Publications by authors named "Aaron M Potretzke"

51 Publications

Predictors of Locoregional Recurrence and Delineation of Adjuvant Radiation Therapy Fields for Patients with Upper Tract Urothelial Carcinoma Receiving Nephroureterectomy.

Pract Radiat Oncol 2021 Feb 23. Epub 2021 Feb 23.

Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota. Electronic address:

Background: and Purpose: To identify factors predictive of locoregional recurrence (LRR) in upper tract urothelial carcinoma (UTUC) treated with nephroureterectomy (NU) and propose adjuvant radiation therapy (ART) fields.

Materials And Methods: Clinical and pathologic variables for patients receiving NU for UTUC between 1995 and 2009 were analyzed for associations with outcomes. Sites of LRR from all patients with available imaging (n=39) were contoured on CT image sets of patients with representative anatomy, and ART fields were proposed based on these distributions.

Results: A total of 279 patients with a median follow-up of 13.0 years were analyzed. The 5-year cumulative incidence of LRR was 16.7% (95% CI 12.2-21). Pathologic risk factors (PRF) associated with increased risk of LRR included: tumor in both the renal pelvis and ureter, T-stage≥2, lymph node involvement, grade 3 histology, and positive surgical margins (p<0.05). Patients with an increasing number of PRF had a significantly greater risk of LRR. The 5-year cumulative incidence estimates of LRR were 5.3% (1.8-16.0), 15.6% (9.5-25.7), and 43.9% (31.1-62.1) for those with 1, 2, and ≥3 PRF, respectively. ART fields covering the renal fossa and retroperitoneal lymph nodes from the superior border of L1 through the aortic bifurcation would encompass all sites of LRR for 33 of 46 (72%) patients. Non-LRR bladder and distant failure (DF) occurred in 101 (36.2%) and 73 (26.2%) of patients, respectively. The 5-year cumulative incidence estimate of DF was 22.5% (17.4-27.3).

Conclusions: In patients receiving NU for UTUC, LRR is significantly increased in patients with two or more PRF. These data provide clinically valuable insight into the selection of candidates for ART and design of ART fields.
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http://dx.doi.org/10.1016/j.prro.2021.02.005DOI Listing
February 2021

Robot-assisted partial nephrectomy is safe and effective for complex renal masses when performed by experienced surgeons.

Transl Androl Urol 2020 Dec;9(6):2474-2478

Department of Urology, Mayo Clinic, Rochester, Minnesota, USA.

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http://dx.doi.org/10.21037/tau-20-865DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7807336PMC
December 2020

Grading Chromophobe Renal Cell Carcinoma: Evidence for a Four-tiered Classification Incorporating Coagulative Tumor Necrosis.

Eur Urol 2021 Feb 7;79(2):225-231. Epub 2020 Nov 7.

Department of Urology, Mayo Clinic, Rochester, MN, USA. Electronic address:

Background: Although grading systems have been proposed for chromophobe renal cell carcinoma (ChRCC), including a three-tiered system by Paner et al (Paner GP, Amin MB, Alvarado-Cabrero I, et al. A novel tumor grading scheme for chromophobe renal cell carcinoma: prognostic utility and comparison with Fuhrman nuclear grade. Am J Surg Pathol 2010;34:1233-40), none have gained clinical acceptance, and the World Health Organization (WHO) currently recommends against grading ChRCC.

Objective: To validate a previously published grading scheme and propose a scheme that includes tumor necrosis.

Design, Setting, And Participants: A total of 266 patients who underwent nephrectomy for nonmetastatic ChRCC between 1970 and 2012 were reviewed for ChRCC grade according to the Paner system and coagulative tumor necrosis.

Outcome Measurements And Statistical Analysis: Associations with cancer-specific survival (CSS) were evaluated using Cox proportional hazard regression models and summarized with hazard ratios (HRs).

Results And Limitations: Twenty-nine patients died from RCC; the median follow-up was 11.0 (interquartile range 7.9-15.9) yr. ChRCC grade according to the Paner system was significantly associated with CSS, including the difference in outcome between grade 1 and 2 tumors. Among patients with grade 2 tumors, the presence of tumor necrosis helped delineate patients with worse CSS. As such, the Paner system was expanded to four tiers separating grade 2 into those with and without tumor necrosis. HRs for associations of the proposed grade 2, 3, and 4 tumors with CSS were 4.63 (p=0.007), 17.8 (p<0.001), and 20.9 (p<0.001), respectively. The study is limited by the lack of multivariable analysis including additional pathologic features.

Conclusions: The expansion of a previously reported ChRCC grading system from three to four tiers by the inclusion of tumor necrosis helps further delineate patient outcome and can, therefore, enhance patient counseling following surgery. It also aligns the number of ChRCC grades with the WHO/International Society of Urologic Pathology four-tiered grading systems for clear cell and papillary RCC.

Patient Summary: Chromophobe renal cell carcinoma is the third most common type of renal cancer, and unlike other renal cancers, there is no accepted prognostic grading system. In this study, we found that a grading system that included a pathologic feature of tumor necrosis could better define outcomes for patients with chromophobe renal cell carcinoma.
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http://dx.doi.org/10.1016/j.eururo.2020.10.007DOI Listing
February 2021

Detection of distal ureteral stones in pregnancy using transvaginal ultrasound.

J Ultrasound 2020 Jul 14. Epub 2020 Jul 14.

Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN, 55902, USA.

Aims: To determine the performance of transvaginal ultrasound for the visualization of distal ureteral stones in pregnant patients with renal colic and to evaluate the diagnostic value of secondary findings suggestive of obstructing ureteral stone disease.

Methods: We retrospectively identified 129 pregnant patients with a total of 142 encounters with both abdominal and transvaginal ultrasound. Ultrasound images for each patient were reviewed recording the presence of stone with location, hydronephrosis, resistive indices (RI), and status of the ureteral jets. Patients were subcategorized into two groups based on the visualization of distal ureteral stone.

