureteroscope. Calculi extraction during fURS was conducted with Stonizer® tipless (1.9F, Uromed) or NGage® (2.2F, Cook Medical) nitinol baskets. A ureteral double-J stent was reinserted depending on the complexity of fURS and significance of ureteral lesions.
Stone-free status (SFS) was determined intraoperatively by the endourologist with the assistance of intraoperative fluoroscopy. Radiological postoperative re-evaluation with computed tomography (CT) or delayed kidney, ureter and bladder (KUB) radiography was always performed in case of uncertainty regarding SFS. The length of hospital stay (LOS) for a routine postoperative course was limited to 48 postoperative hours. Every patient with at least one stone episode in the past was categorized as a recurrent stone former.
The determination of the infundibulopelvic angle (IPA) was based on preoperative native CT images in the coronal plane and intraoperative retrograde pyelography (RPG) images. The IPA was measured in accordance with the El-Bahnasy definition, as the angle between the ureteropelvic axis and the central axis of the lower pole of the infundibulum [15]. CT-based IPA was measured only in patients with a reliable outline of the proximal ureter and lower calyx on coronal CT images.
Intra- and postoperative complications were classified according to the Clavien-Dindo scale [16]. Following the definition of systemic inflammatory response syndrome (SIRS), at least two out of four criteria (body temperature < 36 °C or > 38 °C, heart rate > 90 bpm, respiratory rate > 20 per minute, WBC < 4000 or > 12,000 cells/mm3) were fulfilled in patients assigned to postoperative SIRS group [17].
Uni- and multivariate analyses were conducted with the help of RStudio (Version 1.0.136) software. The descriptive statistics comprise the mean value with standard deviation (SD) for normally distributed data, the median value with interquartile range (IQR) for data without a normal distribution, and percent values for categorical data. The chi2 test was applied for categorical data whenever applicable. The normal distribution of quantitative data was tested with the Shapiro–Wilk test. Student’s t-test was conducted for univariate analysis of the variables with a normal distribution. The parameters without a normal distribution were analyzed with the Mann Whitney-U test (MWU). The level of significance was p < 0.05. The present study obtained approval from the ethical committee of the University of Lübeck.
Results
In total, 283 consecutive fURS for stone surgery performed between September 2013 and June 2017 were analyzed. 12/14F UAS was applied in 98 cases (34.63%). On univariate analysis, the insertion of 12/14F UAS was preferred in cases with multiple kidney stones [UAS: 71/98 (72.45%) vs. non-UAS: 76/185 (41.08%); p < 0.0001] and larger median maximal stone diameter [UAS: 7 mm (IQR 5; 10) vs. non-UAS: 6 mm (IQR 4; 9); p = 0.042]. Detailed results of univariate testing are presented in Table 1. Multivariate binary logistic regression confirmed the overall statistical correlation of 12/14F UAS usage with elevated radiation exposure [UAS: 94 s (IQR 67; 142) vs. non-UAS: 61 s (IQR 33; 100); p < 0.0001], prolonged operation time [UAS: 99 min (IQR 76; 121) vs. non-UAS: 66 min (IQR 46; 91), p < 0.0001], length of hospital stay [LOS > 48 h; UAS: 22/98 (22.49%) vs. non-UAS: 20/185 (10.81%); p = 0.015], more frequent postoperative SIRS [UAS: 13/98 (13.27%) vs. non-UAS: 8/185 (4.32%); p = 0.013] and lower rate of postoperative SFS [UAS: 59/98 (60.20%) vs. non-UAS: 146/185 (78.92%); p = 0.0013]. Reported relevant complications were defined as at least Clavien-Dindo Grade 2 (CD ≥ 2) events. In the UAS group, these included one intraoperative bleeding with postoperative SIRS, one ureteral perforation with postoperative SIRS, and eleven postoperative SIRS without intraoperative complications. In the non-UAS group, we recorded two intraoperative perforations of the calyceal system, one ureteral perforation, eight postoperative SIRS without intraoperative complications, one relevant postoperative gross hematuria, and one aspiration pneumonia.
