Computerized Decision Support for Bladder Cancer Treatment Response Assessment in CT Urography: Effect on Diagnostic Accuracy in Multi-Institution Multi-Specialty Study.

This observer study investigates the effect of computerized artificial intelligence (AI)-based decision support system (CDSS-T) on physicians' diagnostic accuracy in assessing bladder cancer treatment response. The performance of 17 observers was evaluated when assessing bladder cancer treatment response without and with CDSS-T using pre- and post-chemotherapy CTU scans in 123 patients having 157 pre- and post-treatment cancer pairs. The impact of cancer case difficulty, observers' clinical experience, institution affiliation, specialty, and the assessment times on the observers' diagnostic performance with and without using CDSS-T were analyzed. It was found that the average performance of the 17 observers was significantly improved (p = 0.002) when aided by the CDSS-T. The cancer case difficulty, institution affiliation, specialty, and the assessment times influenced the observers' performance without CDSS-T. The AI-based decision support system has the potential to improve the diagnostic accuracy in assessing bladder cancer treatment response and result in more consistent performance among all physicians.

Intraobserver Variability in Bladder Cancer Treatment Response Assessment With and Without Computerized Decision Support.

We evaluated the intraobserver variability of physicians aided by a computerized decision-support system for treatment response assessment (CDSS-T) to identify patients who show complete response to neoadjuvant chemotherapy for bladder cancer, and the effects of the intraobserver variability on physicians' assessment accuracy. A CDSS-T tool was developed that uses a combination of deep learning neural network and radiomic features from computed tomography (CT) scans to detect bladder cancers that have fully responded to neoadjuvant treatment. Pre- and postchemotherapy CT scans of 157 bladder cancers from 123 patients were collected. In a multireader, multicase observer study, physician-observers estimated the likelihood of pathologic T0 disease by viewing paired pre/posttreatment CT scans placed side by side on an in-house-developed graphical user interface. Five abdominal radiologists, 4 diagnostic radiology residents, 2 oncologists, and 1 urologist participated as observers. They first provided an estimate without CDSS-T and then with CDSS-T. A subset of cases was evaluated twice to study the intraobserver variability and its effects on observer consistency. The mean areas under the curves for assessment of pathologic T0 disease were 0.85 for CDSS-T alone, 0.76 for physicians without CDSS-T and improved to 0.80 for physicians with CDSS-T (P = .001) in the original evaluation, and 0.78 for physicians without CDSS-T and improved to 0.81 for physicians with CDSS-T (P = .010) in the repeated evaluation. The intraobserver variability was significantly reduced with CDSS-T (P < .0001). The CDSS-T can significantly reduce physicians' variability and improve their accuracy for identifying complete response of muscle-invasive bladder cancer to neoadjuvant chemotherapy.

Deep Learning Approach for Assessment of Bladder Cancer Treatment Response.

We compared the performance of different Deep learning-convolutional neural network (DL-CNN) models for bladder cancer treatment response assessment based on transfer learning by freezing different DL-CNN layers and varying the DL-CNN structure. Pre- and posttreatment computed tomography scans of 123 patients (cancers, 129; pre- and posttreatment cancer pairs, 158) undergoing chemotherapy were collected. After chemotherapy 33% of patients had T0 stage cancer (complete response). Regions of interest in pre- and posttreatment scans were extracted from the segmented lesions and combined into hybrid pre -post image pairs (h-ROIs). Training (pairs, 94; h-ROIs, 6209), validation (10 pairs) and test sets (54 pairs) were obtained. The DL-CNN consisted of 2 convolution (C1-C2), 2 locally connected (L3-L4), and 1 fully connected layers. The DL-CNN was trained with h-ROIs to classify cancers as fully responding (stage T0) or not fully responding to chemotherapy. Two radiologists provided lesion likelihood of being stage T0 posttreatment. The test area under the ROC curve (AUC) was 0.73 for T0 prediction by the base DL-CNN structure with randomly initialized weights. The base DL-CNN structure with pretrained weights and transfer learning (no frozen layers) achieved test AUC of 0.79. The test AUCs for 3 modified DL-CNN structures (different C1-C2 max pooling filter sizes, strides, and padding, with transfer learning) were 0.72, 0.86, and 0.69. For the base DL-CNN with (C1) frozen, (C1-C2) frozen, and (C1-C2-L3) frozen, the test AUCs were 0.81, 0.78, and 0.71, respectively. The radiologists' AUCs were 0.76 and 0.77. DL-CNN performed better with pretrained than randomly initialized weights.