Results: The transvaginal technique identified 94% (N = 16/17) of sonographically detected stones in the distal ureter/urethra, while the transabdominal technique identified 29% (N = 5/17). The combined imaging for initial assessment of renal colic in pregnancy demonstrated a sensitivity of 89%, specificity 100%, and negative predictive value (NPV) of 98%. The frequency of hydronephrosis was statistically greater in the visualized stone group (94% vs 51%). Mean RI was identical in both groups however the delta RI was significantly elevated in those patients with distal ureteral stones with a mean delta RI value of 0.05. The rate of absence of ureteral jets was not statistically significant.

Conclusion: The present data would suggest a utility of transvaginal ultrasound for the evaluation of the pregnant patient with 94% of distal stones being detected transvaginal versus 29% transabdominally. Additionally, there was significantly increased hydronephrosis and elevated RIs in patients with distal ureteral stones.
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http://dx.doi.org/10.1007/s40477-020-00504-4DOI Listing
July 2020

Timing and distribution of early renal cell carcinoma recurrences stratified by pathological nodal status in M0 patients at the time of nephrectomy.

Int J Urol 2020 Jul 18;27(7):618-622. Epub 2020 May 18.

Departments of, Department of, Urology, Mayo Clinic, Rochester, Minnesota, USA.

Objectives: To evaluate the timing and distribution of first renal cell carcinoma metastasis after nephrectomy stratified by nodal status.

Methods: We evaluated patients treated with nephrectomy for sporadic, unilateral renal cell carcinoma between 1970 and 2011 who subsequently developed distant metastasis to three or fewer sites. Site-specific metastases-free 2-year survival rates were estimated using the Kaplan-Meier method. Associations of nodal status with time to metastasis were evaluated using multivariable Cox regression models.

Results: A total of 1049 patients met the inclusion criteria (135 pN1, 914 pN0/x patients). The median time to identification of first distant metastasis for pN1 patients was 0.4 years (interquartile range 0.2-1.1 years) versus 2.2 years (interquartile range 0.6-6.0 years) in pN0/x patients. The most common site of metastasis was to the lung, but this occurred earlier in pN1 patients (median 0.3 years vs 2.0 years). pN1 was associated with significantly lower site-specific 2-year metastases-free survival when compared with pN0/x for lung (37% vs 70%, P < 0.001), bone (63% vs 87%, P < 0.001), non-regional lymph nodes (60% vs 96%, P < 0.001) and liver metastases (79% vs 91%, P < 0.001). On multivariable analysis, pN1 status remained significantly associated with lung, bone, and non-regional lymph node (all P < 0.001) metastases, but it was no longer associated with liver metastases (P = 0.3).

Conclusions: pN1 nodal status in M0 patients treated with nephrectomy for renal cell carcinoma is associated with more frequent early metastasis to sites conferring poor prognosis when compared with pN0/x. Our findings highlight the importance of rigorous, early surveillance though the multimodal use of a comprehensive history, physical, laboratory and radiological studies, as outlined in societal guidelines.
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http://dx.doi.org/10.1111/iju.14261DOI Listing
July 2020

Predicting Adherent Perinephric Fat Using Preoperative Clinical and Radiological Factors in Patients Undergoing Partial Nephrectomy.

Eur Urol Focus 2019 Nov 1. Epub 2019 Nov 1.

Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA. Electronic address:

Background: The decision to perform a partial nephrectomy (PN) relies largely upon the complexity of the renal mass and its surrounding anatomy. The presence of adherent perinephric fat (APF) can increase surgical complexity and extend operative times. The accurate prediction of APF may improve surgical planning and aid in decision making for the surgical approach.

Objective: We sought to develop and externally validate a score that predicts APF based on preoperative clinical and radiological prognostic factors.

Design, Setting, And Participants: We retrospectively analyzed 495 consecutive patients who underwent open or minimally invasive PN. APF was defined as the presence of "dense," "adherent," or "sticky" perinephric fat at the time of dissection by the surgeon, and this did not require subcapsular dissection. Additionally, we analyzed an independent cohort of 285 patients for external validation.

Outcome Measurements And Statistical Analysis: A score model was developed using multivariate logistic regression analysis. Calibration of the fitted model was assessed graphically with a plot of the predicted versus the actual probability of APF, and discrimination was assessed by calculating the area under the receiver operating characteristic curve.

Results And Limitations: Of the 495 patients, 95 (19%) had APF. Patients with APF had longer operative (p=0.02) and arterial clamp (p=0.01) times than non-APF patients. On multivariate analyses, diabetes mellitus (p=0.009), posterior perinephric fat thickness (p<0.001), and perinephric stranding (p<0.001) were predictors of encountering APF in PN. A risk score ranging from 0 to 4 was developed based on these three variables to predict APF. The scoring system demonstrated good discrimination of 0.82 and 0.84 for the development and external validation cohorts, respectively.

Conclusions: The APF score can accurately predict the presence of APF in patients with a small renal mass who are planning to undergo PN. This score could aid in pre- and intraoperative planning and impact the surgical approach.

Patient Summary: The presence of "sticky" fat surrounding the kidney in patients undergoing partial nephrectomy has previously been linked to longer operative times, intraoperative complications, and surgical conversion. In our study, we found that this feature is more often presented in patients with diabetes mellitus, and thicker and more inflammatory fat on renal imaging. Based on these findings, we developed a risk score that can accurately predict this feature before surgery, in order to improve surgical planning and better counsel the patients.
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http://dx.doi.org/10.1016/j.euf.2019.10.007DOI Listing
November 2019

Percutaneous Image-guided Core Needle Biopsy for Upper Tract Urothelial Carcinoma.

Urology 2020 Jan 23;135:95-100. Epub 2019 Oct 23.

Department of Urology, Mayo Clinic, Rochester, MN. Electronic address:

Objective: To better understand the safety and diagnostic yield of percutaneous core-needle biopsy (PCNB) for upper tract urothelial carcinoma (UTUC).