Table 1.
Overall univariate analysis of 12/14F ureteral access sheath (UAS) usage
| Total | UAS | No UAS | p value | Test | ||
|---|---|---|---|---|---|---|
| General characteristics | Number of cases | 283 | 98 | 185 | ||
| Gender (male/female) | 194/89 | 62/36 | 132/53 | 0.2079 | Chi2 | |
| Side (Right/Left) | 124/283 (43.82%) | 43/98 (43.88%) | 81/185 (43.78%) | 1 | Chi2 | |
| Median Age (IQR), years | 56 (42; 68) | 54 (38; 68) | 58 (45; 68) | 0.3604 | MWU | |
| BMI (IQR) | 27 (25; 31) | 27 (25; 30) | 27 (24; 31) | 0.9827 | MWU | |
| ASA > 2* | 54/262 (20.61%) | 23/91 (25.27%) | 31/171 (18.12%) | 0.2297 | Chi2 | |
| Recurrent Stone Former | 119/283 (42.05%) | 50/98 (51.02%) | 69/185 (37.30%) | 0.0359 | Chi2 | |
| Prestenting | 268/283 (94.70%) | 96/98 (97.96%) | 172/185 (92.97%) | 0.1330 | Chi2 | |
| Positive preoperative urine culture** | 81/259 (31.27%) | 42/90 (46.67%) | 39/169 (23.08%) | 0.0002 | Chi2 | |
| Antibiotic prophylaxis*** | 64/177 (83.12%) | 24/48 (50.00%) | 40/129 (31.01%) | 0.0306 | Chi2 | |
| Stone characteristics | Concomitant Ureterolithiasis | 82/283 (28.96%) | 28/98 (28.57%) | 54/185 (29.19%) | 1 | Chi2 |
| Lower Pole Kidney Stone | 213/283 (75.27%) | 82/98 (83.67%) | 131/185 (70.81%) | 0.0250 | Chi2 | |
| Median Lower Pole Kidney Stone Diameter (IQR), mm | 6 (4; 8) | 6 (4; 9) | 5 (5; 8) | 0.4678 | MWU | |
| Median Kidney Stone Max. Diameter (IQR), mm | 6 (5; 9) | 7 (5; 10) | 6 (4; 9) | 0.0420 | MWU | |
| Multiple Kidney Stones (≥ 2) | 147/283 (51.94%) | 71/98 (72.45%) | 76/185 (41.08%) | < 0.0001 | Chi2 | |
| Median HU (IQR) | 900 (60; 1034) | 900 (550; 1000) | 900 (600; 1036) | 0.3566 | MWU | |
| Operative characteristics | Median IPA (SD), degrees | 54 (42; 64) | 52 (40; 60) | 56 (43; 66) | 0.0497 | MWU |
| Median IPA – preoperative imaging (IQR), degrees | 51 (40; 64) | 44 (37; 60) | 52 (41; 66) | 0.0661 | MWU | |
| Safety Wire**** | 220/274 (80.59%) | 73/95 (76.84%) | 147/178 (82.58%) | 0.3261 | Chi2 | |
| Preceding semirigid URS | 198/283 (69.96%) | 63/98 (64.29%) | 135/185 (72.97%) | 0.1674 | Chi2 | |
| Stone Extraction with fURS | 263/283 (92.93%) | 94/98 (95.92%) | 169/185 (91.35%) | 0.2370 | Chi2 | |
| Postoperative Stenting | 271/283 (95.76%) | 98/98 (100.00%) | 173/185 (93.51%) | 0.0234 | Chi2 | |
| Median Fluoroscopy Time**** (IQR), s | 72 (44; 120) | 94 (67; 142) | 61 (33; 100) | < 0.0001 | MWU | |
| Median Operation Time (IQR), min | 77 (51; 105) | 99 (76; 121) | 66 (46; 91) | < 0.0001 | MWU | |
| Laser in Calyceal System | 170/283 (60.07%) | 63/98 (64.29%) | 107/185 (57.84%) | 0.2920 | Chi2 | |
| Median Total Laser Energy (IQR), kJ | 1.19 (0.39; 2.33) | 1.22 (0.42; 2.41) | 1.16 (0.39; 2.27) | 0.4177 | MWU | |