Real-World Impact of Minimally Invasive Versus Open Radical Cystectomy on Perioperative Outcomes and Spending.

OBJECTIVE: To evaluate the effect of the minimally invasive approach on spending and perioperative outcomes for patients undergoing radical cystectomy for bladder cancer. In a randomized control trial conducted at high-volume centers, robotic, and open cystectomy were shown to have similar outcomes. However, because the majority of cystectomies are performed in low-volume centers, it is unknown whether these findings are broadly generalizable. MATERIALS AND METHODS: We identified Medicare patients who underwent radical cystectomy for bladder cancer between 2008 and 2015. We examined the length of stay, readmission rate, and 90-day spending after minimally invasive or open cystectomy. We used multiple regressions to estimate the association between minimally invasive surgery and the outcomes, accounting for patient, hospital, and surgeon factors that may influence these outcomes. RESULTS: Of 4760 patients, 693 (14.6%) underwent minimally invasive cystectomy and 4067 (85.4%) had an open approach. Minimally invasive cystectomy was associated with shorter length of stay (10.1 days vs 11.9 days, P <.001), but no difference in readmission rate (27.4% vs 26.8%, P = .77). Minimally invasive cystectomy was associated with lower adjusted 90-day episode spending ($34,369 vs $38,071, P <.001). CONCLUSION: In patients across diverse institutions in the United States, minimally invasive cystectomy was associated with a shorter length of stay than open cystectomy and reduced 90-day episode spending, but with no significant difference in readmission rate.

Retroperitoneal versus transperitoneal robotic-assisted laparoscopic partial nephrectomy: a matched-pair, bicenter analysis with cost comparison using time-driven activity-based costing.

PURPOSE OF REVIEW: To perform a bicenter, retrospective study of perioperative outcomes of retroperitoneal versus transperitoneal robotic-assisted laparoscopic partial nephrectomy (RALPN) and assess costs using time-driven activity-based costing (TDABC). We identified 355 consecutive patients who underwent RALPN at University of California Los Angeles and the University of Michigan during 2009-2016. We matched according to RENAL nephrometry score, date, and institution for 78 retroperitoneal versus 78 transperitoneal RALPN. Unadjusted analyses were performed using McNemar's Chi-squared or paired t test, and adjusted analyses were performed using multivariable repeated measures regression analysis. From multivariable models, predicted probabilities were derived according to approach. Cost analysis was performed using TDABC. RECENT FINDINGS: Patients treated with retroperitoneal versus transperitoneal RALPN were similar in age (P = 0.490), sex (P = 0.715), BMI (P = 0.273), and comorbidity (P = 0.393). Most tumors were posterior or lateral in both the retroperitoneal (92.3%) and transperitoneal (85.9%) groups. Retroperitoneal RALPN was associated with shorter operative times (167.0 versus 191.1 min, P = 0.001) and length of stay (LOS) (1.8 versus 2.7 days, P < 0.001). There were no differences in renal function preservation or cancer control. In adjusted analyses, retroperitoneal RALPN was 17.6-min shorter (P < 0.001) and had a 76% lower probability of LOS at least 2 days (P < 0.001). Utilizing TDABC, transperitoneal RALPN added $2337 in cost when factoring in disposable equipment, operative time, LOS, and personnel. SUMMARY: In two high-volume, tertiary centers, retroperitoneal RALPN is associated with reduced operative times and shortened LOS in posterior and lateral tumors, whereas sharing similar clinicopathologic outcomes, which may translate into lower healthcare costs. Further investigation into anterior tumors is needed.

Bladder Cancer Treatment Response Assessment in CT using Radiomics with Deep-Learning.

Cross-sectional X-ray imaging has become the standard for staging most solid organ malignancies. However, for some malignancies such as urinary bladder cancer, the ability to accurately assess local extent of the disease and understand response to systemic chemotherapy is limited with current imaging approaches. In this study, we explored the feasibility that radiomics-based predictive models using pre- and post-treatment computed tomography (CT) images might be able to distinguish between bladder cancers with and without complete chemotherapy responses. We assessed three unique radiomics-based predictive models, each of which employed different fundamental design principles ranging from a pattern recognition method via deep-learning convolution neural network (DL-CNN), to a more deterministic radiomics feature-based approach and then a bridging method between the two, utilizing a system which extracts radiomics features from the image patterns. Our study indicates that the computerized assessment using radiomics information from the pre- and post-treatment CT of bladder cancer patients has the potential to assist in assessment of treatment response.

