Understanding failures in getting it up: The prevalence and predictors of failed ureteral access in ureteroscopy.

INTRODUCTION: Failed access ureteroscopy (FA) describes the inability to gain adequate access to a stone to allow for treatment. The purpose of this study was to identify the prevalence of, and factors predicting FA in patients presenting with renal and ureteral stones. METHODS: We conducted a retrospective review of all ureteroscopy (URS) procedures performed for renal and ureteral stones by three endourologists over a six-month period at our center. All patients who underwent URS for the purpose of stone treatment were included. Patients were excluded if they underwent URS for non-stone diagnosis or treatment. FA was investigated in relation to demographics, medical history, stone-specific characteristics, procedure-specific characteristics, etc. Statistical analysis consisted of descriptive statistics, as well as Chi-squared and t-test analysis using SPSS statistical software version 24.0. RESULTS: A total of 188 cases were reviewed, with 8% of patients experiencing FA. Patient age, gender, body mass index (BMI), American Society of Anesthesiologists (ASA) score, emergency cases, previous stone treatment, use of computed tomography (CT) imaging, presence of hydronephrosis, and surgeon did not differ significantly between FA and successful access (SA) groups. Stone size (9.88±5.8 vs. 8.76±4.3 mm; p=0.361) was also not significantly different. However, a significant difference was noted in time from first diagnosis to URS (128 vs. 65 days, p=0.044) between the FA and SA groups, respectively. Similarly, for ureteral stones, the FA group had a significantly greater proportion of stones located in the proximal ureter (62.5% vs. 22.0%, p=0.043). CONCLUSIONS: Proximal ureteric stones were more likely to result in FA URS, and FA procedures were more likely to be preceded by extended time from first diagnosis to URS. Further investigation is necessary, and all endourology centers should track their own personal outcome data to allow for more meaningful analysis to be performed to improve patient outcomes.

Patient Reported Outcomes Predicting Spontaneous Stone Passage May Not Have Acceptable Accuracy.

PURPOSE: We assessed the accuracy of patient reported outcomes for predicting spontaneous ureteral stone passage. MATERIALS AND METHODS: Patients with new unilateral ureteral calculi were prospectively assessed regarding current symptoms and whether they believed their stone had passed. The primary outcome was successful spontaneous stone passage as confirmed by ultrasound, and kidney, ureter and bladder x-ray. Spontaneous stone passage was compared to patient reported outcome responses to assess accuracy. RESULTS: Of the 212 patients 105 (49.5%) had successful spontaneous stone passage at a mean followup of 17.6 days. Compared to the unsuccessful spontaneous stone passage group, those with successful spontaneous stone passage had significantly smaller (mean 5.4 vs 7.6 mm), more distal (71.4% vs 34.6%) stones with slightly longer average time to followup at first visit (19.2 vs 16.0 days). Additionally, there was more patient reported cessation of pain (77.1% vs 44.9%) and perceived stone passage (55.2% vs 13.1%) in this group. Cessation of pain was 79.7% (95% CI 67.1-89.0) sensitive and 55.8% (95% CI 44.0-67.1) specific for successful spontaneous stone passage. Likewise, patient reported stone passage was 59.3% (95% CI 45.7-71.9) sensitive and 87.0% (95% CI 77.4-93.5%) specific. In the multivariable logistic regression analysis cessation of pain (OR 4.02, 95% CI 1.91-8.47, p <0.01) and reported stone passage (OR 3.79, 95% CI 1.73-8.28, p <0.01) were independent predictors of successful spontaneous stone passage. CONCLUSIONS: Cessation of pain and patient reported stone passage are independent predictors of successful spontaneous stone passage. However, both assessments may incorrectly gauge spontaneous stone passage, which raises concern for their validity as a sole clinical end point.

Quality and cost assessment of Canadian Urological Association microscopic hematuria guidelines in clinical practice: Turning urine into gold.