| Outcomes | LOS > 48 h | 42/283 (14.84%) | 22/98 (22.49%) | 20/185 (10.81%) | 0.0145 | Chi2 |
| fURS Defect | 29/283 (10.25%) | 13/98 (13.27%) | 16/185 (8.65%) | 0.3113 | Chi2 | |
| Clavien Dindo ≥ 2 | 26/283 (9.19%) | 13/98 (13.27%) | 13/185 (7.03%) | 0.1304 | Chi2 | |
| Postoperative SIRS | 21/185 (11.35%) | 13/98 (13.27%) | 8/185 (4.32%) | 0.0127 | Chi2 | |
| Stone-free status | 205/283 (72.44%) | 59/98 (60.20%) | 146/185 (78.92%) | 0.0013 | Chi2 |
ASA—American Society of Anaesthesiology scale; fURS—flexible ureteroscopy; HU—Hounsfield units; IPA—infundibulopelvic angle; IQR—interquartile range; LOS—length of hospital stay; MWU—Mann Whitney-U test; SIRS—systemic inflammatory response syndrome; URS- ureteroscopy
*No data in 21 cases
**No data in 24 cases
***Only cases with negative preoperative urine culture included. No data in 1 case
****No data in 10 cases
In order to reduce bias due to heterogenic cohorts demonstrated in aforementioned overall analysis, we conducted uni- and multivariate subgroup analysis for cases with multiple kidney stones (≥ 2) that are primarily considered for 12/14F UAS usage in our department. In this subanalysis stone characteristics were comparable between the cohorts. 12/14F UAS was inserted in 48.3% of cases (71/147), irrespective of median maximal stone diameter, median stone density, presence and size of lower pole stones (p > 0.05). Full results of the univariate testing for this subgroup are presented in Table 2. On multivariate logistic regression, 12/14F UAS insertion was statistically associated in the analyzed subgroup with prolonged operation time [UAS: 101 min (IQR 76; 128) vs. non-UAS: 77 min (IQR 54; 104); p = 0.004]. No differences regarding radiation exposure, SFR, postoperative SIRS rates and LOS were noted between UAS and non-UAS cases with multiple kidney stones of similar size (p > 0.05). The results of the multivariate binary logistic regression for this subgroup are presented in Table 3.
Table 2.
Univariate analysis of UAS usage in patients with multiple kidney stones (≥ 2)
| Total | UAS | No UAS | p value | Test | ||
|---|---|---|---|---|---|---|
| General characteristics | Number of cases with multiple kidney stones (≥ 2) | 147 | 71 | 76 | ||
| Gender (male/female) | 100/47 | 45/26 | 55/21 | 0.3218 | Chi2 | |
| Side (Right/Left) | 58/89 | 31/40 | 27/49 | 0.4011 | Chi2 | |
| Median Age (IQR), years | 56 (41; 70) | 56 (39; 69) | 55 (45; 70) | 0.3199 | MWU | |
| BMI (IQR) | 26 (24; 30) | 26 (24; 30) | 27 (24; 30) | 0.5150 | MWU | |
| ASA > 2* | 30/136 (22.06%) | 17/64 (26.56%) | 13/72 (18.06%) | 0.3236 | Chi2 | |
| Recurrent Stone Former | 74/147 (50.34%) | 40/71 (56.34%) | 34/76 (44.74%) | 0.2147 | Chi2 | |