Bladder Cancer Segmentation in CT for Treatment Response Assessment: Application of Deep-Learning Convolution Neural Network-A Pilot Study.

Assessing the response of bladder cancer to neoadjuvant chemotherapy is crucial for reducing morbidity and increasing quality of life of patients. Changes in tumor volume during treatment is generally used to predict treatment outcome. We are developing a method for bladder cancer segmentation in CT using a pilot data set of 62 cases. 65 000 regions of interests were extracted from pre-treatment CT images to train a deep-learning convolution neural network (DL-CNN) for tumor boundary detection using leave-one-case-out cross-validation. The results were compared to our previous AI-CALS method. For all lesions in the data set, the longest diameter and its perpendicular were measured by two radiologists, and 3D manual segmentation was obtained from one radiologist. The World Health Organization (WHO) criteria and the Response Evaluation Criteria In Solid Tumors (RECIST) were calculated, and the prediction accuracy of complete response to chemotherapy was estimated by the area under the receiver operating characteristic curve (AUC). The AUCs were 0.73 ± 0.06, 0.70 ± 0.07, and 0.70 ± 0.06, respectively, for the volume change calculated using DL-CNN segmentation, the AI-CALS and the manual contours. The differences did not achieve statistical significance. The AUCs using the WHO criteria were 0.63 ± 0.07 and 0.61 ± 0.06, while the AUCs using RECIST were 0.65 ± 007 and 0.63 ± 0.06 for the two radiologists, respectively. Our results indicate that DL-CNN can produce accurate bladder cancer segmentation for calculation of tumor size change in response to treatment. The volume change performed better than the estimations from the WHO criteria and RECIST for the prediction of complete response.

Treatment Response Assessment for Bladder Cancer on CT Based on Computerized Volume Analysis, World Health Organization Criteria, and RECIST.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of our autoinitialized cascaded level set 3D segmentation system as compared with the World Health Organization (WHO) criteria and the Response Evaluation Criteria In Solid Tumors (RECIST) for estimation of treatment response of bladder cancer in CT urography. MATERIALS AND METHODS: CT urograms before and after neoadjuvant chemo-therapy treatment were collected from 18 patients with muscle-invasive localized or locally advanced bladder cancers. The disease stage as determined on pathologic samples at cystectomy after chemotherapy was considered as reference standard of treatment response. Two radiologists measured the longest diameter and its perpendicular on the pre- and posttreatment scans. Full 3D contours for all tumors were manually outlined by one radiologist. The autoinitialized cascaded level set method was used to automatically extract 3D tumor boundary. The prediction accuracy of pT0 disease (complete response) at cystectomy was estimated by the manual, autoinitialized cascaded level set, WHO, and RECIST methods on the basis of the AUC. RESULTS: The AUC for prediction of pT0 disease at cystectomy was 0.78 ± 0.11 for autoinitialized cascaded level set compared with 0.82 ± 0.10 for manual segmentation. The difference did not reach statistical significance (p = 0.67). The AUCs using RECIST criteria were 0.62 ± 0.16 and 0.71 ± 0.12 for the two radiologists, both lower than those of the two 3D methods. The AUCs using WHO criteria were 0.56 ± 0.15 and 0.60 ± 0.13 and thus were lower than all other methods. CONCLUSION: The pre- and posttreatment 3D volume change estimates obtained by the radiologist's manual outlines and the autoinitialized cascaded level set segmentation were more accurate for irregularly shaped tumors than were those based on RECIST and WHO criteria.

The impact of technology diffusion on treatment for prostate cancer.

BACKGROUND: The use of local therapy for prostate cancer may increase because of the perceived advantages of new technologies such as intensity-modulated radiotherapy (IMRT) and robotic prostatectomy. OBJECTIVE: To examine the association of market-level technological capacity with receipt of local therapy. DESIGN: Retrospective cohort. SUBJECTS: Patients with localized prostate cancer who were diagnosed between 2003 and 2007 (n=59,043) from the Surveillance Epidemiology and End Results-Medicare database. MEASURES: We measured the capacity for delivering treatment with new technology as the number of providers offering robotic prostatectomy or IMRT per population in a market (hospital referral region). The association of this measure with receipt of prostatectomy, radiotherapy, or observation was examined with multinomial logistic regression. RESULTS: For each 1000 patients diagnosed with prostate cancer, 174 underwent prostatectomy, 490 radiotherapy, and 336 were observed. Markets with high robotic prostatectomy capacity had higher use of prostatectomy (146 vs. 118 per 1000 men, P=0.008) but a trend toward decreased use of radiotherapy (574 vs. 601 per 1000 men, P=0.068), resulting in a stable rate of local therapy. High versus low IMRT capacity did not significantly impact the use of prostatectomy (129 vs. 129 per 1000 men, P=0.947) and radiotherapy (594 vs. 585 per 1000 men, P=0.579). CONCLUSIONS: Although there was a small shift from radiotherapy to prostatectomy in markets with high robotic prostatectomy capacity, increased capacity for both robotic prostatectomy and IMRT did not change the overall rate of local therapy. Our findings temper concerns that the new technology spurs additional therapy of prostate cancer.