INTRODUCTION: Asymptomatic microscopic hematuria (AMH) is defined in the Canadian Urological Association (CUA) guideline as >2 red blood cells (RBCs) per high-powered field (HPF). Our objective was to evaluate guideline adherence for AMH at our center. Secondarily, we aimed to identify areas of the guideline that can be optimized. METHODS: We retrospectively reviewed 875 consecutive adults referred to two urologists for hematuria between June 2010 and June 2016. Patient characteristics, risk factors, and outcomes were added to an encrypted Research Electronic Data Capture (REDCap) database. Evaluation of microscopic hematuria reporting was performed by analyzing 681 urine samples reported as 1-5 RBC/HPF. Healthcare costs were obtained from Alberta Health Services (AHS), Data Integration and Management Repository (DIMR), and Alberta Society of Radiologists (ASR). RESULTS: Of the 875 patients referred with hematuria, 400 had AMH. Overall, 96.5% completed evaluation consistent with the CUA guideline. The incidence of pathology requiring surgical intervention was 21/400 (5%) with a 0.8% rate (3/400) of urothelial cell carcinoma (UCC) (non-invasive, low-grade). No malignancy was found in non-smokers with normal cytology, normal imaging and <50 RBC/HPF; 44% had AMH in the 1-5 RBCs/HPF range. Only 41% (279/681) of urine samples categorized as 1-5 RBCs/ HPF had guideline-defined microscopic hematuria. By changing local microscopic hematuria reporting to differentiate 1-2 and 3-5 RBCs/HPF, we estimate $745 000 in annual savings. CONCLUSIONS: At our center, CUA AMH guideline adherence is high. We did not find malignancy in non-smokers with normal cytology, imaging and <50 RBC/HPF. We identified and changed regional microscopic hematuria reporting to fit the CUA definition, eliminating unnecessary investigations and healthcare costs.

Complications in the 90-day postoperative period following kidney transplant and the relationship of the Charlson Comorbidity Index.

INTRODUCTION: Renal transplant experiences widespread success, but little is published regarding the postoperative complications. The Charlson Comorbidity Index (CCI) is a system of mortality risk assessment. Our purpose is to assess the 90-day postoperative complications after renal transplantation. The secondary objective is to clarify whether CCI predicts complications. We hypothesized increased CCI corresponds to worse complication on the Clavien scale. METHODS: This is a retrospective analysis of renal recipients at our institution (2011-2013) who were ≥18 years old and received complete follow up. CCI, age, gender, body mass index (BMI), and graft type were extracted from the electronic medical records. Complications were scored using the Clavien scale. Descriptive statistics and logistic regression were used to analyze 198 patients. RESULTS: The mean age was 53 (standard deviation [SD] 14), mean BMI 27.4 (SD 14), median CCI 1. Grade 2 or higher (significant) complications occurred in 60% of patients and Grade 3b or higher (severe) in 15% of patients in the 90-day postoperative period. Sixty-eight different complications were identified, the most common being blood transfusion (19%). Logistic regression suggests a predictive value of CCI (odds ratio [OR] 1.70; 95% confidence interval [CI] 1.3-2.3) for severe complications, with diabetes mellitus and peripheral vascular disease conferring increased risk. CONCLUSIONS: Renal transplant carries significant risk. This data can be used to improve patient counselling on the likely postoperative course. Study limitations include the retrospective design, predisposing to potential bias in data capture.

The "Acute" Stone Clinic Effect: Improving Healthcare Delivery by Reorganizing Clinical Resources.

OBJECTIVE: To determine the time to specialist urologic consultation and definitive management after establishing a subspecialist administered acute stone clinic (ASC) for adults with symptomatic upper tract stones in a publically funded universal healthcare system. MATERIALS AND METHODS: We retrospectively reviewed 337 adult referrals for stone management. Three distinct 9-week periods were assessed. Group 1 patients were seen/treated by their individual urologist before inception of a general urology emergency clinic (pre-EC). Group 2 patients were seen in a pooled EC and Group 3 patients were seen in the ASC. RESULTS: A total of 337 patients (75, pre-EC; 91, EC; 171, ASC) were reviewed. Mean time to consultation for pre-EC, EC, and ASC cohorts was 29, 7, and 7 days, respectively (p < 0.05), whereas loss to follow-up decreased from 13% to 5% (p < 0.05). On average, the number of patients seen per week increased from 9 to 20. Mean time to stone surgery from date of referral was 75 days pre-EC, 43 days EC, and 25 days ASC (p < 0.05). The percentage of patients undergoing surgery was between 59% and 63% per cohort; however, the number of patients increased from 5 to 11 per week. CONCLUSIONS: By reorganizing clinical resources, a dedicated ASC was able to increase patient capacity, reduce time to urologist consultation and reduce surgical wait times.

