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The Difficult Ureter: Clinical and Radiographic Characteristics Associated With Upper Urinary Tract Access at the Time of Ureteroscopic Stone Treatment
Endourology and Stones The Difficult Ureter: Clinical and Radiographic Characteristics Associated With Upper Urinary Tract Access at the Time of Ureteroscopic Stone Treatment Boyd R. Viers, Lyndsay D. Viers, Nathan C. Hull, Theodore J. Hanson, Ramila A. Mehta, Eric J. Bergstralh, Terri J. Vrtiska, and Amy E. Krambeck OBJECTIVE
MATERIALS AND METHODS
RESULTS
CONCLUSION
To evaluate the association between clinicoradiographic features and need for prestenting (PS) because of inability of the ureter to accommodate the ureteroscope, or ureteral access sheath, at the time of stone treatment. From 2009 to 2013, 120 consecutive nonstented patients underwent ureteroscopic stone treatment with preoperative computerized tomography urogram. Acute stone events with obstruction or infection were excluded. Preoperative radiographic imaging underwent radiologist review. Clinicoradiographic features were characterized, and multivariable logistic regression models were used to identify covariates independently associated with need for PS. Of the 154 renal units treated, 25 (16%) required PS for failed primary access. PS ureters were less likely to have a history of prior ipsilateral ureteral stent (4% vs 31%) or surgery (8% vs 36%; P <.05). Radiographically, PS ureters had a narrower ureteropelvic junction (4 mm vs 5 mm) and were more likely to have <50% ureteral opacification on computerized tomography urogram (32% vs 9%; P <.05). On multivariable analysis, prior ipsilateral ureteral stent (odds ratio [OR] ¼ 0.11) and stone surgery (OR ¼ 0.15) reduced the need for PS; meanwhile, <50% ureteral opacification (OR ¼ 4.41) was independently associated with an increased risk of access failure. We report a 16% incidence of access failure requiring PS at time of ureteroscopy. Clinically, there was an 89% and 85% risk reduction in the need for PS with prior history of ipsilateral ureteral stent or surgery. Radiographically, there was a 4.4-fold increased risk of PS with <50% ureteral opacification. Accordingly, our findings may assist in counseling and operative management of the difficult ureter. UROLOGY 86: 878e884, 2015. 2015 Elsevier Inc.
W
ith advancements in endoscopic technology including enhanced fiber optics, improved flexibility, tapered design, and increased utilization of ureteral access sheaths (UASs), retrograde ureteroscopy has emerged as a first-line treatment for renal and ureteral calculi <2 cm.1-4 Despite improvements in stone retrieval technique, upper tract access in the difficult ureter remains a challenge. Specifically, a 14Fr UAS is on average 4-8Fr larger than the unstented adult ureter.5,6 As such, attempting to place an oversized sheath may increase the risk for ureteral shear injury and subsequent stricture formation.6,7
Financial Disclosure: The authors declare that they have no relevant financial interests. From the Department of Urology, Mayo Clinic, Rochester, MN; the Department of Radiology, Mayo Clinic, Rochester, MN; and the Division of Health Science Research, Mayo Clinic, Rochester, MN Address correspondence to: Amy E. Krambeck, M.D., Department of Urology, Mayo Clinic, 200 1st SW, Rochester, MN 55905. E-mail: [email protected] Submitted: May 12, 2015, accepted (with revisions): August 10, 2015
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ª 2015 Elsevier Inc. All Rights Reserved
Reported rates of prestenting (PS) at the time of retrograde ureteroscopy are as high as 8%-15%.8-11 Ureteral PS allows for passive ureteral dilation12 and has proven to be highly efficacious in facilitating upper tract access13-16 for stone treatment.11,17,18 Nevertheless, PS is not without morbidity19-22 and may be associated with complications requiring emergency department (ED) evaluation in up to 20%.23 There remains a paucity of data regarding the predictors of failed upper tract retrograde access. As such, given the relatively high incidence of PS, reported benefits, need for secondary intervention, and potential for stent-related complications, we sought to identify the clinical and preoperative radiographic risk factors, complications, and outcomes associated with PS.
MATERIALS AND METHODS After institutional review board approval, we retrospectively reviewed all consecutive retrograde ureteroscopic stone http://dx.doi.org/10.1016/j.urology.2015.08.007 0090-4295/15
Table 1. Patient characteristics Patient Characteristics Age (y), median (IQR) Female gender, number (%) BMI, median (IQR) Diabetes, number (%) Inflammatory bowel disease, number (%) Benign prostatic hyperplasia, number (%) Prostate volume, cc (median; IQR) Recurrent UTI CTU to surgery, months (median; IQR) Laterality of surgery, number (%) R. URS L. URS B. URS Symptomatic, number (%) Pain Gross hematuria Infection Prior stone passage, number (%) Prior stone surgery, number (%) Prior stone surgeries, number (%) No prior surgery 1 prior surgery 2 prior surgeries >2 prior surgeries Mean (SD) Prior stent, number (%) Prior abdominal or pelvic surgery, number (%) Prior abdominal or pelvic radiation, number (%) Prior pyelonephritis, number (%) Postoperative imaging, number (%) Complication with prestenting, number (%) Pain, ED Bleeding, ED UTI Complication at URS, number (%) Ureteral injury Complication after stone treatment, number (%) Urosepsis Ureteral obstruction UTI SIRS Pain, ED Bleeding, ED Retained stent Urinary retention Yeast vaginitis
No Prestent (N ¼ 100) Prestented (N ¼ 20) Total (N ¼ 120) P Value 57.7 47 28.5 17 7 20 39.3 20 0.7
(49.5-67.0) (47) (24.4-32.6) (17) (7) (38) (33.2-50.0) (20) (0.3-2.0)
59.2 7 28.7 2 0 5 29.0 2 1.5
(43.3-68.4) (35) (26.9-30.4) (10) (0) (38) (23.5-48.6) (10) (0.8-4.8)
58.2 54 28.5 19 7 25 39.0 22 0.8
32 42 26 76 59 40 20 50 44
(32) (42) (26) (76) (59) (40) (20) (50) (44)
2 10 8 13 11 7 4 10 2
(10) (50) (40) (65) (55) (35) (20) (50) (10)
34 52 34 89 70 47 24 60 46
55 18 12 15 1.4 38 52 3 11 83
(55) (18) (12) (15) (2.8) (38) (52) (3) (11) (83) —
(4) (3) (18) (0) (2) (4) (1) (7) (1) (1) (1) (1)
(90) (10) (0) (0) (0.3) (5) (35) (0) (5) (75) (15) (5) (5) (5) (5) (5)z (30) (5) (0) (5) (10) (5) (0) (0) (5) (0)
73 20 12 15 1.2 39 59 3 12 98
4 3 18 0 2 4 1 7 1 1 1 1
18 2 0 0 0.1 1 7 0 1 15 3 1 1 1 1 1 6 1 0 1 2 1 0 0 1 0
5 4 24 1 2 5 3 8 1 1 2 1
(46.8-67.0) .89* (45) .32y (24.9-32.3) .55* (16) .42y (6) .22y (38) 1.00y (28.9-48.5) .41* (18) .29y (0.4-2.1) .02* .12y (28) (43) (28) (74) .30y (58) .74y (39) .68y (20) 1.00y (50) 1.00y (38) .004y .02y (61) (17) (10) (13) (2.6) .003* (33) .005y (49) .17y (3) .43y (10) .41y (82) .33y — —
(4) (3) (20) (0.8) (2) (4) (3) (7) (0.8) (0.8) (2) (0.8)
.87y .14y
BMI, body mass index; CTU, computerized tomography urogram; ED, emergency department; IQR, interquartile range; SD, standard deviation; SIRS, systemic inflammatory response syndrome; URS, ureteroscopy; UTI, urinary tract infection. * Kruskal Wallis. y Chi square. z Shear injury a time of primary attempted ureteral access sheath insertion.