Methods: Of 444 patients undergoing radical nephroureterectomy (RNU) for UTUC between 2009 and 2017 at our institution, 42 who had PCNB prior to RNU were identified for analysis. Endpoints included safety, diagnostic yield, and concordance with RNU pathology. PCNB specimens were deemed histologically concordant with RNU specimens for cases when cytologic evaluation of biopsy specimen and corresponding pathologic evaluation of RNU specimen both made a histologic diagnosis of urothelial carcinoma.

Results: Median tumor size was 3.8 cm (1.2-10.2 cm). All lesions arose from the pelvicalyceal system. CT-guidance was utilized in 52% (n = 22), and ultrasound-guidance in 48% (n = 20). Relative to RNU pathology, 95% of PCNBs demonstrated histologic concordance. Histologic grade was provided in 69% (n = 29) of PCNBs, with a 90% (n = 26) concordance with surgical pathology. Grades 1-2 and 3 complications occurred in 14.3% (n = 6) and 2.4% (n = 1), respectively. At a median follow-up of 28.2 months (range, 1.2-97.1 months) after biopsy, no cases of radiographic tract seeding were identified.

Conclusion: In our cohort of 42 patients undergoing RNU for UTUC, PCNB appeared a safe diagnostic tool with high histologic yield and grade concordance. With greater than 2 years of follow-up, no cases of tract seeding were identified.
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http://dx.doi.org/10.1016/j.urology.2019.10.005DOI Listing
January 2020

Author Reply.

Urology 2019 04;126:109

Division of Urologic Surgery, Washington University School of Medicine, St. Louis, MO.

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http://dx.doi.org/10.1016/j.urology.2018.11.055DOI Listing
April 2019

Comparing Off-clamp and On-clamp Robot-assisted Partial Nephrectomy: A Prospective Randomized Trial.

Urology 2019 04 16;126:102-109. Epub 2019 Jan 16.

Division of Urologic Surgery, Washington University School of Medicine, St. Louis, MO.

Objective: To determine whether performing robot-assisted partial nephrectomy without warm ischemia "off-clamp" results in favorable postoperative renal functional outcomes compared with the on-clamp method.

Methods: We conducted a prospective trial of 80 patients who underwent robot-assisted partial nephrectomy. They were randomized in a 1:1 ratio to undergo the procedure with renal artery clamping or without clamping. The groups were compared across demographics, operative information, perioperative outcomes, and postoperative renal function. We assessed renal function by estimated glomerular filtration rate and renal scintigraphy both preoperatively and at 3 months postoperatively.

Results: Patients in the on-clamp and off-clamp groups were similar in age, gender, body mass index, comorbidities, clinical tumor size, nephrometry score, and laterality. Off-clamp procedures were lengthier at an average 178.0 minutes vs 156.0 minutes for on-clamp (P = .011). Estimated blood loss, rates of pelvicalyceal repair, postoperative complications, and positive margins were not different. At a median 3-month follow-up, no significant differences were seen in change in postoperative estimated glomerular filtration rate or percent split renal function between both groups.

Conclusion: In this prospective study, off-clamp robot-assisted partial nephrectomy resulted in similar perioperative outcomes compared with the on-clamp technique. No benefit was demonstrated in the preservation of renal function. Urologists may safely employ either an on-clamp or off-clamp strategy depending on surgeon preference and patient-specific factors including baseline renal insufficiency, multiple masses, or solitary kidney.
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http://dx.doi.org/10.1016/j.urology.2018.11.053DOI Listing
April 2019

The Probability of Aggressive Versus Indolent Histology Based on Renal Tumor Size: Implications for Surveillance and Treatment.

Eur Urol 2018 10 13;74(4):489-497. Epub 2018 Jul 13.

Department of Urology, Mayo Clinic, Rochester, MN, USA. Electronic address:

Background: While the probability of malignant versus benign histology based on renal tumor size has been described, this alone does not sufficiently inform decision-making in the modern era since indolent malignant tumors can be managed with active surveillance.

Objective: To characterize the probability of aggressive versus indolent histology based on radiographic tumor size.

Design, Setting, And Participants: We evaluated patients who underwent radical or partial nephrectomy at Mayo Clinic for a pT1-2, pNx/0, M0 solid renal tumor between 1990 and 2010. Pathology was reviewed by one genitourinary pathologist. High-grade clear-cell renal cell carcinoma (RCC), high-grade papillary RCC, collecting duct RCC, translocation-associated RCC, hereditary leiomyomatosis RCC, unclassified RCC, and malignant non-RCC tumors were all considered aggressive, as well as any tumors demonstrating coagulative necrosis (except low-grade papillary RCC) or sarcomatoid differentiation. The remaining benign and malignant tumors were considered indolent.

Outcome Measurements And Statistical Analysis: Cancer-specific survival (CSS) was estimated using the Kaplan-Meier method. Logistic regression models were used to estimate the probability of malignant and aggressive histology based on tumor size. Sex-stratified analyses were also performed.

Results And Limitations: Of the 2650 patients included, there were 1860 patients with indolent tumors (300 benign; 1560 malignant) and 790 with aggressive tumors. The 10-yr CSS was 96% for indolent malignant tumors and 81% for aggressive malignant tumors. The predicted percentages of any malignant histology as well as aggressive histology increased with tumor size. Specifically, 2cm, 3cm, and 4cm tumors have an estimated 84%, 87%, and 88% likelihood of malignancy, respectively, and an 18%, 24%, and 29% likelihood of aggressive histology, respectively. For any given tumor size, men had a greater chance of aggressive histology than women. Potential limitations of this observational surgical cohort include selection bias.

Conclusions: We present tumor size-based estimates of the probability of aggressive histology for renal masses. This information should be useful for initial patient counseling and management.

Patient Summary: Active surveillance is an option for kidney masses, even if they are malignant. Beyond knowing whether the mass is benign or cancer, it is important to know whether or not it is an aggressive tumor. This study presents tumor size-specific and sex-specific estimates of the probability of cancer overall and aggressive cancer among patients with a kidney mass in order to aid with initial decision-making.
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http://dx.doi.org/10.1016/j.eururo.2018.06.003DOI Listing
October 2018

Catheterization alters bladder ecology to potentiate infection of the urinary tract.