| Prestenting | 138/147 (93.88%) | 70/71 (98.59%) | 68/76 (89.47%) | 0.0500 | Chi2 | |
| Positive preoperative urine culture** | 47/130 (36.15%) | 29/65 (44.61%) | 18/65 (27.69%) | 0.0679 | Chi2 | |
| Antibiotic prophylaxis*** | 44/83 (53.01%) | 23/36 (63.89%) | 21/47 (44.68%) | 0.1296 | Chi2 | |
| Stone characteristics | Concomitant Ureterolithiasis | 45/147 (30.61%) | 25/71 (35.21%) | 20/76 (26.32%) | 0.3220 | Chi2 |
| Lower Pole Kidney Stone | 129/147 (87.76%) | 62/71 (87.32%) | 67/76 (88.16%) | 1 | Chi2 | |
| Median Lower Pole Kidney Stone Diameter (IQR), mm | 5 (4; 8) | 5 (4; 8) | 6 (4; 8) | 0.8806 | MWU | |
| Median Kidney Stone Max. Diameter (IQR), mm | 7 (5; 9) | 7 (5; 9) | 6 (5; 9) | 0.8928 | MWU | |
| Mean HU (SD) | 855 (483) | 811 (459) | 905 (506) | 0.1502 | t-test | |
| Operative characteristics | Mean IPA (SD), degrees | 52.62 (17.26) | 50.14 (17.13) | 54.91 (17.06) | 0.08612 | t-test |
| Median IPA – preoperative imaging (IQR), degrees | 49 (41; 65) | 44 (40; 60) | 54 (43; 66) | 0.07342 | MWU | |
| Safety Wire**** | 114/143 (79.72%) | 53/69 (76.81%) | 61/74 (82.43%) | 0.5305 | Chi2 | |
| Preceding semirigid URS | 96/147 (65.31%) | 44/71 (61.97%) | 52/76 (68.42%) | 0.5173 | Chi2 | |
| Stone Extraction with fURS | 139/147 (94.56%) | 70/71 (98.59%) | 69/76 (90.79%) | 0.08543 | Chi2 | |
| Postoperative Stenting | 143/147 (97.29%) | 71/71 (100.00%) | 72/76 (94.74%) | 0.1463 | Chi2 | |
| Median Fluoroscopy Time**** (IQR), s | 85 (54; 139) | 101 (65; 140) | 71 (41; 128) | 0.0188 | MWU | |
| Median Operation Time (IQR), min | 92 (58; 118) | 101 (76; 128) | 77 (54; 104) | 0.0041 | MWU | |
| Laser in Calyceal System | 97/147 (65.99%) | 43/71 (60.56%) | 54/76 (71.05%) | 0.2431 | Chi2 | |
| Median Total Laser Energy (IQR), kJ | 1.24 (0.54; 2.41) | 1.27 (0.88; 2.41) | 1.04 (0.48; 2.35) | 0.2599 | MWU | |
| Outcomes | LOS > 48 h | 28/147 (19.05%) | 17/71 (23.94%) | 11/76 (14.47%) | 0.2109 | Chi2 |
| fURS Defect | 18/147 (12.24%) | 11/71 (15.49%) | 7/76 (9.21%) | 0.3631 | Chi2 | |
| Clavien Dindo ≥ 2 | 16/147 (10.88%) | 10/71 (14.08%) | 6/76 (7.89%) | 0.3477 | Chi2 | |
| Postoperative SIRS | 13/147 (8.84%) | 10/71 (14.08%) | 3/76 (3.95%) | 0.0611 | Chi2 | |
| Stone-free status | 95/147 (64.63%) | 42/71 (59.15%) | 53/76 (69.74%) | 0.2427 | Chi2 |
ASA—American Society of Anaesthesiology scale; fURS—flexible ureteroscopy; HU—Hounsfield units; IPA – infundibulopelvic angle; IQR—interquartile range; LOS—length of hospital stay; MWU—Mann Whitney-U test; SIRS—systemic inflammatory response syndrome; URS- ureteroscopy
*No data in 11 cases
**No data in 17 cases
***Only cases with negative preoperative urine culture included
****No data in 4 cases
Table 3.