procedures performed by a single surgeon (A.E.K.) between July 2009 and June 2013. We hypothesized that clinicoradiographic characteristics including a lack of prior ureteral instrumentation and stone passage, as well as upper urinary tract imaging suggesting intrinsic luminal narrowing on computerized tomography (CT) urogram would be associated with the need for ureteral PS. Those patients (N ¼ 120) with a pretreatment CT urogram within 6 months of ureteroscopic stone treatment formed the basis of this analysis. A CT urogram was indicated among patients presenting with hematuria or a history of urothelial cancer. Patients presenting
UROLOGY 86 (5), 2015
with an acute stone event and ureteral obstruction, or evidence of infection requiring stent decompression, were excluded from analysis. Pretreatment CT urogram studies underwent re-review by a genitourinary radiologist (T.J.V.) to quantify urinary stone characteristics, ureteral anatomy, and ureteral opacification on excretory imaging. Ureteral opacification was visually quantified and defined as <50% if less than one-half of the proximal ureter opacified at any point during the excretory phase in the absence of an obstructing ureteral stone. The radiologist was blinded to patient characteristics, upper tract access outcomes, complications, and stone-free rates (SFRs).
879
Table 2. Renal unit characteristics Renal Unit Characteristics
No Prestent (N ¼ 129)
Prestented (N ¼ 25)
60 (46) 69 (54)
7 (28) 18 (72)
Laterality of surgery, number (%) Right Left Type of URS, number (%) Rigid Flexible Both Ureteral access sheath, number (%) Ureteral balloon dilation, number (%) Ureteral coaxial serial dilation, number (%) Number of procedures to treat stone, mean (SD) Preoperative tamsulosin, number (%) Prior ipsilateral stone passage, number (%) Prior ipsilateral ureteral stent, number (%) Prior ipsilateral stone surgery, number (%) Stone free, number (%)
P Value .09* .64*
13 94 22 110 4 28 1.1 49 56 40 47 74
(10) (73) (17) (85) (3) (22) (0.3) (38) (43) (31) (36) (69)
1 20 4 25 3 15 2.0 5 9 1 2 17
(4) (80) (16) (100) (12) (60) (0.0) (20) (36) (4) (8) (90)
.04* .05* .0001* <.0001y .08* .38* .008* .004* .07*
Abbreviations as in Table 1. * Chi square. y Kruskal Wallis.
Clinical characteristics for each patient, complications, and treatment outcomes were recorded. Among patients who underwent bilateral retrograde ureteroscopy, each renal unit was analyzed separately. Ureteral injury was defined as a full thickness injury noted at the time of ureteroscopy, UAS removal, or contrast extravasation within the ureteral segment during retrograde pyeloureterogram after instrumentation. At the time of attempted flexible ureteroscopy, a 12/14Fr UAS (Cook Medical) was used in cases requiring flexible ureteroscopy. If the UAS was unable to be safely advanced, the 12Fr obturator was used to dilate the ureter. If unsuccessful, an 11/13Fr UAS placement was attempted. If there was failure to place the UAS, then serial coaxial dilation (6Fr-16Fr Boston Scientific) or balloon dilation (5Fr sheath, 4-cm balloon, 40 psi; Cook Medical) of the distal ureter was performed. If the ureter was still resistant to placement of the UAS, then advancement of the ureteroscope (7.5 Fr Flex-X2 Storz) over a wire was attempted in cases with small volume ureteral stones (5 mm). If the ureter continued to be nonaccommodating, a 7Fr double-J ureteral stent was placed. Patients that required PS underwent repeat retrograde ureteroscopy at a minimum of 7 days after the primary procedure. Follow-up included repeat imaging in the form of abdominal X-ray and ultrasound or CT for radiopaque stones and metabolic evaluation at 6-12 weeks after stone treatment. Stone-free status was defined as a residual stone burden <2 mm. Comparisons of clinicoradiographic features and the need for PS were performed using the 2 sample students t and chi-square tests, as appropriate. Univariable and stepwise forward selection multivariable Cox proportional logistic regression models were used to identify covariates independently associated with the need for PS. All reported P values were 2 sided, with P <.05 considered statistically significant. Statistical analyses were performed using the SAS software version 9.3 and version 9 JMP (SAS Institute, Cary, NC; www.sas.com).
RESULTS Among patients who underwent retrograde ureteroscopic stone treatment from 2009 to 2013, 120 had a CT urogram within 6 months of surgery (median ¼ 0.8 months; 880
interquartile range ¼ 0.4-2.1). In total, 116 (97%) patients were Caucasian. PS was performed in 20 (17%) patients, including 25 of 154 (16%) renal units. Patients were PS for a median 17 days (interquartile range ¼ 12-24) before secondary ureteroscopic intervention. Type of stone treatment included rigid ureteroscopy in 14 (9%), flexible ureteroscopy in 114 (74%), and a combination of both modalities in 26 (17%). A low-grade PS related complication occurred in 3 (15%) patients including 1 (5%) pain and 1 (5%) hematuria requiring ED evaluation and 1 (5%) urinary tract infection. During attempted primary UAS sheath insertion, 1 (5%) patient experienced ureteral shear injury requiring PS; however, after PS, no patient experienced subsequent intraoperative complication at the time of definitive stone treatment, and no patient was noted to have stone impaction secondary to PS. Those who were PS (N ¼ 20) less often had a history of prior stone surgery (10% vs 44%; P ¼ .004) or ureteral stent (5% vs 38%; P ¼ .005) and underwent fewer previous stone procedures (mean, 0.1 vs 1.4; P ¼ .003), compared with non-PS patients (N ¼ 100). Postoperative complications after ureteroscopy were noted (6 [30%] PS and 18 [18%] non-PS; P ¼ .14) with the most common events including pain requiring ED evaluation (8 [7%]), urinary tract infection (5 [4%]), and systemic inflammatory response syndrome (3 [3%]). There was no significant difference in other clinical characteristics including age, gender, body mass index, diabetes, prior stone passage, or abdominal surgery and radiation (Table 1). Clinical characteristics of each renal unit are presented in Table 2. There was no difference in previous ipsilateral stone passage (36% PS vs 43% non-PS; P ¼ .38); however, renal units requiring PS less often had prior ipsilateral stone surgery (8% vs 36%; P ¼ .004) or ureteral stent (4% vs 31%; P ¼ .008). At the time of stone treatment, PS renal units required a greater number stone procedures (mean, 2.0 vs 1.1; P <.0001) and were more likely to undergo ureteral balloon dilation (12% vs 3%; UROLOGY 86 (5), 2015
Table 3. Radiographic characteristics on CT urogram per renal unit Radiographic Characteristics Largest stone, AP diameter (mm); median (IQR) Volume largest stone (mm3); median (IQR) Number of stones to be treated, median (IQR) Stone density (HU), median (IQR) Location symptomatic stone to be treated, no. (%) Intrarenal UPJ Upper ureter Mid ureter Lower ureter UVJ Ureteral diameter (mm); median (IQR) UPJ 3 cm below UPJ Above stone Below stone At iliac vessels At pelvic inlet Ureteral wall thickness at iliac vessels (mm); median (IQR) Ureteral intraluminal-to-wall thickness ratio median (IQR) Opacification of ureter (10-min delay), number (%) Complete opacification >50% opacification <50% opacification Obstructed Periureteral fibrosis, number (%) Hydronephrosis, number (%) None Mild Moderate Severe Ureteral tortuosity, number (%) None Mild Moderate Width of subcutaneous fat (cm); median (IQR)
No Prestenting (N ¼ 129) 5.0 5.0 2 802
(3.0-6.0) (3.0-8.0) (1-2) (529-1053)
Prestenting (N ¼ 25) 4.0 5.0 2 800
(3.0-5.0) (4.0-7.0) (1-3) (560-953)
80 15 6 4 12 9
(62) (12) (5) (3) (9) (7)
18 1 2 1 3 0
(72) (4) (8) (4) (12) (0)
5.0 4.0 5.0 3.0 3.0 3.0 1.0 3.0
(3.0-6.0) (3.0-5.0) (3.0-7.0) (2.0-4.0) (2.0-4.0) (2.0-5.0) (1.0-1.0) (2.0-4.0)
4.0 3.0 3.0 1.0 3.0 3.0 1.0 3.0
(3.0-5.0) (3.0-4.0) (2.0-6.0) (1.0-2.0) (2.0-4.0) (2.0-4.0) (1.0-1.0) (1.0-4.0)
58 53 12 6 1
(45) (41) (9) (5) (0.8)
9 6 8 2 0
(36) (24) (32) (8) (0)
108 15 5 1
(84) (12) (4) (0.8)
21 2 2 0
(84) (8) (8) (0)
72 49 8 2.5
(56) (38) (6) (1.8-3.2)
16 6 3 3.1
(64) (24) (12) (1.8-3.5)
P Value .60* .95* .46* .58* .61y
.05* .12* .21* .09* .25* .53* .54* .26* .01y
.66y .75y
.30y
.43*
AP, anterior-posterior; HU, Hounsfield units; UPJ, ureteropelvic junction; UVJ, ureterovesical junction; other abbreviations as in Table 1. * Kruskal Wallis. y Chi square.