Are We Banging Our Heads Against the Wall? The Effect of Treatment Head Wear on the Outcomes of Extracorporeal Shockwave Lithotripsy.

INTRODUCTION AND OBJECTIVE: The manufacturer for the Storz Modulith SLX-F2 lithotripter recommends treatment head exchange after 1.65 million shocks. However, there is no documentation describing longevity of the treatment head with continued usage. The objective of this study is to determine whether there is a difference in stone fragmentation effectiveness with the treatment head at the beginning versus the end of its treatment life. METHODS: We conducted a retrospective chart review of 200 patients-50 consecutive patients treated immediately preceding, and following, two separate treatment head exchanges. Primary outcome measures were stone-free rate (no stone), total stone fragmentation (any decrease in size), and fragmentation rate ≤4 mm (decrease in size with largest residual fragment ≤4 mm), based on most recent follow-up imaging post shockwave. RESULTS: There were no baseline characteristic differences between the pre-exchange and postexchange groups with respect to first time lithotripsy for the stone (85% vs. 77%), stone location, preoperative stenting (3% vs. 4%), mean stone density (912 hounsfield units [HU] vs. 840 HU), mean stone size (9.0 mm vs. 8.1 mm), stone location, and mean number of shocks delivered (3105 vs. 3089). Mean time to follow-up was 2.7 weeks in both groups, with most follow-up imaging consisting of a kidney ureter bladder X-ray (87% pre-exchange vs. 85% postexchange). Stone free (34% vs. 27%), total stone fragmentation (76% vs. 76%), fragmentation ≤4 mm (48% vs. 42%), re-treatment rates (38% vs. 51%), and complication rates (6% vs. 7%), were not statistically different between the pre and postexchange groups, respectively. CONCLUSIONS: Exchanging the Storz Modulith F2 lithotripter head at the manufacturer recommended 1.65 million shocks does not affect the stone-free or fragmentation rate. If the manufacturer's recommendation for treatment head longevity is based on clinical outcomes, then there is likely room to extend this number without affecting treatment efficacy.

Preoperative skin antiseptics for preventing surgical site infections: what to do?

BACKGROUND: Safe and effective patient preoperative skin antisepsis is recommended to prevent surgical site infections (SSIs), reduce patient morbidity, and reduce systemic costs. However, there is lack of consensus among best practice recommendations regarding the optimal skin antiseptic solution and method of application. METHODS: In 2010 and 2011 the health technology appraisal committee of the Surgery Operational Clinical Network (SOCN), of Alberta Health Services (AHS), conducted an environmental scan to determine the current preoperative skin antisepsis in Alberta, reviewed key publications and existing guidelines, and requested a systematic review from the Canadian Agency for Drugs and Technologies in Health (CADTH). Using this information, and an established protocol for evidence-informed recommendations, the health technology appraisal committee made recommendations that were, in 2012, reviewed and endorsed by the SOCN executive and the AHS-Infection Prevention and Control (IPC) group. RESULTS: The environmental scan revealed practice variation in the types of antiseptic solutions and application methods being used in the 18 Alberta hospitals surveyed. The systematic review suggested that preoperative antiseptic showering reduces skin flora but the effect on SSI rates was inconclusive. While the review found no conclusive evidence to recommend an optimal antiseptic solution or application method, the results of two large randomized controlled trials suggest that chlorhexidine in 70% alcohol is more effective than povidone iodine in the prevention of SSIs. These results and the recommendations from Safer Healthcare Now!, a program of the Canadian Patient Safety Institute (CPSI), were used to inform the recommendations for AHS. These recommendations included abandoning preoperative showering with antiseptics except for special cases (high-risk surgeries such as sternotomies and implants as recommended by IPC) and standardizing skin antiseptic application methods and solution to chlorhexidine (CHG) in 70% alcohol. The exception would be procedures involving the ear, eye, mouth, mucous membranes, neural tissue, infants and emergent trauma cases where povidine iodine should be used. CONCLUSION: Using the best available evidence it was recommended that AHS standardize surgical skin antisepsis to 2% CHG in 70% alcohol as the preferred antiseptic and povidone iodine, as an alternative when CHG is contraindicated, to reduce SSIs, practice variation, and health care costs. Further research is required to determine the optimal skin antiseptic solution to reduce SSIs.