Proc Natl Acad Sci U S A 2017 10 25;114(41):E8721-E8730. Epub 2017 Sep 25.

Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110;

Methicillin-resistant (MRSA) is an emerging cause of catheter-associated urinary tract infection (CAUTI), which frequently progresses to more serious invasive infections. We adapted a mouse model of CAUTI to investigate how catheterization increases an individual's susceptibility to MRSA UTI. This analysis revealed that catheterization was required for MRSA to achieve high-level, persistent infection in the bladder. As shown previously, catheter placement induced an inflammatory response resulting in the release of the host protein fibrinogen (Fg), which coated the bladder and implant. Following infection, we showed that MRSA attached to the urothelium and implant in patterns that colocalized with deposited Fg. Furthermore, MRSA exacerbated the host inflammatory response to stimulate the additional release and accumulation of Fg in the urinary tract, which facilitated MRSA colonization. Consistent with this model, analysis of catheters from patients with -positive cultures revealed colocalization of Fg, which was deposited on the catheter, with Clumping Factors A and B (ClfA and ClfB) have been shown to contribute to MRSA-Fg interactions in other models of disease. We found that mutants in had significantly greater Fg-binding defects than mutants in in several in vitro assays. Paradoxically, only the ClfB strain was significantly attenuated in the CAUTI model. Together, these data suggest that catheterization alters the urinary tract environment to promote MRSA CAUTI pathogenesis by inducing the release of Fg, which the pathogen enhances to persist in the urinary tract despite the host's robust immune response.
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http://dx.doi.org/10.1073/pnas.1707572114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5642702PMC
October 2017

Off-clamp robot-assisted partial nephrectomy does not benefit short-term renal function: a matched cohort analysis.

J Robot Surg 2018 Sep 31;12(3):401-407. Epub 2017 Aug 31.

Division of Urologic Surgery, Washington University School of Medicine, 4960 Children's Place, Campus Box 8242, St. Louis, MO, 63110, USA.

In the interest of renal functional preservation, partial nephrectomy has supplanted radical nephrectomy as the preferred treatment for T1 renal masses. This procedure usually involves the induction of renal warm ischemia by clamping the hilar vessels prior to tumor excision. Performing robot-assisted partial nephrectomy (RAPN) "off-clamp" can theoretically prevent renal functional loss associated with warm ischemia. We describe our institutional experience and compare perioperative and renal functional outcomes using a propensity score matched cohort. We conducted a retrospective comparison from a prospectively maintained database of all patients who underwent RAPN from 2009 to 2015. Of those patients, 143 underwent off-clamp RAPN. Fifty off-clamp RAPN patients were propensity score matched with fifty clamped RAPN patients based on renal function, tumor size, and R.E.N.A.L. nephrometry score. The cohorts were compared across demographics, operative information, perioperative outcomes, and renal functional outcomes. For all off-clamp RAPN patients, mean nephrometry score was 7.1, mean estimated blood loss (EBL) was 236.9 mL, perioperative complication rate was 7.7%, and mean decrease in estimated glomerular filtration rate (eGFR) was 7.1% at a median follow-up of 9.2 months. In the propensity score matched cohorts, off-clamp RAPN resulted in a shorter mean operative time (172.0 versus 196.0 min, p = 0.025) and a lower mean EBL (179.7 versus 283.2 mL, p = 0.046). A lower complication rate of 6.0% in the off-clamp group compared with 20.0% in the clamped group approached significance (p = 0.071). Mean preoperative eGFR was similar in both cohorts. Importantly, there was no significant difference in decrease in eGFR between the clamped cohort (9.8%) and off-clamp cohort (11.9%) at a median follow-up of 9.0 months (p = 0.620). Off-clamp RAPN did not result in improved renal functional preservation in our experience. Surprisingly, the off-clamp cohort experienced lower intraoperative blood loss, shorter operative times, and fewer complications.
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http://dx.doi.org/10.1007/s11701-017-0745-6DOI Listing
September 2018

Trends in the Management of Small Renal Masses: A Survey of Members of the Endourological Society.

J Kidney Cancer VHL 2017 20;4(3):10-19. Epub 2017 Jul 20.

Division of Urologic Surgery, Washington University School of Medicine, St. Louis, MO, USA.

Treatment modalities for small renal masses (SRMs) include open or minimally invasive radical or partial nephrectomy, and laparoscopic or percutaneous ablations. Members of the Endourological Society were surveyed to evaluate how practitioner and clinical practice characteristics may be associated with the management of SRMs over time. The survey assessed characteristics of urologists (recency of residency and fellowship training, clinical practice type and location, and treatment modalities available) and their management of SRMs over the past year and over the course of the year 5 years prior. Of the 1495 surveys e-mailed, there were 129 respondents (8.6%). Comparing the past year to 5 years prior, there was increasing utilization of robotic partial nephrectomy (p < 0.001) and robotic radial nephrectomy (p = 0.031). In contrast, there was decreasing utilization of open partial nephrectomy (p < 0.001), open radical nephrectomy (p = 0.039), laparoscopic partial nephrectomy (p = 0.002), and laparoscopic radical nephrectomy (p = 0.041). Employment of laparoscopic ablation decreased (p = 0.001), but that of percutaneous ablation did not change significantly. For masses treated with image-guided therapy, there was increasing utilization of microwave ablation (p = 0.008) and decreasing usage of radiofrequency ablation (p = 0.002). Future studies should focus on the most effective treatment modalities based on provider, patient, and tumor characteristics.
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http://dx.doi.org/10.15586/jkcvhl.2017.82DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5519769PMC
July 2017

Retroperitoneal access for robotic renal surgery.

Int Braz J Urol 2018 Jan-Feb;44(1):200-201

Washington University School of Medicine, Division of Urology, Saint Louis, Missouri, USA.

Introduction And Objective: Retroperitoneal access for robotic renal surgery is an effective alternative to the commonly used transperitoneal approach. We describe our contemporary experience and technique for attaining retroperitoneal access.