P ¼ .05) or coaxial serial dilation (60% vs 22%; P ¼ .0001) with the first procedure. However, PS patients were more likely to have successful UAS placement at the time of definitive stone management relative to unstented ureters (100% vs 85%; P ¼ .04). Differences in SFR (90% PS vs 69% non-PS) and utilization of preoperative Tamsulosin (20% PS vs 38% non-PS) approached statistical significance. Radiographic features on preoperative CT urogram are presented in Table 3. There was no significant difference in urinary stone volume, number, density, or location between cohorts. PS renal units had a significantly narrower ureteropelvic junction (4.0 vs 5.0 mm; P ¼ .05) and were more likely to have <50% ipsilateral ureteral opacification (32% vs 9%; P ¼ .01), whereas non-PS patients more often had >50% ureteral opacification (24% vs 41%). There was no significant difference in periureteral fibrosis, hydronephrosis, or ureteral tortuosity. On multivariable analysis (Table 4), controlling for significant predictors of PS on univariate analysis, a UROLOGY 86 (5), 2015
history of prior ipsilateral ureteral stent (odds ratio [OR] ¼ 0.11; 95% confidence interval [CI] ¼ 0.01-0.83; P ¼ .03) and prior ipsilateral surgery (OR ¼ 0.15; 95% CI ¼ 0.03-0.69; P ¼ .02) remained protective against the risk for PS, whereas <50% ipsilateral ureteral opacification on excretory phase CT urogram was independently associated with an increased risk of PS (OR ¼ 4.41; 95% CI ¼ 1.32-14.67; P ¼ .02).
COMMENT In a select cohort of patients undergoing retrograde ureteroscopy for the treatment of upper tract stone disease, we report a 17% incidence of PS per patient; of which, 15% of patients experienced low-grade PS related complications. Importantly, PS was associated with greater utilization of a UAS without an increase in perioperative complications at the time of definitive stone treatment. On multivariable analysis, a history of ipsilateral stone surgery and ureteral stent were protective, whereas <50% ureteral opacification on CT urogram was independently 881
Table 4. Risk of prestenting at time of stone treatment Unadjusted Risk Factor Age at surgery Gender (ref. female) Prior ipsilateral stent Prior ipsilateral surgery Prior ipsilateral stone passage CTU <50% ureteral opacification Preoperative tamsulosin UPJ diameter (mm)
Adjusted
OR
95% CI
P Value
Or
95% CI
P Value
1.00 1.85 0.09 0.15 0.73 4.30 0.41 0.88
0.97-1.02 0.75-4.59 0.01-0.72 0.03-0.66 0.30-1.78 1.38-13.40 0.14-1.16 0.72-1.08
.71 .19 .02 .01 .49 .02 .09 .22
— — 0.11 0.15 — 4.41 — —
— — 0.01-0.83 0.03-0.69 — 1.32-14.67 — —
— — .03* .02* — .02y — —
CI, confidence interval; OR, odds ratio; other abbreviations as in Tables 1 and 3. * Modeling for ureteral opacification. y Modeling for prior ipsilateral surgery and stent.
associated with an increased risk of PS at the time of retrograde ureteroscopic stone treatment. Significant advances in retrograde endoscopic technology have translated into a high-level of efficacy1-3 and subsequent increasing utilization24; resulting in retrograde ureteroscopy rapidly becoming the primary treatment of choice for upper tract stones <2 cm.4 Implementation of the UAS has positively impacted outcomes; in fact, many urologists have incorporated the use of a standard 14Fr UAS which has demonstrated a decrease in intrarenal pressures,25 augmented drainage and improved visibility,26 allowed for multiple reentries with decreased operative times,27 and enhanced SFR.28 Nevertheless, ureteroscopy, and the utilization of a UAS, is highly dependent on ureteral compliance. As such, even with the advent of small caliber ureteroscopes, primary ureteral access and stone treatment may not always be safe or feasible. As noted in a study of prospectively classified ureteral injuries at the time of UAS placement, Traxer and Thomas6 reported an overall incidence of 46.5% and found that only PS reliably reduced the risk of severe injury by up to 7-fold.6 Similarly, after PS, we observed no ureteral injuries with UAS insertion. Accordingly, the forceful manipulation of an intrinsically narrow ureter may significantly increase the risk of ureteral shear injury and should be taken into consideration at the time of primary stone treatment. Limited data exist defining the incidence and associated risk factors for failed upper tract access requiring PS. Previous analyses have reported an incidence of primary ureteroscopic access failure in 8%-15%.8-11 However, these studies are limited in their evaluation of associated features necessitating PS. More recently, in a prospective study evaluating successful 14Fr UAS insertion, Mogilevkin et al16 reported a primary failure rate of 22% in spite of sequential ureteral dilation. They found that older age (OR ¼ 1.5), previous ipsilateral ureteral instrumentation (OR 9.7), and PS (OR 22) before stone treatment were independently associated with successful UAS insertion.16 Similarly, our 16% incidence of primary upper tract access failure per ureter is congruent with these analyses despite 60% of PS patients undergoing sequential ureteral dilation. 882
Outcomes associated with PS have been investigated and are promising. Ambani et al13 reported successful ureteroscopic access in 71% of patients after PS for an average of 10 days with a 4.8-6Fr stent. Our results differed significantly as 100% of PS patients underwent successful UAS insertion and stone treatment at the time of definitive ureteroscopy. Discrepancies may be secondary to our use of a larger PS (7Fr) for a greater period (median ¼ 17 days) and their frequent utilization of only a flexible ureteroscope, which is more likely to buckle with axial force relative to a rigid UAS. Second, PS has been found to reduce the need for balloon dilation (2% vs 37%)15 and the subsequent 5% associated risk of ureteral perforation.29 Although balloon dilation was used in 12% of renal units before PS, subsequent balloon dilation after PS was not required, thus confirming the results of Bin et al.15 Importantly, PS has demonstrated superior SFR after definitive treatment.11,18 Rubenstein et al11 reported an SFR (<2 mm) of 78% vs 54% among PS patients. Similarly, in a match-paired analysis, Netsch et al18 evaluated 286 patients; of which, 143 were PS and noted a significantly improved overall SFR of 95% vs 87%. Our results mirror these findings as 90% of PS renal units were stone-free relative to 69% of unstented ureters; however, this finding did not reach statistical significance (P <.07) likely secondary to a lack of statistical power. Notably, our rate of UAS insertion was significantly greater among PS renal units (100% vs 85%) further suggesting a mechanism for improved stone-free outcomes. Our analysis expands on these studies by quantifying both clinical and radiographic characteristics associated with an increased risk of PS. Indeed, similar to Mogilevkin et al,30 we found that prior ipsilateral ureteral procedures where independently associated with an 85% risk reduction in need for PS. We also found that a history of prior ipsilateral ureteral stent was likewise associated with an 89% risk reduction in the need for PS. Importantly, our study is the first to evaluate the association between failed upper tract access and preoperative radiographic characteristics. Herein, we found that a lack of ureteral opacification, specifically <50%, on excretory UROLOGY 86 (5), 2015