Stones lodge at three sites of anatomic narrowing in the ureter: clinical fact or fiction?

UNLABELLED: Abstract Background and Purpose: Throughout the literature, the ureter is described as having three anatomic sites of narrowing at which kidney stones typically become lodged: The ureteropelvic junction (UPJ), the ureteral crossing of the iliac vessels, and the ureterovesical junction (UVJ). There is little evidence to support this notion, however. The purpose of our study is to evaluate whether three peaks in stone distribution corresponding to these anatomic landmarks exist. METHODS: We retrospectively reviewed the kidneys-ureters-bladder (KUB) films of 622 patients with solitary ureteral calculi referred for shockwave lithotripsy (SWL). Pretreatment KUB films were used to categorize the location of their ureteral stone relative to 1 of 19 levels referenced to the axial skeleton. CT scans of 74 patients were used to determine the location of the UPJ, ureteral crossing of the iliac vessels, and UVJ relative to the 19 levels on KUB radiography. Histograms were then constructed to plot the distribution of stones within the ureter relative to these 19 levels. The effect of sex, stone size and side, and presence of a stent on stone distribution were analyzed. RESULTS: There are two peaks in the distribution of stones within the ureter in patients referred for SWL that correspond to the UPJ/proximal ureter and intramural ureter/UVJ. In patients with larger stones (≥100 mm(2)) or a ureteral stent in place, stones were distributed more proximally (P<0.0001). When comparing sexes, there was a difference in stone distribution that approached significance (P=0.0523), with a greater peak more distally in males compared with females. CONCLUSIONS: Our review demonstrates a peak in the distribution of stones corresponding to the UPJ/proximal ureter and the intramural ureter/UVJ. We failed to demonstrate a peak in stone distribution corresponding with the ureteral crossing of the iliac vessels.

Ureteral avulsion during contemporary ureteroscopic stone management: "the scabbard avulsion".

Ureteral avulsion during ureteroscopic stone management is extremely rare. To date, many publications reporting avulsion have been associated with "blind basket extraction" under fluoroscopy and the use of the Dormia stone basket. Fortunately, despite the significant rise in the numbers of ureteroscopic cases being performed, the rate of ureteral avulsion remains low. This is likely in part because of improvements in ureteroscope technology and stone manipulation devices. We present three recent cases of ureteral avulsion referred to our center for further management. To our knowledge, these cases represent the first published description of avulsion where the ureteroscope became wedged in the intramural ureter, resulting in full-length avulsion of the ureter. The avulsion occurs both proximally and distally with a resultant length of ureter left attached to the ureteroscope. We dub this mechanism the "scabbard" avulsion. We describe the most likely mechanism of this injury, with suggestions on how to prevent it and how to release the ureteroscope should it become wedged in the intramural ureter.

Predictors of health-related quality of life recovery following laparoscopic simple, radical and donor nephrectomy.

OBJECTIVES: To objectively quantify the recovery of health-related quality of life (HRQL) in patients undergoing laparoscopic nephrectomy. To determine which factors are predictive of a more expedited recovery. MATERIALS AND METHODS: Patient recovery was prospectively measured among patients undergoing laparoscopic simple (n= 12), radical (n= 42) and donor (n= 95) nephrectomy. All procedures were performed using a 3- or 4-trocar, transperitoneal fully-laparoscopic technique with intact specimen extraction using impermeable sacs for simple and radical nephrectomy, and hand extraction for donor nephrectomy. Postoperative recovery and quality of life were measured using the Postoperative Recovery Scale (PRS) administered preoperatively, immediately postoperatively and as an outpatient at 4, 8, 12, and 16 weeks postoperatively. ANOVA and Pearson's χ² tests were performed on demographic data. Multivariate logistic regression analysis was used to calculate odds ratios for factors predictive of recovery. RESULTS: Statistically significant differences were found at baseline for age (P = 0.02), gender (P < 0.01), body mass index (BMI; P = 0.03), surgical side (P < 0.01) and activity-based lifestyle (P = 0.04) across the three groups. Minimal adverse events were seen. Factors predictive of expedited recovery include age < 50 years (OR: 2.1, P < 0.01), body-mass index (BMI) < 30 kg/m² (OR: 1.7, P < 0.01), active lifestyles (OR: 1.3, P < 0.01) and those patients undergoing nephrectomy for benign or malignant indications rather than for organ donation (OR: 1.4, P < 0.01). There was a significant delay in the donor group vs the non-donor group with respect to the median number of days both groups took to recover 75% and 90% of their baseline PRS scores (11 days, P = 0.02; 20 days, P = 0.02, respectively). CONCLUSIONS: Predictive factors of recovery from laparoscopic nephrectomy include age, BMI, lifestyle and surgical indication. Differences between HRQL recovery following donor vs non-donor laparoscopic nephrectomy are significant, and suggest the possible interplay of underlying psychological factors.