Binary logistic regression of UAS usage in patients with multiple kidney stones (≥ 2)
| Odds ratio | 95% confidence interval | p value | |
|---|---|---|---|
| Positive preoperative urine culture** | 1.2113 | 0.4748–3.0927 | 0.6861 |
| Lower pole kidney stone diameter | 0.9856 | 0.7718–1.2685 | 0.9077 |
| Kidney stone max. diameter | 0.9602 | 0.7393–1.2222 | 0.7474 |
| Fluoroscopy time**** | 0.9948 | 0.9869–1.0009 | 0.1382 |
| Operation time | 1.0230 | 1.0100–1.0379 | 0.0009 |
| LOS > 48 h | 3.3989 | 0.8420–15.0767 | 0.0911 |
| fURS defect | 4.6702 | 0.9356–35.8181 | 0.0860 |
| Postoperative SIRS | 0.3997 | 0.0397–4.6656 | 0.4365 |
| Stone-free status | 0.5909 | 0.1793–1.8851 | 0.3754 |
fURS—flexible ureteroscopy; LOS—length of hospital stay; SIRS—systemic inflammatory response syndrome
**No data in 17 cases
****No data in 4 cases
Discussion
Our study presents the retrospective outcomes of 12/14F UAS usage during fURS. Overall analysis as well as subanalysis for multiple stones of similar burden confirmed no clear benefit of 12/14F UAS. Due to the heterogeneity of stone characteristics demonstrated in overall analysis we suggest a special focus on the subgroup analysis of statistically comparable cases with multiple kidney stones (≥ 2) and similar stone size.
The reduction of bacterial backflow to the venous system due to lowered intrarenal pressure during ureteroscopy has been proposed as a rationale for UAS usage in sepsis prevention [18, 19]. Adversely, we recorded a trend towards the development of SIRS in overall analysis of the patients operated on with the help of 12/14F UAS. Uneven rate of positive preoperative urine cultures between the groups has to be seen as a negative consequence of the retrospective character of the study. The trend towards perioperative SIRS in UAS patients was rejected by subanalysis for multiple calculi cohort, where general and stone characteristics as well as microbiologic urine status between the UAS and non-UAS groups where statistically comparable. However, a protective role of UAS usage regarding SIRS could not be confirmed.
Moreover, we were unable to prove the benefit of 12/14F UAS usage on SFS, fluoroscopy and operating time neither in the overall cohort, nor in subgroup analysis of cases with multiple calculi.
The analyzed cases operated with UAS were correlated in uni- and multivariate analysis with a prolonged operating time. We should discuss the possible reasons of these unexpected results. A relevant percentage (ca. 40%) of fURS is being performed at our department by residents in training [14]. fURS with UAS is in our opinion more challenging due to insertion-related issues, less intuitive orientation in calyceal system in a low-pressure environment and continuous attention to a correct position of UAS during repeated stone extractions. These factors, encountered especially by less experienced surgeons, could result in prolonged operative time of UAS group.
The presented results put into question the rationale for 12/14F UAS usage, but however should be cautiously discussed, taking into consideration the limitations of the study. Firstly, the usage of UAS was allowed in every case, depended on subjective surgeon preference. Despite the similar parameters characterizing both groups (UAS and non-UAS) with multiple calculi, we are aware that endourologists at our department tend to use UAS in patients with a more demanding anatomy or stone burden. Easier cases, even with multiple kidney stones, are often treated by fURS without UAS usage. This must be considered as a bias, diminishing the accuracy of the presented comparison.
Secondly, we acknowledge some deficits in gathered data due to the retrospective design of our study. The surgeries were performed mostly as “basketing” fURS for smaller stones without the need of lithotripsy, or “dusting plus basketing” versus “dusting plus active hand irrigation” fURS for larger stone burden. The exact type of the stone removal following the lithotripsy ( “dusting plus basketing” vs. “dusting plus active hand irrigation”) was not recorded in the study; hence our retrospective analysis does not provide data regarding how many UAS cases were conducted with active calyceal irrigation with a manual syringe pump. In our practice, some unexperienced surgeons may tend to irrigate more vigorously during fURS to obtain a clear view, which may possibly lead to infectious complications. Here UAS size plays a crucial role in lowering the pressure, especially during active irrigation, which may provide benefit especially in terms of preventing SIRS development. Noureldin et al. showed in a porcine in vivo model that 12/14 F UAS provided a sufficient, 12-fold reduction in intrarenal pressure during fURS with gravity irrigation, but only a fivefold reduction under active pump irrigation [4]. The best possible pressure reduction was obtained solely by 14/16F UAS – 1 cmH2O both under passive and active irrigation.