Materials And Methods: We outline our institutional approach to retroperitoneal access for the instruction of urologists at the beginning of the learning curve. The patient is placed in the lateral decubitus position. The first incision is made just inferior to the tip of the twelfth rib as described by Hsu, et al. After the lumbodorsal fascia is traversed, the retroperitoneal space is dilated with a round 10 millimeter AutoSutureTM (Covidien, Mansfield, MA) balloon access device. The following trocars are used: A 130 millimeter KiiR balloon trocar (Applied Medical, Rancho Santa Margarita, CA), three robotic, and one assistant. Key landmarks for the access and dissection are detailed.

Results: 177 patients underwent a retroperitoneal robotic procedure from 2007 to 2015. Procedures performed include 158 partial nephrectomies, 16 pyeloplasties, and three radical nephrectomies. The robotic fourth arm was utilized in all cases. When compared with the transperitoneal approach, the retroperitoneal approach was associated with shorter operative times and decreased length of stay (1). Selection bias and surgeon preference accounted for the higher proportion of patients who underwent partial nephrectomy off-camp via the retroperitoneal approach.

Conclusions: Retroperitoneal robotic surgery may confer several advantages. In patients with previous abdominal surgery or intra-abdominal conditions, the retroperitoneum can be safely accessed while avoiding intraperitoneal injuries. The retroperitoneum also provides a confined space that may minimize the sequelae of potential complications including urine leak. Moreover, at our institution, retroperitoneal robotic surgery is associated with shorter operative times and a decreased length of stay when compared with the transperitoneal approach (2). In selected patients, the retroperitoneal approach is a viable alternative to the transperitoneal approach for a variety of renal procedures.
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http://dx.doi.org/10.1590/S1677-5538.IBJU.2016.0633DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5815554PMC
June 2018

Patient and nonradiographic tumor characteristics predicting lipid-poor angiomyolipoma in small renal masses: Introducing the BEARS index.

Investig Clin Urol 2017 07 27;58(4):235-240. Epub 2017 Jun 27.

Division of Urologic Surgery, Washington University School of Medicine, St. Louis, MO, USA.

Purpose: To create a simple model using clinical variables for predicting lipid-poor angiomyolipoma (AML) in patients with small renal masses presumed to be renal cell carcinoma (RCC) from preoperative imaging.

Materials And Methods: A series of patients undergoing partial nephrectomy (PN) for renal masses ≤4 cm was identified using a prospectively maintained database. Patients were excluded if standard preoperative imaging was not consistent with RCC. Chi square and Mann-Whitney U analyses were used to evaluate differences in characteristics between patients with AML and other types of pathology. A logistic regression model was constructed for multivariable analysis of predictors of lipid-poor AML.

Results: A total of 730 patients were identified that underwent PN for renal masses ≤4 cm between 2007-2015, including 35 with lipid-poor AML and 620 with RCC. In multivariable analysis, the following features predicted AML: female sex (odds ratio, 6.89; 95% confidence interval, 2.35-20.92; p<0.001), age <56 years (2.84; 1.21-6.66; p=0.02), and tumor size <2 cm (5.87; 2.70-12.77; p<0.001). Sex, age, and tumor size were used to construct the BEnign Angiomyolipoma Renal Susceptibility (BEARS) index with the following point values for each particular risk factor: female sex (2 points), age <56 years (1 point), and tumor size <2 cm (2 points). Within the study population, the BEARS index distinguished AML from malignant lesions with an area under the curve of 0.84.

Conclusions: Young female patients with small tumors are at risk for having lipid-poor AML despite preoperative imaging consistent with RCC. Identification of these patients may reduce the incidence of unnecessary PN for benign renal lesions.
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http://dx.doi.org/10.4111/icu.2017.58.4.235DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5494346PMC
July 2017

Lymphoepithelioma-like carcinoma of the ureter: a rare presentation, synchronous with conventional urothelial carcinoma.

Can J Urol 2017 Feb;24(1):8673-8675

Division of Urologic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA.

Lymphoepithelioma-like carcinoma (LELC) is a rare finding in the upper urinary tract. The presenting clinical findings mimic those of other more common upper-tract tumors, such as urothelial carcinoma. Preoperative imaging has not been shown to reliably predict the diagnosis of LELC. This tumor can be misdiagnosed as a reactive inflammatory lesion or lymphoma if the proper immunohistochemical stains for cytokeratin are not used.
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February 2017

Validation of preoperative variables and stratification of patients to help predict benefit of cytoreductive nephrectomy in the targeted therapy ERA.

Int Braz J Urol 2017 May-Jun;43(3):432-439

Washington University School of Medicine, Division of Urology, St. Louis, Missouri, USA.

Objectives: To further elucidate which patients with metastatic renal cell carcinoma (mRCC) may benefit from cytoreductive nephrectomy (CN) before targeted therapy (TT), and to assess the overall survival of patients undergoing CN and TT versus TT alone.

Materials And Methods: We identified 88 patients who underwent CN at our institution prior to planned TT and 35 patients who received TT without undergoing CN. Preoperative risk factors described in the literature were assessed in our patient population (serum albumin, liver metastasis, symptomatic metastasis, clinical ≥T3 disease, retroperitoneal and supradiaphragmatic lymphadenopathy). Patients were stratified by number of pretreatment risk factors and overall survival (OS) was compared.

Results: TT patients had significantly more risk factors compared to CN patients (3.06 vs. 2.11, p<0.01). Patients who received TT alone had median OS of 5.8 months. All but one patient receiving TT alone had two or more risk factors. A comparison of the CN and TT groups was performed by constructing Kaplan-Meier curves. There was no significant difference in median OS for those patients with exactly two risk factors (447 vs. 389 days, p=0.24), and those with three or more risk factors (184 vs. 155 days, p=0.87).

Conclusions: Using previously described pretreatment risk factors we found that patients with two or more risk factors derived no significant survival advantage from CN in the TT era. These risk factors should be incorporated in the assessment of patients for CN.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5462133PMC
http://dx.doi.org/10.1590/S1677-5538.IBJU.2015.0118DOI Listing
October 2017

Partial Nephrectomy for Presumed Renal-Cell Carcinoma: Incidence, Predictors, and Perioperative Outcomes of Benign Lesions.