Medical expulsive therapy as an adjunct to improve shockwave lithotripsy outcomes: a systematic review and meta-analysis.

BACKGROUND AND PURPOSE: Modern shockwave lithotripsy (SWL) is associated with inferior results compared with the original Dornier HM3. To enhance SWL outcomes, improved patient selection based on radiographic features and modulation of shockwave delivery rate have been used. A growing body of evidence demonstrates the positive effect of medical expulsive therapy (MET) to improve spontaneous passage of urinary calculi. The purpose of this review is to tabulate the current available data that examine the addition of MET to SWL to enhance outcomes. MATERIALS AND METHODS: MEDLINE was searched with a strategy developed in conjunction with a medical librarian. Trials were included if patients were randomized to receive either a medical expulsive agent or placebo or standard therapy after SWL. Study quality was assessed according to the Cochrane Renal Group criteria. The data were analyzed using RevMan meta-analysis software. Subgroup analysis was performed with respect to MET agent used, stone size, and duration of follow-up. RESULTS: Four randomized trials were identified. MET agents varied, with two trials using tamsulosin, one using nifedipine, and a single trial using Phyllanthus niruri extract. Two trials included patients with renal calculi, one had patients with ureteral calculi, and the fourth included patients with both ureteral and renal calculi. The pool results of the four trials included 212 patients who received MET and 206 who received placebo. The absolute risk difference of a successful outcome after SWL with the addition of MET was significantly superior to control at 17% (95% confidence interval [CI] 9%-24%); means six patients need to be treated with MET to prevent a single unsuccessful SWL of six (95% CI 4-11). The effect of MET post-SWL was even more pronounced for stones larger than 10 mm with an absolute risk difference of 26% (95% CI, 9%-43%). CONCLUSIONS: MET post-SWL results in a significant increase in successful treatment outcomes. Further powered, randomized studies are encouraged.

Impact of arterial and arteriovenous renal clamping with and without intrarenal cooling on renal oxygenation and temperature in a porcine model.

BACKGROUND: As laparoscopic partial nephrectomy increases in prominence, more needs to be understood about the combined effect of the pneumoperitoneum and renal ischemia during tumor resection. The purpose of this study is to investigate the effect of combined renal hilar clamping (arterial only versus arteriovenous) and retrograde intrarenal cooling on renal temperature and oxygenation in a porcine laparoscopic partial nephrectomy model. MATERIALS AND METHODS: Under general anesthesia, laparoscopic access with intra-abdominal pressure of 15 mm Hg to the left renal hilum was obtained. Licox tissue oxygenation and temperature probes were placed into the kidney transcutaneously; measurements were taken every 30 seconds. After establishing baseline readings, either the artery alone (n=18) or the artery and vein (n=18) were clamped for 30, 60 or 90 minutes (n=12 each). During vascular clamping, retrograde, intrarenal cooling was performed with ice cold saline infused via a percutaneously placed ureteric catheter in 18 pigs. Changes in renal pO2 and temperature were analyzed with repeated measures ANCOVA in SPSS 16. RESULTS: Retrograde cooling decreased renal parenchyma to 75.8% of baseline temperature (27.9 degrees C) within 15 minutes. There were no differences in cooling whether arterial or arteriovenous clamping was used (p=0.79). In uncooled animals, there was no significant difference in the decrease in renal pO2 during the clamp phase (p=0.18) or during the recovery phase (p=0.52). During the recovery phase, renal pO2 in uncooled animals was significantly higher than in those who received cooling (p=0.01). Animals who underwent hilar clamping for extended periods (60 and 90 min) had a slower recovery of renal pO2 to baseline than those with hilar clamping for 30 minutes (p=0.04) CONCLUSION: Retrograde intrarenal cooling can reliably cool the porcine kidney to 28 degrees C, regardless of whether arterial or arteriovenous clamping is used. Renal pO2 is not significantly different between animals that undergo artery only versus en bloc hilar clamping. Pigs that were provided with retrograde cooling had a slower return of pO2 to baseline following release of hilar clamps, possibly due to hypothermic vasospasm. Clamp durations greater than 60 minutes were also associated with slower return of renal oxygenation to baseline.