Thirdly, we were unable to record the detailed status of intraoperative ureteral lesions during fURS. The rate of ureteral perforations was low (one case for the UAS group and one case for the non-UAS group). The high rates of postoperative stenting in the analyzed cohort have to be interpreted as a preventive measure. Placement of a mono-J catheter or double-J catheter on the string should be discussed as an alternative for postoperatively stone-free patients to spare them additional cystoscopy for double-J stent extraction [20].
Despite the mentioned drawbacks, mostly due to the retrospective character, our study enriches the limited and ambiguous evidence on UAS application. Only one randomized controlled trial has been conducted so far on UAS insertion for kidney stone treatment. Kourambas et al. found no influence of 12/14F UAS usage regarding SFS and complications, but UAS application allowed for a significant reduction in operating time [21].
Traxer et al. confirmed in a multicentric prospective non-randomized study on a large number (2,239) of cases no influence of UAS on SFS as well as parallel significant reduction of infectious complications [8]. No subgroup analysis of different UAS sizes, as well as the non-randomized character of the study should be mentioned as the limitations of this study.
One of the few studies demonstrating an actual advantage of UAS usage in terms of higher rates of SFS was published by L’esperance et al. [9]. The authors presented retrospective results, where UAS application statistically improved SFS (79% vs. 67%, p = 0.042).
The literature describing differences between various UAS sizes is scarce. A broad majority of the cited publications analyzed the application of universal 12/14F UAS. 12/14F UAS is considered an “all-rounder”, eligible both for a stented and non-stented ureter [22]. Taking into consideration the extremely rare 12/14F UAS insertion-related complications in our study, further studies focusing on the outcomes of the larger 14/16F UAS are warranted in our opinion. The insertion of 14/16F UAS in patients may result in better stone removal and a reduction in intrarenal pressure and associated SIRS. We advocate for a prospective randomized trial of different sizes of UAS, standardized regarding the experience status of the surgeons, to reliably investigate the general benefit of UAS and to determine the specific indications for a given UAS size, taking into consideration the possible complications of UAS associated with mechanical traction and overstretching of the ureter [23, 24].
Conclusion
Based on our retrospective results, the usage of 12/14F UAS does not seem to improve outcomes in fURS for kidney stones. In patients with multiple kidney stones it may be associated with elevated operation time without a clear benefit in terms of improved SFS or reduced perioperative complication rate. However, relevant limitations of retrospective study design have to be considered. Prospective randomized studies are urgently needed to define the conditions of effective, safe and cost-effective UAS usage.
Acknowledgements
Not applicable.
Abbreviations
- ASA
American society of anaesthesiology scale
- CD
Clavien-Dindo
- CT
Computed tomography
- EAU
European association of urology
- F
French
- fURS
Flexible ureteroscopy
- HU
Hounsfield units
- IQR
Interquartile range
- KUB
Kidney, ureter and bladder radiography
- LOS
Length of hospital stay
- MWU
Mann Whitney-U test
- RPG
Retrograde pyelography
- SD
Standard deviation
- SFS
Stone-free status
- SIRS
Systemic inflammatory response syndrome
- UAS
Ureteral access sheath
- URS
ureteroscopy
Author contributions
TO contributed to project development, statistics, manuscript writing/editing. JRW, JPS, MCR, NG, JML contributed to data collection, manuscript writing/editing, project development. NG, JML contributed to project development. ASM, MWK contributed to manuscript writing/editing, project development. All authors read and approved the final manuscript.