J Endourol 2017 04 3;31(4):412-417. Epub 2017 Feb 3.

1 Department of Surgery, Division of Urologic Surgery, Washington University School of Medicine , St. Louis, Missouri.

Background: The aim of this study was to investigate the incidence of benign histology after partial nephrectomy (PN) in patients with presumed malignancy from preoperative imaging. Furthermore, preoperative predictors of benign lesions and perioperative outcomes were also assessed.

Methods: A series of patients undergoing PN for renal masses was identified using a prospectively maintained database. Patients were excluded for known genetic conditions, if more than one renal mass was resected, or if standard preoperative imaging was not suspicious for renal-cell carcinoma (RCC). Differences in characteristics between patients with benign and malignant pathology were assessed.

Results: A total of 916 patients were identified who underwent PN between 2007 and 2015, including 129 (14.1%) patients with a final diagnosis of benign disease. The most common types of benign pathology were oncocytoma (n = 66, 51.2%), angiomyolipoma (n = 37, 28.7%), and complex cysts (n = 10, 7.8%). Low body mass index (BMI) [0.96 (0.92-0.99) p = 0.02], low R.E.N.A.L. score [0.86 (0.76-0.96) p = 0.007], and low preoperative creatinine [0.37 (0.14-0.91) p = 0.04] predicted benign histology in multivariate analysis. Tumor size was a significant predictor in additional modeling [0.81 (0.69-0.94) p = 0.008]. Patients with benign histology had significantly shorter operative times (p < 0.001) and less estimated blood loss (p < 0.001), and there was no difference in complication (p = 0.93) or blood transfusion (0.24) rates.

Conclusions: In this study, the rate of benign pathology after PN for presumed RCC is 14.1%. BMI, R.E.N.A.L. score, and preoperative creatinine are predictive of benign histology, but the ability of different variables to predict benign lesions may be influenced by the distribution of benign tumor subtypes, reflecting potential unidentified selection bias.
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http://dx.doi.org/10.1089/end.2016.0667DOI Listing
April 2017

Computed Tomography and Magnetic Resonance Findings of Fat-Poor Angiomyolipomas.

J Endourol 2017 02 3;31(2):119-128. Epub 2017 Jan 3.

3 Mallinckrodt Institute of Radiology, Washington University School of Medicine , St. Louis, Missouri.

Introduction: Approximately 5% of angiomyolipomas (AMLs) are classified as "fat poor" due to lack of visually detectable fat on imaging, making them difficult to distinguish from renal cell carcinoma. Recent investigations have proposed CT and MR imaging features suggestive of fat-poor AML (fp-AML). Herein, we determined the frequency of these features in a cohort of fp-AMLs by retrospective review of preoperative imaging.

Methods: A pathology database query from January 2005 to August 2013 identified 49 renal specimens of AML with available imaging. A retrospective review of all CT and MR images of these 49 cases was conducted. Cases with visually detectable fat on imaging were excluded.

Results: A total of 26 fp-AMLs were identified. Thirteen lesions had available unenhanced CT images, of which eight (62%) were hyperdense compared to the adjacent renal parenchyma, while five (38%) were isodense. Twenty lesions had enhanced CT images: 14 (70%) and 6 (30%) with homogeneous and heterogeneous enhancement, respectively. Of the nine lesions with enhanced MR sequences, five (56%) were homogeneously enhancing, and four (44%) were heterogeneously enhancing. Eight of nine (89%) lesions had hypointense signal intensity (SI) on T2-weighted MR sequences, while one (11%) had hyperintense SI. None of the eight lesions displayed a decrease in signal on fat-suppressed sequences.

Conclusions: In this study, we confirmed common imaging features of fp-AML: high attenuation on unenhanced CT sequences, homogeneous enhancement on CT, and hypointensity on T2-weighted MR. When these features are present, a renal mass biopsy may be prudent.
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http://dx.doi.org/10.1089/end.2016.0219DOI Listing
February 2017

Is extended preoperative antibiotic prophylaxis for high-risk patients necessary before percutaneous nephrolithotomy?

Investig Clin Urol 2016 11 24;57(6):417-423. Epub 2016 Oct 24.

Division of Urology, Washington University School of Medicine, Saint Louis, MO, USA.

Purpose: The goal of this study was to compare the rate of systemic inflammatory response syndrome (SIRS) in high-risk patients undergoing percutaneous nephrolithotomy (PCNL) between patients who received 7, 2, or 0 days of preoperative antibiotics.

Materials And Methods: We retrospectively reviewed a series of consecutive PCNLs performed at our institution. Patients with infected preoperative urine cultures were excluded. High-risk patients were defined as those with a history of previous urinary tract infection (UTI), hydronephrosis, or stone size ≥2 cm. Patients were treated with 7, 2, or 0 days of preoperative antibiotic prophylaxis prior to PCNL. All patients received a single preoperative dose of antibiotics within 60 minutes of the start of surgery. Fisher exact test was used to compare the rate of SIRS by preoperative antibiotic length.

Results: Of the 292 patients identified, 138 (47.3%) had sterile urine and met high-risk criteria, of which 27 (19.6%), 39 (28.3%), and 72 (52.2%) received 7, 2, and 0 days of preoperative antibiotics, respectively. The 3 groups were similar in age, sex, and duration of surgery (p>0.05). There was no difference in the rate of SIRS between the groups, with 1 of 27 (3.7%), 2 of 39 (5.1%) and 3 of 72 patients (4.2%) meeting criteria in the 7, 2, and 0 days antibiotic groups (p=~1).

Conclusions: Extended preoperative antibiotic prophylaxis was not found to reduce the risk of SIRS after PCNL in our institutional experience of high-risk patients. For these patients, a single preoperative dose of antibiotics is sufficient.
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http://dx.doi.org/10.4111/icu.2016.57.6.417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5109791PMC
November 2016

Off-clamp robotic-assisted partial nephrectomy.