phase imaging was independently associated with a 4.4fold increased risk of access failure. We hypothesize that this finding represents the intrinsic ureteral luminal narrowing encountered clinically with difficult passage of the ureteroscope or UAS. Although we did not identify any predictive characteristics on noncontrast phase imaging, we believe that our findings greatly assist the treating urologist in preoperative counseling and surgical planning. One must take into consideration complications associated with ureteral stenting.22 Importantly, we noted no difference in intra- or postoperative complications between cohorts. After PS, however, 15% of patients experienced a significant complication requiring ED evaluation; including a 5% incidence each of pain, bleeding, and infection. Although stenting will gradually dilate the ureter overtime, it is initially associated with ureteral hyperperistalsis and bladder wall irritability.12 Indeed, Joshi et al19 assessed stent-related quality of life and found that up to 80% of patients experienced bothersome symptoms. Furthermore, ureteral stents carry a risk of infectious complications including bacteriuria, colonization, and the development of resistant organisms.20 In an effort to reduce stent-related morbidity, it has been our practice to treat ureteral spasms with tamsulosin and anti-inflammatory agents, bladder irritability with anticholinergics, and place patients on antibiotic prophylaxis periprocedurally to avoid secondary infection. We recognize that our study is limited by its retrospective, nonrandomized nature. In an effort to control for this limitation, we evaluated only patients treated consecutively by a single surgeon using a standardized ureteroscopic protocol with available preoperative CT urogram. Second, although we did not achieve the statistical power to demonstrate significant differences in SFR, complications, or the potential benefits of preoperative tamsulosin, we were able to identify meaningful trends and independent predictors for access failure. Likewise, owing to the tertiary referral nature of our practice, we were unable to accurately define the number, and size, of prior stones passed which may account for the inability of stone passage to predict PS. Furthermore, our population was predominantly Caucasian and thus may not reflect findings among differing racial demographics. Finally, our findings highlight the need for additional prospective investigations to further define to risks and benefits of PS.
CONCLUSION In a select cohort of patients with preoperative CT urogram, we observed a 17% incidence per patient of primary upper tract access failure necessitating PS and a 15% incidence of PS-related complications. Among the clinicoradiographic characteristics investigated, prior ipsilateral ureteral surgery and stenting were protective, whereas <50% ureteral opacification was associated with UROLOGY 86 (5), 2015
an increased risk of access failure. Importantly, subsequent UAS placement was successful in all PS ureters. Accordingly, these findings should be taken into consideration during preoperative counseling and perioperative surgical planning. References 1. Breda A, Ogunyemi O, Leppert JT, Schulam PG. Flexible ureteroscopy and laser lithotripsy for multiple unilateral intrarenal stones. Eur Urol. 2009;55:1190-1196. 2. Hyams ES, Monga M, Pearle MS, et al. A prospective, multiinstitutional study of flexible ureteroscopy for proximal ureteral stones smaller than 2 cm. J Urol. 2015;193:165-169. 3. Perez Castro E, Osther PJ, Jinga V, et al. Differences in ureteroscopic stone treatment and outcomes for distal, mid-, proximal, or multiple ureteral locations: the Clinical Research Office of the Endourological Society ureteroscopy global study. Eur Urol. 2014;66: 102-109. 4. Preminger GM, Tiselius HG, Assimos DG, et al. 2007 guideline for the management of ureteral calculi. J Urol. 2007;178:2418-2434. 5. Zelenko N, Coll D, Rosenfeld AT, Smith RC. Normal ureter size on unenhanced helical CT. AJR Am J Roentgenol. 2004;182:1039-1041. 6. Traxer O, Thomas A. Prospective evaluation and classification of ureteral wall injuries resulting from insertion of a ureteral access sheath during retrograde intrarenal surgery. J Urol. 2013;189: 580-584. 7. Delvecchio FC, Auge BK, Brizuela RM, et al. Assessment of stricture formation with the ureteral access sheath. Urology. 2003;61: 518-522; discussion: 522. 8. Cetti RJ, Biers S, Keoghane SR. The difficult ureter: what is the incidence of pre-stenting? Ann R Coll Surgeons Engl. 2011;93:31-33. 9. Ji C, Gan W, Guo H, et al. A prospective trial on ureteral stenting combined with secondary ureteroscopy after an initial failed procedure. Urol Res. 2012;40:593-598. 10. Shields JM, Bird VG, Graves R, Gomez-Marin O. Impact of preoperative ureteral stenting on outcome of ureteroscopic treatment for urinary lithiasis. J Urol. 2009;182:2768-2774. 11. Rubenstein RA, Zhao LC, Loeb S, et al. Prestenting improves ureteroscopic stone-free rates. J Endourol. 2007;21:1277-1280. 12. Venkatesh R, Landman J, Minor SD, et al. Impact of a doublepigtail stent on ureteral peristalsis in the porcine model: initial studies using a novel implantable magnetic sensor. J Endourol. 2005; 19:170-176. 13. Ambani SN, Faerber GJ, Roberts WW, et al. Ureteral stents for impassable ureteroscopy. J Endourol. 2013;27:549-553. 14. Chu L, Farris CA, Corcoran AT, Averch TD. Preoperative stent placement decreases cost of ureteroscopy. Urology. 2011;78: 309-313. 15. Bin X, Friedlander JI, Chuang KW, et al. Predictive factors for intraoperative balloon dilation in semirigid ureteroscopic lithotripsy. J Endourol. 2012;26:988-991. 16. Mogilevkin Y, Sofer M, Margel D, et al. Predicting a successful ureteral access sheath insertion: a bi-center prospective study. J Endourol. 2014;28:1414-1417. 17. Chu L, Sternberg KM, Averch TD. Preoperative stenting decreases operative time and reoperative rates of ureteroscopy. J Endourol. 2011;25:751-754. 18. Netsch C, Knipper S, Bach T, et al. Impact of preoperative ureteral stenting on stone-free rates of ureteroscopy for nephroureterolithiasis: a matched-paired analysis of 286 patients. Urology. 2012; 80:1214-1219. 19. Joshi HB, Stainthorpe A, MacDonagh RP, et al. Indwelling ureteral stents: evaluation of symptoms, quality of life and utility. J Urol. 2003;169:1065-1069; discussion: 1069. 20. Kehinde EO, Rotimi VO, Al-Hunayan A, et al. Bacteriology of urinary tract infection associated with indwelling J ureteral stents. J Endourol. 2004;18:891-896.
883
21. Nabi G, Cook J, N’Dow J, McClinton S. Outcomes of stenting after uncomplicated ureteroscopy: systematic review and meta-analysis. BMJ. 2007;334:572. 22. Tang L, Gao X, Xu B, et al. Placement of ureteral stent after uncomplicated ureteroscopy: do we really need it? Urology. 2011;78:1248-1256. 23. Rapoport D, Perks AE, Teichman JM. Ureteral access sheath use and stenting in ureteroscopy: effect on unplanned emergency room visits and cost. J Endourol. 2007;21:993-997. 24. Oberlin DT, Flum AS, Bachrach L, et al. Contemporary surgical trends in the management of upper tract calculi. J Urol. 2015;193:880-884. 25. Auge BK, Pietrow PK, Lallas CD, et al. Ureteral access sheath provides protection against elevated renal pressures during routine flexible ureteroscopic stone manipulation. J Endourol. 2004;18:33-36.