Funding
Open Access funding enabled and organized by Projekt DEAL. No funding was received.
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethical approval and consent to participate
All methods were carried out in accordance with Helsinki declaration. Ethical committee approval (Ethics Committee of University of Lübeck; No. 18–251) was obtained for this retrospective study. Due to the retrospective character of the study additional informed consent was waived by the Ethics Committee of University of Lübeck.
Consent for publication
Not obtained, due to retrospective character of the study.
Competing interests
The authors declare that they have no conflict of interest.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Contributor Information
Tomasz Ozimek, Email: tomasz.ozimek@uksh.de.
Judith R. Wiessmeyer, Email: riccarda.wiessmeyer@uksh.de
Julian P. Struck, Email: julian.struck@uksh.de
Marie C. Roesch, Email: mariechristine.roesch@uksh.de
Nils Gilbert, Email: nils.gilbert@uksh.de.
Jan M. Laturnus, Email: jan.laturnus@uksh.de
Axel S. Merseburger, Email: axel.merseburger@uksh.de
Mario W. Kramer, Email: mario.kramer@uksh.de
References
- 1.Zilberman DE, Lazarovich A, Winkler H, Kleinmann N. Practice patterns of ureteral access sheath during ureteroscopy for nephrolithiasis: a survey among endourologists worldwide. BMC Urol. 2019;19:58. doi: 10.1186/s12894-019-0489-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.MacCraith E, Yap LC, Elamin M et al. Evaluation of the impact of ureteroscope, Access Sheath, and Irrigation System Selection on Intrarenal Pressures in a Porcine Kidney Model. J Endourol. 2020; Epub ahead of print. [DOI] [PubMed]
- 3.Rehman J, Monga M, Landman J, et al. Characterization of intrapelvic pressure during ureteropyeloscopy with ureteral access sheaths. Urology. 2003;61:713–718. doi: 10.1016/S0090-4295(02)02440-8. [DOI] [PubMed] [Google Scholar]
- 4.Noureldin YA, Kallidonis P, Ntasiotis P, et al. The effect of irrigation power and ureteral access sheath diameter on the maximal intra-pelvic pressure during ureteroscopy: in vivo experimental study in a live anesthetized pig. J Endourol. 2019;33(9):725–729. doi: 10.1089/end.2019.0317. [DOI] [PubMed] [Google Scholar]
- 5.Meier K, Hiller S, Dauw CA et al. Understanding ureteral access sheath use within a statewide collaborative and its effect on surgical and clinical outcomes. J Endourol. 2021; Epub ahead of print. [DOI] [PubMed]
- 6.Geraghty RM, Ishii H, Somani BK. Outcomes of flexible ureteroscopy and laser fragmentation for treatment of large renal stones with and without the use of ureteral access sheaths: results from a university hospital with a review of literature. Scand J Urol. 2016;50(3):216–219. doi: 10.3109/21681805.2015.1121407. [DOI] [PubMed] [Google Scholar]
- 7.Huang J, Zhao Z, AlSmadi JK, et al. Use of the ureteral access sheath during ureteroscopy: a systematic review and meta-analysis. PLoS ONE. 2018;13(2):e0193600. doi: 10.1371/journal.pone.0193600. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Traxer O, Wendt-Nordahl G, Sodha H, et al. Differences in renal stone treatment and out- comes for patients treated either with or without the support of a ureteral access sheath: the clinical research office of the endourological society ureteroscopy global study. World J Urol. 2015;33:2137–2144. doi: 10.1007/s00345-015-1582-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.L'esperance JO, Ekeruo WO, Scales CD, Jr, et al. Effect of ureteral access sheath on stone-free rates in patients undergoing ureteroscopic management of renal calculi. Urology. 2005;66:252–255. doi: 10.1016/j.urology.2005.03.019. [DOI] [PubMed] [Google Scholar]