Stone attenuation and skin-to-stone distance on computed tomography predicts for stone fragmentation by shock wave lithotripsy.

OBJECTIVES: To determine whether stone attenuation and the skin-to-stone distance (SSD) can predict for stone fragmentation by SWL independently. Identifying the factors predictive of shock wave lithotripsy (SWL) outcome would help streamline the care of patients with stones. METHODS: A retrospective review was performed of 111 patients undergoing initial SWL for a solitary, 5-20 mm, renal calculus. Stone size, location, attenuation value, and SSD were determined on pretreatment noncontrast computed tomography. The outcome was categorized as stone free, complete fragmentation <5 mm, and incomplete fragmentation >or=5 mm or unchanged at 2 weeks on kidney/ureter/bladder radiography. RESULTS: After SWL, 44 (40%) were stone free, 27 (24%) had complete fragmentation, and 40 (36%) of 111 patients had incomplete fragmentation. The stone attenuation of the successfully treated patients (stone free and complete fragmentation groups) was 837 +/- 277 Hounsfield units (HU) vs 1092 +/- 254 HU for those with treatment failure (incomplete fragmentation; P < .01). The mean SSD also differed: 9.6 cm +/- 2.0 vs 11.1 cm +/- 2.5 for the successful treatment group vs the treatment failure group, respectively (P = .01). On multivariate analysis, the factors that independently predicted the outcome were stone attenuation, SSD, and stone composition. When patients were stratified into 4 risk groups (stone <900 HU and SSD <9.0 cm, stone <900 HU and SSD >or=9.0 cm, stone >or=900 HU and SSD <9.0 cm, and stone >or=900 HU and SSD >or=9.0 cm), the SWL success rate was 91%, 79%, 58%, and 41%, respectively (odds ratio 7.1, 95% confidence interval 1.6-32 for <900 HU and SSD <9.0 cm group vs other 3 risk groups; P = .01). CONCLUSIONS: The results of our study have shown that a stone attenuation of <900 HU, SSD of <9 cm, and stone composition predict for SWL success, independent of stone size, location, and body mass index. These factors will be considered important in the prospective design of a SWL treatment nomogram at our center.

Prospective determination of ureteral orifice location: a guide for fluoroscopic ureteral stent insertion.

PURPOSE: Ureteral stents are commonly inserted under fluoroscopic guidance. Our objective was to determine the intravesical landmarks for stent insertion by mapping the fluoroscopic location of the ureteral orifices (UOs) and bladder neck (BN) in relation to the pubic symphysis (PS). METHODS: In patients undergoing ureteroscopy, the UO to BN distance was measured during cystoscopy with a 5F ureteral catheter. Radiographic distance between the UO, BN, and superior border of the PS was determined by mapping their locations on digital fluoroscopic images. Measurements were performed with a full (to 50 cm H2O) and empty bladder. RESULTS: With an empty bladder, the mean cystoscopic BN to UO distance was 1.8 cm (+/- 0.4) for men (n = 10) and 2.0 cm (+/- 0.4) for women (n = 11). With a full bladder, it was 2.8 cm (+/- 0.5) for men and 2.9 cm (+/- 0.6) for women. Although the intravesical distance lengthened during cystoscopy (by 50%), there was no difference when viewed fluoroscopically; the BN to UO distance lengthened by only 15%. In men, the UOs were located superior to PS in the majority (83% and 95%, empty and full bladder, respectively). In women, however, the UOs resided behind the PS (73% and 50%, empty and full bladder, respectively). The BN in men was also cephalad to that in women (P = 0.01); superior to the PS in 50%; and behind the upper two thirds of the PS in 50%. In women, the BN was behind the lower two thirds of the PS in the majority (81%). CONCLUSIONS: During fluoroscopic ureteral stent insertion, the radiopaque marker of the stent positioner is situated at the superior border of the PS in men and behind the lower one third of the PS in women, permitting formation of an intravesical distal coil. One way to remember this is that men are on top and women are on the bottom of the PS.