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26. Stern JM, Yiee J, Park S. Safety and efficacy of ureteral access sheaths. J Endourol. 2007;21:119-123. 27. Kourambas J, Byrne RR, Preminger GM. Does a ureteral access sheath facilitate ureteroscopy? J Urol. 2001;165:789-793. 28. 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. 29. Kuntz NJ, Neisius A, Tsivian M, et al. Balloon dilation of the ureter: a contemporary review of outcomes and complications. J Urol. 2015;194:413-417. 30. Mogilevkin Y, Sofer M, Margel D, et al. Predicting an effective ureteral access sheath insertion: a bicenter prospective study. J Endourol. 2014;28:1414-1417.
UROLOGY 86 (5), 2015
MATERIALS AND METHODS
RESULTS
CONCLUSION
To evaluate the association between clinicoradiographic features and need for prestenting (PS) because of inability of the ureter to accommodate the ureteroscope, or ureteral access sheath, at the time of stone treatment. From 2009 to 2013, 120 consecutive nonstented patients underwent ureteroscopic stone treatment with preoperative computerized tomography urogram. Acute stone events with obstruction or infection were excluded. Preoperative radiographic imaging underwent radiologist review. Clinicoradiographic features were characterized, and multivariable logistic regression models were used to identify covariates independently associated with need for PS. Of the 154 renal units treated, 25 (16%) required PS for failed primary access. PS ureters were less likely to have a history of prior ipsilateral ureteral stent (4% vs 31%) or surgery (8% vs 36%; P <.05). Radiographically, PS ureters had a narrower ureteropelvic junction (4 mm vs 5 mm) and were more likely to have <50% ureteral opacification on computerized tomography urogram (32% vs 9%; P <.05). On multivariable analysis, prior ipsilateral ureteral stent (odds ratio [OR] ¼ 0.11) and stone surgery (OR ¼ 0.15) reduced the need for PS; meanwhile, <50% ureteral opacification (OR ¼ 4.41) was independently associated with an increased risk of access failure. We report a 16% incidence of access failure requiring PS at time of ureteroscopy. Clinically, there was an 89% and 85% risk reduction in the need for PS with prior history of ipsilateral ureteral stent or surgery. Radiographically, there was a 4.4-fold increased risk of PS with <50% ureteral opacification. Accordingly, our findings may assist in counseling and operative management of the difficult ureter. UROLOGY 86: 878e884, 2015. 2015 Elsevier Inc.
W
ith advancements in endoscopic technology including enhanced fiber optics, improved flexibility, tapered design, and increased utilization of ureteral access sheaths (UASs), retrograde ureteroscopy has emerged as a first-line treatment for renal and ureteral calculi <2 cm.1-4 Despite improvements in stone retrieval technique, upper tract access in the difficult ureter remains a challenge. Specifically, a 14Fr UAS is on average 4-8Fr larger than the unstented adult ureter.5,6 As such, attempting to place an oversized sheath may increase the risk for ureteral shear injury and subsequent stricture formation.6,7
Financial Disclosure: The authors declare that they have no relevant financial interests. From the Department of Urology, Mayo Clinic, Rochester, MN; the Department of Radiology, Mayo Clinic, Rochester, MN; and the Division of Health Science Research, Mayo Clinic, Rochester, MN Address correspondence to: Amy E. Krambeck, M.D., Department of Urology, Mayo Clinic, 200 1st SW, Rochester, MN 55905. E-mail: [email protected] Submitted: May 12, 2015, accepted (with revisions): August 10, 2015
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ª 2015 Elsevier Inc. All Rights Reserved
Reported rates of prestenting (PS) at the time of retrograde ureteroscopy are as high as 8%-15%.8-11 Ureteral PS allows for passive ureteral dilation12 and has proven to be highly efficacious in facilitating upper tract access13-16 for stone treatment.11,17,18 Nevertheless, PS is not without morbidity19-22 and may be associated with complications requiring emergency department (ED) evaluation in up to 20%.23 There remains a paucity of data regarding the predictors of failed upper tract retrograde access. As such, given the relatively high incidence of PS, reported benefits, need for secondary intervention, and potential for stent-related complications, we sought to identify the clinical and preoperative radiographic risk factors, complications, and outcomes associated with PS.
MATERIALS AND METHODS After institutional review board approval, we retrospectively reviewed all consecutive retrograde ureteroscopic stone http://dx.doi.org/10.1016/j.urology.2015.08.007 0090-4295/15
Table 1. Patient characteristics Patient Characteristics Age (y), median (IQR) Female gender, number (%) BMI, median (IQR) Diabetes, number (%) Inflammatory bowel disease, number (%) Benign prostatic hyperplasia, number (%) Prostate volume, cc (median; IQR) Recurrent UTI CTU to surgery, months (median; IQR) Laterality of surgery, number (%) R. URS L. URS B. URS Symptomatic, number (%) Pain Gross hematuria Infection Prior stone passage, number (%) Prior stone surgery, number (%) Prior stone surgeries, number (%) No prior surgery 1 prior surgery 2 prior surgeries >2 prior surgeries Mean (SD) Prior stent, number (%) Prior abdominal or pelvic surgery, number (%) Prior abdominal or pelvic radiation, number (%) Prior pyelonephritis, number (%) Postoperative imaging, number (%) Complication with prestenting, number (%) Pain, ED Bleeding, ED UTI Complication at URS, number (%) Ureteral injury Complication after stone treatment, number (%) Urosepsis Ureteral obstruction UTI SIRS Pain, ED Bleeding, ED Retained stent Urinary retention Yeast vaginitis
No Prestent (N ¼ 100) Prestented (N ¼ 20) Total (N ¼ 120) P Value 57.7 47 28.5 17 7 20 39.3 20 0.7
(49.5-67.0) (47) (24.4-32.6) (17) (7) (38) (33.2-50.0) (20) (0.3-2.0)
59.2 7 28.7 2 0 5 29.0 2 1.5
(43.3-68.4) (35) (26.9-30.4) (10) (0) (38) (23.5-48.6) (10) (0.8-4.8)
58.2 54 28.5 19 7 25 39.0 22 0.8
32 42 26 76 59 40 20 50 44
(32) (42) (26) (76) (59) (40) (20) (50) (44)
2 10 8 13 11 7 4 10 2
(10) (50) (40) (65) (55) (35) (20) (50) (10)
34 52 34 89 70 47 24 60 46
55 18 12 15 1.4 38 52 3 11 83
(55) (18) (12) (15) (2.8) (38) (52) (3) (11) (83) —
(4) (3) (18) (0) (2) (4) (1) (7) (1) (1) (1) (1)
(90) (10) (0) (0) (0.3) (5) (35) (0) (5) (75) (15) (5) (5) (5) (5) (5)z (30) (5) (0) (5) (10) (5) (0) (0) (5) (0)
73 20 12 15 1.2 39 59 3 12 98
4 3 18 0 2 4 1 7 1 1 1 1
18 2 0 0 0.1 1 7 0 1 15 3 1 1 1 1 1 6 1 0 1 2 1 0 0 1 0
5 4 24 1 2 5 3 8 1 1 2 1
(46.8-67.0) .89* (45) .32y (24.9-32.3) .55* (16) .42y (6) .22y (38) 1.00y (28.9-48.5) .41* (18) .29y (0.4-2.1) .02* .12y (28) (43) (28) (74) .30y (58) .74y (39) .68y (20) 1.00y (50) 1.00y (38) .004y .02y (61) (17) (10) (13) (2.6) .003* (33) .005y (49) .17y (3) .43y (10) .41y (82) .33y — —
(4) (3) (20) (0.8) (2) (4) (3) (7) (0.8) (0.8) (2) (0.8)
.87y .14y
BMI, body mass index; CTU, computerized tomography urogram; ED, emergency department; IQR, interquartile range; SD, standard deviation; SIRS, systemic inflammatory response syndrome; URS, ureteroscopy; UTI, urinary tract infection. * Kruskal Wallis. y Chi square. z Shear injury a time of primary attempted ureteral access sheath insertion.