Int Braz J Urol 2016 Sep-Oct;42(5):1044-1045

Division of Urologic Surgery, Washington University, St. Louis, Missouri, USA.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066907PMC
http://dx.doi.org/10.1590/S1677-5538.IBJU.2015.0386DOI Listing
June 2017

Metastatic Granulosa Cell Tumor of the Testis: Clinical Presentation and Management.

Case Rep Urol 2016 15;2016:9016728. Epub 2016 May 15.

Division of Urologic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA.

Granulosa cell tumors (GCTs) of the testis are rare sex cord-stromal tumors that are present in both juvenile and adult subtypes. While most adult GCTs are benign, those that present with distant metastases manifest a grave prognosis. Treatments for aggressive GCTs are not well established. Options that have been employed in previous cases include retroperitoneal lymph node dissection (RPLND), radiation, chemotherapy, or a combination thereof. We describe the case of a 57-year-old man who presented with a painless left testicular mass and painful gynecomastia. Serum tumor markers (alpha fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase) and computed tomography of the chest and abdomen were negative. The patient underwent left radical orchiectomy. Immunohistochemical staining was consistent with a testicular GCT. He underwent a left-template laparoscopic RPLND which revealed 2/19 positive lymph nodes. Final pathological stage was IIA. He remains free of disease 32 months after surgery.
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http://dx.doi.org/10.1155/2016/9016728DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4884594PMC
June 2016

Transmesenteric robot-assisted pyeloplasty for ureteropelvic junction obstruction in horseshoe kidney.

Int Braz J Urol 2016 May-Jun;42(3):626-7

Urology Academic Practice, Cedars-Sinai Medical Center, Los Angeles, CA, USA.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4920586PMC
http://dx.doi.org/10.1590/S1677-5538.IBJU.2015.0315DOI Listing
June 2017

Electronic nutritional intake assessment in patients with urolithiasis: A decision impact analysis.

Investig Clin Urol 2016 05 10;57(3):196-201. Epub 2016 May 10.

Urology Academic Practice, Cedars-Sinai Medical Center, Los Angeles, CA, USA.

Purpose: To evaluate a physician's impression of a urinary stone patient's dietary intake and whether it was dependent on the medium through which the nutritional data were obtained. Furthermore, we sought to determine if using an electronic food frequency questionnaire (FFQ) impacted dietary recommendations for these patients.

Materials And Methods: Seventy-six patients attended the Stone Clinic over a period of 6 weeks. Seventy-five gave consent for enrollment in our study. Patients completed an office-based interview with a fellowship-trained endourologist, and a FFQ administered on an iPad. The FFQ assessed intake of various dietary components related to stone development, such as oxalate and calcium. The urologists were blinded to the identity of patients' FFQ results. Based on the office-based interview and the FFQ results, the urologists provided separate assessments of the impact of nutrition and hydration on the patient's stone disease (nutrition impact score and hydration impact score, respectively) and treatment recommendations. Multivariate logistic regressions were used to compare pre-FFQ data to post-FFQ data.

Results: Higher FFQ scores for sodium (odds ratio [OR], 1.02; p=0.02) and fluids (OR, 1.03, p=0.04) were associated with a higher nutritional impact score. None of the FFQ parameters impacted hydration impact score. A higher FFQ score for oxalate (OR, 1.07; p=0.02) was associated with the addition of at least one treatment recommendation.

Conclusions: Information derived from a FFQ can yield a significant impact on a physician's assessment of stone risks and decision for management of stone disease.
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http://dx.doi.org/10.4111/icu.2016.57.3.196DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4869568PMC
May 2016

Diagnostic Utility of Selective Upper Tract Urinary Cytology: A Systematic Review and Meta-analysis of the Literature.

Urology 2016 Oct 2;96:35-43. Epub 2016 May 2.

Division of Urology, Washington University School of Medicine, Saint Louis, MO.

The diagnosis of upper tract urothelial carcinoma (UTUC) can be a challenging diagnostic pursuit. To date, there is no large-scale study assessing the statistical utility (eg, sensitivity and specificity) of selective cytology. Herein, we systematically reviewed and meta-analyzed the published literature to evaluate the efficacy of selective cytology for the detection of UTUC in patients with a suspicious clinical profile Selective cytology confers a high specificity but marginal sensitivity for the detection of UTUC. The sensitivity is greater for high-grade UTUC lesions. The statistical assessment of its utility is limited by the heterogeneity and bias of previous studies.
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http://dx.doi.org/10.1016/j.urology.2016.04.030DOI Listing
October 2016

Patient comorbidity predicts hospital length of stay after robot-assisted prostatectomy.

J Robot Surg 2016 Jun 15;10(2):151-6. Epub 2016 Apr 15.

Division of Urology, Washington University School of Medicine, Campus Box 8242, 660 S Euclid Ave, St. Louis, MO, 63110, USA.

We sought to examine the impact of baseline patient characteristics and perioperative outcomes on postoperative hospital length of stay (LOS), following the robot-assisted radical prostatectomy (RARP). We retrospectively reviewed consecutive patients receiving RARP at our institution by two surgeons between January 2012 and March 2014 (n = 274). Baseline patient characteristics were collected, including Charlson comorbidity index (CCI). Discharge criteria were identical for all patients and included: return of bowel function, pain controlled with oral medications, and ambulation without assistance. LOS was calculated as the number of midnights spent in the hospital following surgery. Postoperative hospital LOS was equal to 1 day for 225 patients and >1 day for 49 patients. Baseline patient and tumor characteristics, including age, race, body-mass index (BMI), pathologic stage, and Gleason score, were not significantly different. Mean operative time was shorter for patients with LOS > 1 day (155 vs. 173 min, p < 0.01) on univariate analysis. Patients with LOS > 1 day were more likely to have had a complication: 8/49 (17 %) vs. 14/225 (6 %), p < 0.01. However, multivariate logistic regression found baseline CCI > 2 as the only independent predictor of LOS > 1 day (OR = 3.2, p = 0.03), controlling for age, race, BMI, Gleason score, tumor stage, blood loss, operative time, and occurrence of complication. In our experience, baseline patient comorbidity, quantified by CCI, was the only independent predictor of hospital LOS greater than 1 day following RARP. Preoperative assessment of patient comorbidity should be used to better counsel patients on their anticipated postoperative course.
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http://dx.doi.org/10.1007/s11701-016-0588-6DOI Listing
June 2016

The role of the assistant during robot-assisted partial nephrectomy: does experience matter?