Disparities in bladder cancer.

Among men, bladder cancer is the fourth most common malignancy and ninth leading cause of death from cancer in the United States. In contrast, it is the 11th most common malignancy and 12th leading cause of death from cancer among women. The successful management of bladder cancer largely depends on its timely diagnosis and treatment. Unfortunately, barriers disproportionately delay detection and treatment for individuals with social, economic, and community disadvantages. This imbalance creates health disparities (i.e., differences in health outcomes that are closely linked to these disadvantages), which negatively affect vulnerable populations, such as racial and ethnic minority groups, those from lower socioeconomic classes, and the uninsured. To obtain a better understanding of this issue, we review the current state of bladder cancer disparities research.

Use of restaging bladder tumor resection for bladder cancer among Medicare beneficiaries.

OBJECTIVE: To evaluate the use and effectiveness of restaging bladder tumor resection using population-based data. Restaging bladder tumor resection improves staging accuracy and the response to intravesical therapy. However, its use outside of a tertiary care setting, and its subsequent clinical implications, are unknown. METHODS: We identified 62 016 patients diagnosed with bladder cancer between 1992 and 2005 using SEER-Medicare data. Restaging bladder tumor resection was defined as 2 or more resections occurring within 60 days of diagnosis. Using multivariable models, we assessed the relationship between the use of restaging resection and cancer-specific survival. RESULTS: Restaging resection was performed in only 3064 (4.9%) of newly diagnosed bladder cancer patients, but was most common among those with high grade (7.7% vs 2.0% in low grade, P < .001) and stage (8.8% in T2 vs 2.8% in Ta/Tis, P < .001) disease. Compared to patients with muscle-invasive cancers who did not undergo restaging at diagnosis, restaging resection was associated with improved 5-year cancer-specific mortality among pathologically staged patients (20.4% vs 28.0%, P = .02), while clinically staged patients trended toward improved mortality (28.2% vs 31.9%, P = .07). CONCLUSION: Restaging transurethral resection for bladder cancer is relatively uncommon and associated with improved survival among patients with muscle invasive bladder cancer. Greater use of restaging warrants further investigation as a simple means of improving outcomes among patients suspected of having muscle invasive disease.

Understanding bladder cancer death: tumor biology versus physician practice.

BACKGROUND: To the authors' knowledge, the extent to which death from bladder cancer is attributable to tumor biology or physician practice patterns is unknown. For this reason, the relative importance of broadening indications for aggressive therapy has unclear implications. METHODS: Patients whose deaths were caused directly by bladder cancer were identified using institutional (n = 126 patients) and administrative (n = 6326 patients) data sources. By using implicit review (clinical data, 2001-2005) and explicit algorithms (Surveillance, Epidemiology, and End Results [SEER]-Medicare, 1992-2002), the authors estimated the proportion of potentially avoidable deaths from bladder cancer. RESULTS: After an implicit review of clinical data, 40 of 126 deaths (31.7%) were classified as potentially avoidable. Compared with those patients who were deemed unsalvageable, these patients generally presented with nonmuscle-invasive disease (80% vs 25.6%; P < .001), received multiple courses of intravesical therapy (32.5% vs 1.2%; P < .001), and had a more protracted course from diagnosis to aggressive treatment (median, 23 months vs 2 months; P < .001). An explicit review of claims data indicated that between 31.6% and 46.8% of the 6326 bladder cancer deaths identified in the SEER-Medicare data potentially were avoidable, depending on the survivorship threshold chosen. Patients whose deaths potentially were avoidable more commonly presented with nonmuscle-invasive disease (66.7% vs 24.7%; P < .0001) and lower grade disease (35.1% vs 15.1%; P < .0001). CONCLUSIONS: The greatest inroads into reducing death from bladder cancer likely hinge on earlier detection or improvement of systemic therapies. However, changing physician practice may translate into nontrivial reductions in bladder cancer mortality.