procedures performed by a single surgeon (A.E.K.) between July 2009 and June 2013. We hypothesized that clinicoradiographic characteristics including a lack of prior ureteral instrumentation and stone passage, as well as upper urinary tract imaging suggesting intrinsic luminal narrowing on computerized tomography (CT) urogram would be associated with the need for ureteral PS. Those patients (N ¼ 120) with a pretreatment CT urogram within 6 months of ureteroscopic stone treatment formed the basis of this analysis. A CT urogram was indicated among patients presenting with hematuria or a history of urothelial cancer. Patients presenting
UROLOGY 86 (5), 2015
with an acute stone event and ureteral obstruction, or evidence of infection requiring stent decompression, were excluded from analysis. Pretreatment CT urogram studies underwent re-review by a genitourinary radiologist (T.J.V.) to quantify urinary stone characteristics, ureteral anatomy, and ureteral opacification on excretory imaging. Ureteral opacification was visually quantified and defined as <50% if less than one-half of the proximal ureter opacified at any point during the excretory phase in the absence of an obstructing ureteral stone. The radiologist was blinded to patient characteristics, upper tract access outcomes, complications, and stone-free rates (SFRs).
879
Table 2. Renal unit characteristics Renal Unit Characteristics
No Prestent (N ¼ 129)
Prestented (N ¼ 25)
60 (46) 69 (54)
7 (28) 18 (72)
Laterality of surgery, number (%) Right Left Type of URS, number (%) Rigid Flexible Both Ureteral access sheath, number (%) Ureteral balloon dilation, number (%) Ureteral coaxial serial dilation, number (%) Number of procedures to treat stone, mean (SD) Preoperative tamsulosin, number (%) Prior ipsilateral stone passage, number (%) Prior ipsilateral ureteral stent, number (%) Prior ipsilateral stone surgery, number (%) Stone free, number (%)
P Value .09* .64*
13 94 22 110 4 28 1.1 49 56 40 47 74
(10) (73) (17) (85) (3) (22) (0.3) (38) (43) (31) (36) (69)
1 20 4 25 3 15 2.0 5 9 1 2 17
(4) (80) (16) (100) (12) (60) (0.0) (20) (36) (4) (8) (90)
.04* .05* .0001* <.0001y .08* .38* .008* .004* .07*
Abbreviations as in Table 1. * Chi square. y Kruskal Wallis.
Clinical characteristics for each patient, complications, and treatment outcomes were recorded. Among patients who underwent bilateral retrograde ureteroscopy, each renal unit was analyzed separately. Ureteral injury was defined as a full thickness injury noted at the time of ureteroscopy, UAS removal, or contrast extravasation within the ureteral segment during retrograde pyeloureterogram after instrumentation. At the time of attempted flexible ureteroscopy, a 12/14Fr UAS (Cook Medical) was used in cases requiring flexible ureteroscopy. If the UAS was unable to be safely advanced, the 12Fr obturator was used to dilate the ureter. If unsuccessful, an 11/13Fr UAS placement was attempted. If there was failure to place the UAS, then serial coaxial dilation (6Fr-16Fr Boston Scientific) or balloon dilation (5Fr sheath, 4-cm balloon, 40 psi; Cook Medical) of the distal ureter was performed. If the ureter was still resistant to placement of the UAS, then advancement of the ureteroscope (7.5 Fr Flex-X2 Storz) over a wire was attempted in cases with small volume ureteral stones (5 mm). If the ureter continued to be nonaccommodating, a 7Fr double-J ureteral stent was placed. Patients that required PS underwent repeat retrograde ureteroscopy at a minimum of 7 days after the primary procedure. Follow-up included repeat imaging in the form of abdominal X-ray and ultrasound or CT for radiopaque stones and metabolic evaluation at 6-12 weeks after stone treatment. Stone-free status was defined as a residual stone burden <2 mm. Comparisons of clinicoradiographic features and the need for PS were performed using the 2 sample students t and chi-square tests, as appropriate. Univariable and stepwise forward selection multivariable Cox proportional logistic regression models were used to identify covariates independently associated with the need for PS. All reported P values were 2 sided, with P <.05 considered statistically significant. Statistical analyses were performed using the SAS software version 9.3 and version 9 JMP (SAS Institute, Cary, NC; www.sas.com).
RESULTS Among patients who underwent retrograde ureteroscopic stone treatment from 2009 to 2013, 120 had a CT urogram within 6 months of surgery (median ¼ 0.8 months; 880
interquartile range ¼ 0.4-2.1). In total, 116 (97%) patients were Caucasian. PS was performed in 20 (17%) patients, including 25 of 154 (16%) renal units. Patients were PS for a median 17 days (interquartile range ¼ 12-24) before secondary ureteroscopic intervention. Type of stone treatment included rigid ureteroscopy in 14 (9%), flexible ureteroscopy in 114 (74%), and a combination of both modalities in 26 (17%). A low-grade PS related complication occurred in 3 (15%) patients including 1 (5%) pain and 1 (5%) hematuria requiring ED evaluation and 1 (5%) urinary tract infection. During attempted primary UAS sheath insertion, 1 (5%) patient experienced ureteral shear injury requiring PS; however, after PS, no patient experienced subsequent intraoperative complication at the time of definitive stone treatment, and no patient was noted to have stone impaction secondary to PS. Those who were PS (N ¼ 20) less often had a history of prior stone surgery (10% vs 44%; P ¼ .004) or ureteral stent (5% vs 38%; P ¼ .005) and underwent fewer previous stone procedures (mean, 0.1 vs 1.4; P ¼ .003), compared with non-PS patients (N ¼ 100). Postoperative complications after ureteroscopy were noted (6 [30%] PS and 18 [18%] non-PS; P ¼ .14) with the most common events including pain requiring ED evaluation (8 [7%]), urinary tract infection (5 [4%]), and systemic inflammatory response syndrome (3 [3%]). There was no significant difference in other clinical characteristics including age, gender, body mass index, diabetes, prior stone passage, or abdominal surgery and radiation (Table 1). Clinical characteristics of each renal unit are presented in Table 2. There was no difference in previous ipsilateral stone passage (36% PS vs 43% non-PS; P ¼ .38); however, renal units requiring PS less often had prior ipsilateral stone surgery (8% vs 36%; P ¼ .004) or ureteral stent (4% vs 31%; P ¼ .008). At the time of stone treatment, PS renal units required a greater number stone procedures (mean, 2.0 vs 1.1; P <.0001) and were more likely to undergo ureteral balloon dilation (12% vs 3%; UROLOGY 86 (5), 2015
Table 3. Radiographic characteristics on CT urogram per renal unit Radiographic Characteristics Largest stone, AP diameter (mm); median (IQR) Volume largest stone (mm3); median (IQR) Number of stones to be treated, median (IQR) Stone density (HU), median (IQR) Location symptomatic stone to be treated, no. (%) Intrarenal UPJ Upper ureter Mid ureter Lower ureter UVJ Ureteral diameter (mm); median (IQR) UPJ 3 cm below UPJ Above stone Below stone At iliac vessels At pelvic inlet Ureteral wall thickness at iliac vessels (mm); median (IQR) Ureteral intraluminal-to-wall thickness ratio median (IQR) Opacification of ureter (10-min delay), number (%) Complete opacification >50% opacification <50% opacification Obstructed Periureteral fibrosis, number (%) Hydronephrosis, number (%) None Mild Moderate Severe Ureteral tortuosity, number (%) None Mild Moderate Width of subcutaneous fat (cm); median (IQR)
No Prestenting (N ¼ 129) 5.0 5.0 2 802
(3.0-6.0) (3.0-8.0) (1-2) (529-1053)
Prestenting (N ¼ 25) 4.0 5.0 2 800
(3.0-5.0) (4.0-7.0) (1-3) (560-953)
80 15 6 4 12 9
(62) (12) (5) (3) (9) (7)
18 1 2 1 3 0
(72) (4) (8) (4) (12) (0)
5.0 4.0 5.0 3.0 3.0 3.0 1.0 3.0
(3.0-6.0) (3.0-5.0) (3.0-7.0) (2.0-4.0) (2.0-4.0) (2.0-5.0) (1.0-1.0) (2.0-4.0)
4.0 3.0 3.0 1.0 3.0 3.0 1.0 3.0
(3.0-5.0) (3.0-4.0) (2.0-6.0) (1.0-2.0) (2.0-4.0) (2.0-4.0) (1.0-1.0) (1.0-4.0)
58 53 12 6 1
(45) (41) (9) (5) (0.8)
9 6 8 2 0
(36) (24) (32) (8) (0)
108 15 5 1
(84) (12) (4) (0.8)
21 2 2 0
(84) (8) (8) (0)
72 49 8 2.5
(56) (38) (6) (1.8-3.2)
16 6 3 3.1
(64) (24) (12) (1.8-3.5)
P Value .60* .95* .46* .58* .61y
.05* .12* .21* .09* .25* .53* .54* .26* .01y
.66y .75y
.30y
.43*
AP, anterior-posterior; HU, Hounsfield units; UPJ, ureteropelvic junction; UVJ, ureterovesical junction; other abbreviations as in Table 1. * Kruskal Wallis. y Chi square.