J Robot Surg 2016 Jun 2;10(2):129-34. Epub 2016 Apr 2.

Urology Academic Practice, Cedars-Sinai Medical Center, Los Angeles, CA, USA.

The objective of this study was to evaluate surgical outcomes with respect to the experience level of the bedside assistant during robot-assisted partial nephrectomy. A retrospective review was conducted of a prospectively maintained database of 414 consecutive robot-assisted laparoscopic partial nephrectomies performed by experienced robotic surgeons at our institution from April 2011 to September 2014. A senior-level assistant was defined as a resident in his or her post-graduate year (PGY) 4 or 5, or a fellow. Junior-level assistants were considered to be PGY-2, PGY-3, or a nurse first assistant. Multivariate analyses were performed using linear, Poisson, and logistic regression models. There were 115 junior-level cases and 299 senior-level cases. On univariate analysis, the experience level of the assistant had no impact on operative time (168 for junior level vs. 163 min for senior level, p = 0.656). Likewise, there were no differences between the junior- and senior-level groups with regard to warm ischemia time (21.3 vs. 20.9 min, p = 0.843), negative margin status (111/115 (96.5 %) vs. 280/299 (93.6 %), p = 0.340), or postoperative complications (17/115 (14.8 %) vs. 35/299 (11.7 %), p = 0.408). After multivariate analysis, operative time was associated with increased body mass index and tumor size (both p < 0.001), but not with resident experience level (p = 0.051). Estimated blood loss and postoperative complications were also not associated with the PGY of the assistant (p = 0.488 and p = 0.916, respectively). Despite common concern, the PGY status of a physician trainee serving as the bedside assistant does not appear to influence the outcomes of robot-assisted partial nephrectomy at a high-volume center.
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http://dx.doi.org/10.1007/s11701-016-0582-zDOI Listing
June 2016

Tumor diameter accurately predicts perioperative outcomes in T1 renal cancer treated with robot-assisted partial nephrectomy.

World J Urol 2016 Dec 21;34(12):1643-1650. Epub 2016 Mar 21.

Division of Urologic Surgery, Washington University School of Medicine, 4960 Children's Place, Campus Box 8242, St. Louis, MO, 63110, USA.

Purpose: To compare diameter as a continuous variable with categorical R.E.N.A.L. nephrometry score (RNS) in predicting surgical outcomes of robotic partial nephrectomy (RPN).

Methods: We retrospectively reviewed consecutive patients receiving RPN at our institution between July 2007 and June 2014 (n = 286). Three separate multivariate analyses were performed to assess the relationship between RNS components (R = radius, E = endophyticity, N = nearness to collecting system, L = location relative to polar lines), total RNS, and diameter as a continuous variable with operating time, warm ischemia time (WIT), and estimated blood loss (EBL). Each linear regression model's quality of fit to the data was assessed with coefficients of determination (R ).

Results: Continuous tumor diameter and total RNS were each significantly correlated to operative time, EBL, and WIT (p < 0.001). Categorical R related to operative time (R = 2 vs. R = 1, p = 0.001; R = 3 vs. R = 1, p = 0.001) and WIT (R = 2 vs. R = 1, p = 0.003; R = 3 vs. R = 1, p = 0.016), but not to EBL. For each of these outcomes, diameter outperformed both R and total RNS, as assessed by R . Age, body mass index, Charlson Comorbidity Index, and anterior versus posterior location did not correlate with surgical outcomes.

Conclusions: In this series of RPN from a high-volume center, surgical outcomes more closely related to tumor diameter than RNS. While RNS provides surgeons a standardized tool for preoperative planning of renal masses, tumor size may be employed as a more familiar measurement when counseling patients on potential outcomes.
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http://dx.doi.org/10.1007/s00345-016-1809-3DOI Listing
December 2016

Fibrinogen Release and Deposition on Urinary Catheters Placed during Urological Procedures.

J Urol 2016 Aug 28;196(2):416-421. Epub 2016 Jan 28.

Division of Urologic Surgery, Washington University School of Medicine, Saint Louis, MO 63110-1093, USA.

Purpose: Catheter associated urinary tract infections account for approximately 40% of all hospital acquired infections worldwide with more than 1 million cases diagnosed annually. Recent data from a catheter associated urinary tract infection animal model has shown that inflammation induced by catheterization releases host fibrinogen, which accumulates on the catheter. Further, Enterococcus faecalis catheter colonization was found to depend on EbpA (endocarditis and biofilm-associated pilus), a fibrinogen binding adhesin. We evaluated this mechanism in a human model.

Materials And Methods: Urinary catheters were collected from patients hospitalized for surgical or nonsurgical urological procedures. Catheters were subjected to immunofluorescence analyses by incubation with antifibrinogen antibody and then staining for fluorescence. Fluorescence intensity was compared to that of standard catheters. Catheters were incubated with strains of Enterococcus faecalis, Staphylococcus aureus or Candida to assess binding of those strains to fibrinogen laden catheters.

Results: After various surgical and urological procedures, 50 catheters were collected. In vivo dwell time ranged from 1 hour to 59 days. All catheters had fibrinogen deposition. Accumulation depended on dwell time but not on surgical procedure or catheter material. Catheters were probed ex vivo with E. faecalis, S. aureus and Candida albicans, which bound to catheters only in regions where fibrinogen was deposited.

Conclusions: Taken together, these data show that urinary catheters act as a binding surface for the accumulation of fibrinogen. Fibrinogen is released due to inflammation resulting from a urological procedure or catheter placement, creating a niche that can be exploited by uropathogens to cause catheter associated urinary tract infections.
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http://dx.doi.org/10.1016/j.juro.2016.01.100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4965327PMC
August 2016