Cost comparison of radical retropubic and radical perineal prostatectomy: single institution experience.

OBJECTIVES: To perform a detailed comparison of the in-house hospital costs of patients undergoing radical perineal prostatectomy (RPP) and radical retropubic prostatectomy (RRP) performed with or without bilateral staging lymph node dissection (BPLND) for localized prostate cancer. METHODS: A retrospective cost review was done of a cohort of 402 consecutive radical prostatectomies performed at our institution during a 21-month period. The procedure was performed as RPP in 279 (69.4%) and RRP in 123 (30.6%) patients, of whom 10.4% and 61.8%, respectively, underwent BPLND under the same anesthesia. The hospital costs were evaluated for each patient using the categories of surgical, nursing, laboratory/transfusion, and pharmacy. Surgical costs were further subdivided into operating room, anesthesia, and recovery room costs. Univariate and multivariate statistical analyses were applied to identify predictors of procedure-related costs. RESULTS: The median hospital costs of patients undergoing RPP (7195 dollars, range 5052 dollars to 36,237 dollars) were substantially lower than those of patients undergoing RRP (9757 dollars, range 6935 dollars to 27,771 dollars; P = 0.001). The median costs for patients undergoing radical prostatectomy without BPLND were significantly lower in the RPP (7100 dollars, range 5052 dollars to 28,604 dollars) versus RRP (9169 dollars, range 6935 dollars to 16,705 dollars) patients (P = 0.001). The costs for RPP with BPLND (10,048 dollars, range 7529 dollars to 36,237 dollars) versus RRP with BPLND (9973 dollars, range 7658 dollars to 27,771 dollars) were not significantly different (P = 0.900). Patient age and nerve-preservation status did not significantly influence the procedure-related hospital costs. CONCLUSIONS: RPP may result in lower in-house costs per patient than RRP in those patients who do not require BPLND. Total hospital costs depend largely on the factors of operating room time, length of stay, and laboratory and transfusion requirements, which may vary among institutions.

Bilateral renal calculi: assessment of staged v synchronous percutaneous nephrolithotomy.

BACKGROUND AND PURPOSE: Percutaneous stone removal has replaced open renal surgery and has become the treatment of choice for large or complex renal calculi. However, patients with large bilateral stone burdens still present a challenge. Simultaneous bilateral percutaneous nephrolithotomy (PCNL) has been demonstrated to be a well-tolerated, safe, cost-effective, and expeditious treatment. We present what is, to our knowledge, the first large retrospective series comparing synchronous and asynchronous bilateral PCNL. PATIENTS AND METHODS: A chart review was performed on 26 patients undergoing 57 PCNLs for bilateral renal calculi over a 7-year period. Seven patients received synchronous PCNL (same anesthesia; Group 1), and 19 patients underwent asynchronous PNL (procedures separated by 1-3 months; Group 2). Complete surgical and hospital records were available on all patients. The average stone burden for Group 1 was 8.03 cm(2) on the left and 9.18 cm(2) on the right v 10.1 cm(2) on the left and 14.23 cm(2) on the right for Group 2 (P> 0.05). Variables of interest included anesthesia time, operative time, blood loss, transfusion rates, length of hospital stay, and complication rates. Each variable was evaluated per operation and per renal unit. Follow-up imaging with stone assessment was available on 20 patients. RESULTS: Group 1 required 1.14 access tracts per renal unit to attempt complete clearance of the targeted stones v 1.88 tracts per renal unit in Group 2 (P> 0.05). The average operative time per renal unit was significantly less in Group 1 (83 minutes) than in Group 2 (168.5 minutes) (P< 0.0001), as was blood loss (178.5 mL v 307.4 mL, respectively; P= 0.02). However, blood loss per operation was similar at 357 mL in Group 1 and 282 mL in Group 2. Comparable transfusion rates of 28.6% and 36.8%, respectively, were noted. Forty percent of the patients in Group 1 were completely stone free compared with 36% of the patients in Group 2; however, an additional 50% and 57%, respectively, had residual stone burden <4 mm (P> 0.05). Complications occurred in 2 of 7 operations (28%) in Group 1 and 8 of 42 operations (19%) in Group 2. The total length of hospital stay was nearly doubled for patients undergoing staged PCNL (P= 0.0005). CONCLUSIONS: These results demonstrate similar stone-free rates, blood loss per operation, and transfusion rates for simultaneous and staged bilateral PCNL. The reduced total operative time, hospital stay, and total blood loss, along with the requirement for only one anesthesia, makes synchronous bilateral PCNL an attractive option for select individuals. However, in patients with larger, less easily accessible stones, excessive bleeding may be encountered more frequently on the first side, thereby delaying management of the second side to a later date. Synchronous bilateral PCNL should be considered in patients in whom the first stage of stone removal is accomplished quickly and safely.