P ¼ .05) or coaxial serial dilation (60% vs 22%; P ¼ .0001) with the first procedure. However, PS patients were more likely to have successful UAS placement at the time of definitive stone management relative to unstented ureters (100% vs 85%; P ¼ .04). Differences in SFR (90% PS vs 69% non-PS) and utilization of preoperative Tamsulosin (20% PS vs 38% non-PS) approached statistical significance. Radiographic features on preoperative CT urogram are presented in Table 3. There was no significant difference in urinary stone volume, number, density, or location between cohorts. PS renal units had a significantly narrower ureteropelvic junction (4.0 vs 5.0 mm; P ¼ .05) and were more likely to have <50% ipsilateral ureteral opacification (32% vs 9%; P ¼ .01), whereas non-PS patients more often had >50% ureteral opacification (24% vs 41%). There was no significant difference in periureteral fibrosis, hydronephrosis, or ureteral tortuosity. On multivariable analysis (Table 4), controlling for significant predictors of PS on univariate analysis, a UROLOGY 86 (5), 2015
history of prior ipsilateral ureteral stent (odds ratio [OR] ¼ 0.11; 95% confidence interval [CI] ¼ 0.01-0.83; P ¼ .03) and prior ipsilateral surgery (OR ¼ 0.15; 95% CI ¼ 0.03-0.69; P ¼ .02) remained protective against the risk for PS, whereas <50% ipsilateral ureteral opacification on excretory phase CT urogram was independently associated with an increased risk of PS (OR ¼ 4.41; 95% CI ¼ 1.32-14.67; P ¼ .02).
COMMENT In a select cohort of patients undergoing retrograde ureteroscopy for the treatment of upper tract stone disease, we report a 17% incidence of PS per patient; of which, 15% of patients experienced low-grade PS related complications. Importantly, PS was associated with greater utilization of a UAS without an increase in perioperative complications at the time of definitive stone treatment. On multivariable analysis, a history of ipsilateral stone surgery and ureteral stent were protective, whereas <50% ureteral opacification on CT urogram was independently 881
Table 4. Risk of prestenting at time of stone treatment Unadjusted Risk Factor Age at surgery Gender (ref. female) Prior ipsilateral stent Prior ipsilateral surgery Prior ipsilateral stone passage CTU <50% ureteral opacification Preoperative tamsulosin UPJ diameter (mm)
Adjusted
OR
95% CI
P Value
Or
95% CI
P Value
1.00 1.85 0.09 0.15 0.73 4.30 0.41 0.88
0.97-1.02 0.75-4.59 0.01-0.72 0.03-0.66 0.30-1.78 1.38-13.40 0.14-1.16 0.72-1.08
.71 .19 .02 .01 .49 .02 .09 .22
— — 0.11 0.15 — 4.41 — —
— — 0.01-0.83 0.03-0.69 — 1.32-14.67 — —
— — .03* .02* — .02y — —
CI, confidence interval; OR, odds ratio; other abbreviations as in Tables 1 and 3. * Modeling for ureteral opacification. y Modeling for prior ipsilateral surgery and stent.
associated with an increased risk of PS at the time of retrograde ureteroscopic stone treatment. Significant advances in retrograde endoscopic technology have translated into a high-level of efficacy1-3 and subsequent increasing utilization24; resulting in retrograde ureteroscopy rapidly becoming the primary treatment of choice for upper tract stones <2 cm.4 Implementation of the UAS has positively impacted outcomes; in fact, many urologists have incorporated the use of a standard 14Fr UAS which has demonstrated a decrease in intrarenal pressures,25 augmented drainage and improved visibility,26 allowed for multiple reentries with decreased operative times,27 and enhanced SFR.28 Nevertheless, ureteroscopy, and the utilization of a UAS, is highly dependent on ureteral compliance. As such, even with the advent of small caliber ureteroscopes, primary ureteral access and stone treatment may not always be safe or feasible. As noted in a study of prospectively classified ureteral injuries at the time of UAS placement, Traxer and Thomas6 reported an overall incidence of 46.5% and found that only PS reliably reduced the risk of severe injury by up to 7-fold.6 Similarly, after PS, we observed no ureteral injuries with UAS insertion. Accordingly, the forceful manipulation of an intrinsically narrow ureter may significantly increase the risk of ureteral shear injury and should be taken into consideration at the time of primary stone treatment. Limited data exist defining the incidence and associated risk factors for failed upper tract access requiring PS. Previous analyses have reported an incidence of primary ureteroscopic access failure in 8%-15%.8-11 However, these studies are limited in their evaluation of associated features necessitating PS. More recently, in a prospective study evaluating successful 14Fr UAS insertion, Mogilevkin et al16 reported a primary failure rate of 22% in spite of sequential ureteral dilation. They found that older age (OR ¼ 1.5), previous ipsilateral ureteral instrumentation (OR 9.7), and PS (OR 22) before stone treatment were independently associated with successful UAS insertion.16 Similarly, our 16% incidence of primary upper tract access failure per ureter is congruent with these analyses despite 60% of PS patients undergoing sequential ureteral dilation. 882
Outcomes associated with PS have been investigated and are promising. Ambani et al13 reported successful ureteroscopic access in 71% of patients after PS for an average of 10 days with a 4.8-6Fr stent. Our results differed significantly as 100% of PS patients underwent successful UAS insertion and stone treatment at the time of definitive ureteroscopy. Discrepancies may be secondary to our use of a larger PS (7Fr) for a greater period (median ¼ 17 days) and their frequent utilization of only a flexible ureteroscope, which is more likely to buckle with axial force relative to a rigid UAS. Second, PS has been found to reduce the need for balloon dilation (2% vs 37%)15 and the subsequent 5% associated risk of ureteral perforation.29 Although balloon dilation was used in 12% of renal units before PS, subsequent balloon dilation after PS was not required, thus confirming the results of Bin et al.15 Importantly, PS has demonstrated superior SFR after definitive treatment.11,18 Rubenstein et al11 reported an SFR (<2 mm) of 78% vs 54% among PS patients. Similarly, in a match-paired analysis, Netsch et al18 evaluated 286 patients; of which, 143 were PS and noted a significantly improved overall SFR of 95% vs 87%. Our results mirror these findings as 90% of PS renal units were stone-free relative to 69% of unstented ureters; however, this finding did not reach statistical significance (P <.07) likely secondary to a lack of statistical power. Notably, our rate of UAS insertion was significantly greater among PS renal units (100% vs 85%) further suggesting a mechanism for improved stone-free outcomes. Our analysis expands on these studies by quantifying both clinical and radiographic characteristics associated with an increased risk of PS. Indeed, similar to Mogilevkin et al,30 we found that prior ipsilateral ureteral procedures where independently associated with an 85% risk reduction in need for PS. We also found that a history of prior ipsilateral ureteral stent was likewise associated with an 89% risk reduction in the need for PS. Importantly, our study is the first to evaluate the association between failed upper tract access and preoperative radiographic characteristics. Herein, we found that a lack of ureteral opacification, specifically <50%, on excretory UROLOGY 86 (5), 2015