- 10.Berquet G, Prunel P, Verhoest G, et al. The use of a ureteral access sheath does not improve stone-free rate after ureteroscopy for upper urinary tract stones. World J Urol. 2014;32(1):229–232. doi: 10.1007/s00345-013-1181-5. [DOI] [PubMed] [Google Scholar]
- 11.Türk C, Petřík A, Sarica K, et al. EAU guidelines on interventional treatment for urolithiasis. Eur Urol. 2016;69:475–482. doi: 10.1016/j.eururo.2015.07.041. [DOI] [PubMed] [Google Scholar]
- 12.Assimos D, Krambeck A, Miller NL, et al. Surgical management of stones: American urological association/endourological society guideline, part I. J Urol. 2016;196:1153–1160. doi: 10.1016/j.juro.2016.05.090. [DOI] [PubMed] [Google Scholar]
- 13.Ozimek T, Cordes J, Gilbert N, et al. Laser fibre, rather than the stone, may harm the scope: retrospective monocentric analysis of 26 pre- and intraoperative factors of flexible ureteroscope (fURS) damage. World J Urol. 2020;38(8):2035–2040. doi: 10.1007/s00345-019-02988-0. [DOI] [PubMed] [Google Scholar]
- 14.Ozimek T, Kramer MW, Hupe MC, et al. The impact of endourological experience on flexible ureteroscopy outcomes and performance at different levels of expertise: retrospective multifactorial analysis. Urol Int. 2020;104(5–6):452–458. doi: 10.1159/000504989. [DOI] [PubMed] [Google Scholar]
- 15.Karim SS, Hanna L, Geraghty R, Somani BK. Role of pelvicalyceal anatomy in the outcomes of retrograde intrarenal surgery (RIRS) for lower pole stones: outcomes with a systematic review of literature. Urolithiasis. 2020;48(3):263–270. doi: 10.1007/s00240-019-01150-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Dindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg. 2004;240:205–213. doi: 10.1097/01.sla.0000133083.54934.ae. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Bone RC, Balk RA, Cerra FB, et al. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. The ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/Society of Critical Care Medicine. Chest. 1992;101(6):1644–1655. doi: 10.1378/chest.101.6.1644. [DOI] [PubMed] [Google Scholar]
- 18.Wright A, Williams K, Somani B, Rukin N. Intrarenal pres- sure and irrigation flow with commonly used ureteric access sheaths and instruments. Cent European J Urol. 2015;68:434–438. doi: 10.5173/ceju.2015.604. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Zhong W, Zeng G, Wu K, et al. Does a smaller tract in percutaneous nephrolithotomy contribute to high renal pelvic pressure and postoperative fever? J Endourol. 2008;22:2147–2151. doi: 10.1089/end.2008.0001. [DOI] [PubMed] [Google Scholar]
- 20.Reicherz A, Maas V, Reike M et al. Striking a balance: outcomes of short-term Mono-J placement following ureterorenoscopy. Urolithiasis. 2021; Epub ahead of print [DOI] [PMC free article] [PubMed]
- 21.Kourambas J, Byrne RR, Preminger GM. Does a ureteral access sheath facilitate ureteroscopy? J Urol. 2001;165(3):789–793. doi: 10.1016/S0022-5347(05)66527-5. [DOI] [PubMed] [Google Scholar]
- 22.Al-Qahtani SM, Letendre J, Thomas A, et al. Which ureteral access sheath is compatible with your flexible ureteroscope? J Endourol. 2014;28(3):286–290. doi: 10.1089/end.2013.0375. [DOI] [PubMed] [Google Scholar]
- 23.Kaler KS, Lama DJ, Safiullah S, et al. Ureteral access sheath deployment: how much force is too much? Initial studies with a novel ureteral access sheath force sensor in the porcine ureter. J Endourol. 2019;33(9):712–718. doi: 10.1089/end.2019.0211. [DOI] [PubMed] [Google Scholar]
- 24.Pedro RN, Weiland D, Reardon S, Monga M. Ureteral access sheath insertion forces: implications for design and training. Urol Res. 2007;35(2):107–109. doi: 10.1007/s00240-007-0086-4. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.