A longitudinal assessment of bowel related symptoms and fecal incontinence following radical perineal prostatectomy.

PURPOSE: Recent studies have suggested an increased incidence of fecal incontinence following radical perineal prostatectomy. We provide a prospective and longitudinal assessment of bowel related symptoms of patients undergoing radical perineal prostatectomy. MATERIALS AND METHODS: A total of 78 patients who underwent radical perineal prostatectomy between January 1 and December 31, 2001 and had a minimal followup of 6 months were included in the analysis. Patient information was obtained from the chart and the bowel domain specific questions of a validated quality of life questionnaire, the Expanded Prostate Cancer Index Composite. The questionnaire was administered to the candidates preoperatively, at 4 weeks following surgery and subsequently at 3-months intervals. A mean bowel function, bother and summary health related quality of life score was calculated at each interval. The duration of new or worsened symptoms with respect to baseline was evaluated using Kaplan-Meier analysis. RESULTS: Symptoms of involuntary stool leakage and rectal urgency were reported by 11.5% (9 of 78) and 19.2% (15) of patients preoperatively. While all bowel related symptoms transiently increased following surgery, rectal urgency was the most persistent symptom, yet normalized in more than 90% of patients within 9 1/2 months. Compared to individual baseline 15.4%, 7.7%, 5.1% and 3.9% of patients reported worsened symptoms of fecal incontinence after 3, 6, 9 and 12 months, respectively. In the subset of 69 patients who denied preoperative fecal incontinence the incidence of involuntary stool leakage was 2.9% by 12 months following radical perineal prostatectomy. Of 10 patients 9 recovered individual health related quality of life score by 6 months after prostatectomy. CONCLUSIONS: Longitudinal assessment of self-reported questionnaire data suggests that fecal incontinence and bowel related symptoms are more prevalent following radical perineal prostatectomy compared to baseline, yet resolve in the majority of patients with time in the early postoperative period.

Assessment of stricture formation with the ureteral access sheath.

OBJECTIVES: To analyze the long-term incidence of ureteral stricture formation in a series of patients in whom a new-generation ureteral access sheath was used. A new generation of ureteral access sheaths has been developed to facilitate ureteroscopic procedures. However, some have questioned their safety and whether the device might cause significant ureteral trauma. METHODS: Between September 1999 and July 2001, 150 consecutive ureteroscopic procedures with adjunctive use of an access sheath were performed. A retrospective chart review to April 2002 was done. Of the 150 patients, 130 underwent ureteroscopy for ureteral stones. Patients who underwent endoureterotomy or treatment of transitional cell carcinoma were excluded from this analysis. Sixty-two patients had follow-up greater than 3 months and were included in the analysis. Overall, 71 ureteroscopic procedures were performed, with 9 patients undergoing multiple procedures. Ninety-two percent of the patients had pathologic findings above the iliac vessels. The average patient age was 45.3 years (range 17 to 76), and 70% and 30% of the patients were male and female, respectively. The mean clinical follow-up was 332 days (range 95 to 821), and follow-up imaging was performed within 3 months after ureteroscopy in all patients. RESULTS: The 10/12F access sheath was used in 8 ureteroscopic procedures (11.2%), the 12/14F access sheath in 56 (78.9%), and the 14/16F access sheath in 7 (9.8%). One stricture was identified on follow-up imaging of 71 procedures performed, for an incidence of 1.4%. The patient developed the stricture at the ureteropelvic junction after multiple ureteroscopic procedures to manage recurrent struvite calculi. The access sheath did not appear to be a contributing factor. CONCLUSIONS: The results of our series indicate that the ureteral access sheath is safe and beneficial for routine use to facilitate flexible ureteroscopy. However, awareness of the potential ischemic effects with the use of unnecessarily large sheaths for long periods in patients at risk of ischemic injury should be considered. We advocate the routine use of the device for most flexible ureteroscopic procedures proximal to the iliac vessels.