phase imaging was independently associated with a 4.4fold increased risk of access failure. We hypothesize that this finding represents the intrinsic ureteral luminal narrowing encountered clinically with difficult passage of the ureteroscope or UAS. Although we did not identify any predictive characteristics on noncontrast phase imaging, we believe that our findings greatly assist the treating urologist in preoperative counseling and surgical planning. One must take into consideration complications associated with ureteral stenting.22 Importantly, we noted no difference in intra- or postoperative complications between cohorts. After PS, however, 15% of patients experienced a significant complication requiring ED evaluation; including a 5% incidence each of pain, bleeding, and infection. Although stenting will gradually dilate the ureter overtime, it is initially associated with ureteral hyperperistalsis and bladder wall irritability.12 Indeed, Joshi et al19 assessed stent-related quality of life and found that up to 80% of patients experienced bothersome symptoms. Furthermore, ureteral stents carry a risk of infectious complications including bacteriuria, colonization, and the development of resistant organisms.20 In an effort to reduce stent-related morbidity, it has been our practice to treat ureteral spasms with tamsulosin and anti-inflammatory agents, bladder irritability with anticholinergics, and place patients on antibiotic prophylaxis periprocedurally to avoid secondary infection. We recognize that our study is limited by its retrospective, nonrandomized nature. In an effort to control for this limitation, we evaluated only patients treated consecutively by a single surgeon using a standardized ureteroscopic protocol with available preoperative CT urogram. Second, although we did not achieve the statistical power to demonstrate significant differences in SFR, complications, or the potential benefits of preoperative tamsulosin, we were able to identify meaningful trends and independent predictors for access failure. Likewise, owing to the tertiary referral nature of our practice, we were unable to accurately define the number, and size, of prior stones passed which may account for the inability of stone passage to predict PS. Furthermore, our population was predominantly Caucasian and thus may not reflect findings among differing racial demographics. Finally, our findings highlight the need for additional prospective investigations to further define to risks and benefits of PS.
CONCLUSION In a select cohort of patients with preoperative CT urogram, we observed a 17% incidence per patient of primary upper tract access failure necessitating PS and a 15% incidence of PS-related complications. Among the clinicoradiographic characteristics investigated, prior ipsilateral ureteral surgery and stenting were protective, whereas <50% ureteral opacification was associated with UROLOGY 86 (5), 2015
an increased risk of access failure. Importantly, subsequent UAS placement was successful in all PS ureters. Accordingly, these findings should be taken into consideration during preoperative counseling and perioperative surgical planning. References 1. Breda A, Ogunyemi O, Leppert JT, Schulam PG. Flexible ureteroscopy and laser lithotripsy for multiple unilateral intrarenal stones. Eur Urol. 2009;55:1190-1196. 2. Hyams ES, Monga M, Pearle MS, et al. A prospective, multiinstitutional study of flexible ureteroscopy for proximal ureteral stones smaller than 2 cm. J Urol. 2015;193:165-169. 3. Perez Castro E, Osther PJ, Jinga V, et al. Differences in ureteroscopic stone treatment and outcomes for distal, mid-, proximal, or multiple ureteral locations: the Clinical Research Office of the Endourological Society ureteroscopy global study. Eur Urol. 2014;66: 102-109. 4. Preminger GM, Tiselius HG, Assimos DG, et al. 2007 guideline for the management of ureteral calculi. J Urol. 2007;178:2418-2434. 5. Zelenko N, Coll D, Rosenfeld AT, Smith RC. Normal ureter size on unenhanced helical CT. AJR Am J Roentgenol. 2004;182:1039-1041. 6. Traxer O, Thomas A. Prospective evaluation and classification of ureteral wall injuries resulting from insertion of a ureteral access sheath during retrograde intrarenal surgery. J Urol. 2013;189: 580-584. 7. Delvecchio FC, Auge BK, Brizuela RM, et al. Assessment of stricture formation with the ureteral access sheath. Urology. 2003;61: 518-522; discussion: 522. 8. Cetti RJ, Biers S, Keoghane SR. The difficult ureter: what is the incidence of pre-stenting? Ann R Coll Surgeons Engl. 2011;93:31-33. 9. Ji C, Gan W, Guo H, et al. A prospective trial on ureteral stenting combined with secondary ureteroscopy after an initial failed procedure. Urol Res. 2012;40:593-598. 10. Shields JM, Bird VG, Graves R, Gomez-Marin O. Impact of preoperative ureteral stenting on outcome of ureteroscopic treatment for urinary lithiasis. J Urol. 2009;182:2768-2774. 11. Rubenstein RA, Zhao LC, Loeb S, et al. Prestenting improves ureteroscopic stone-free rates. J Endourol. 2007;21:1277-1280. 12. Venkatesh R, Landman J, Minor SD, et al. Impact of a doublepigtail stent on ureteral peristalsis in the porcine model: initial studies using a novel implantable magnetic sensor. J Endourol. 2005; 19:170-176. 13. Ambani SN, Faerber GJ, Roberts WW, et al. Ureteral stents for impassable ureteroscopy. J Endourol. 2013;27:549-553. 14. Chu L, Farris CA, Corcoran AT, Averch TD. Preoperative stent placement decreases cost of ureteroscopy. Urology. 2011;78: 309-313. 15. Bin X, Friedlander JI, Chuang KW, et al. Predictive factors for intraoperative balloon dilation in semirigid ureteroscopic lithotripsy. J Endourol. 2012;26:988-991. 16. Mogilevkin Y, Sofer M, Margel D, et al. Predicting a successful ureteral access sheath insertion: a bi-center prospective study. J Endourol. 2014;28:1414-1417. 17. Chu L, Sternberg KM, Averch TD. Preoperative stenting decreases operative time and reoperative rates of ureteroscopy. J Endourol. 2011;25:751-754. 18. Netsch C, Knipper S, Bach T, et al. Impact of preoperative ureteral stenting on stone-free rates of ureteroscopy for nephroureterolithiasis: a matched-paired analysis of 286 patients. Urology. 2012; 80:1214-1219. 19. Joshi HB, Stainthorpe A, MacDonagh RP, et al. Indwelling ureteral stents: evaluation of symptoms, quality of life and utility. J Urol. 2003;169:1065-1069; discussion: 1069. 20. Kehinde EO, Rotimi VO, Al-Hunayan A, et al. Bacteriology of urinary tract infection associated with indwelling J ureteral stents. J Endourol. 2004;18:891-896.
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