Initial experience: ex-vivo perfused pig kidney to study urinary oxalate excretion.

Existing animal models of renal oxalate excretion utilize either gut or peritoneal cavity for oxalate absorption. Ex vivo renal perfusion is an established tool for graft preservation. We sought to repurpose this concept to study the early pathogenesis of urinary lithiasis. Juvenile female Yorkshire porcine kidneys were removed laparoscopically and placed on an ex vivo cardiopulmonary bypass circuit utilizing whole-blood based perfusate. Pre-defined goals were identified for each attempt (n = 5) with plans to increase physiologic model complexity. Tissue perfusion and oxygenation were monitored by serial perfusate iSTAT testing. Once steady urine production was achieved, aqueous oxalate was injected into the perfusate. Renal outcomes were assessed by histology and blood/urinary assays. After demonstrating proof-of-concept in early trials, normothermic (37 °C) ex vivo whole-blood perfusion with Steen Solution™ was performed exceeding three hours at physiologic mean arterial pressures. Circuit parameters remained in the physiologic range for electrolytes, temperature, mean arterial pressure, lactate, and pH. Urine was produced in three experiments. Urinary filtrate demonstrated consistently higher urine creatinine compared to perfusate, and arterial perfusate oxalate boluses lead to urinary oxalate spikes followed by continuous oxalate clearance. Histopathologic analysis with H&E and Pizzolato's method staining demonstrated formation of calcium oxalate crystals. In light of these promising metabolite clearances, ex vivo porcine renal perfusion appears to be a feasible alternative to study oxalate excretion. Longer validation studies are necessary to establish this technique as a model for kidney stone pathogenesis.

Perioperative Aspirin Use Is Associated with Bleeding Complications during Robotic Partial Nephrectomy.

PURPOSE: Daily aspirin use following cardiovascular intervention is commonplace and creates concern regarding bleeding risk in patients undergoing surgery. Despite its cardio-protective role, aspirin is often discontinued 5-7 days prior to major surgery due to bleeding concerns. Single institution studies have investigated perioperative outcomes of aspirin use in robotic partial nephrectomy (RPN). We sought to evaluate the outcomes of perioperative aspirin (pASA) use during RPN in a multicenter setting. MATERIALS AND METHODS: We performed a retrospective evaluation of patients undergoing RPN at 5 high volume RPN institutions. We compared perioperative outcomes of patients taking pASA (81 mg) to those not on aspirin. We analyzed the association between pASA use and perioperative transfusion. RESULTS: Of 1,565 patients undergoing RPN, 228 (14.5%) patients continued pASA and were older (62.8 vs 56.8 years, p <0.001) with higher Charlson scores (mean 3 vs 2, p <0.001). pASA was associated with increased perioperative blood transfusions (11% vs 4%, p <0.001) and major complications (10% vs 3%, p <0.001). On multivariable analysis, pASA was associated with increased transfusion risk (OR 1.94, 1.10-3.45, 95% CI). CONCLUSIONS: In experienced hands, perioperative aspirin 81 mg use during RPN is reasonable and safe; however, there is a higher risk of blood transfusions and major complications. Future studies are needed to clarify the role of antiplatelet therapy in RPN patients requiring pASA for primary or secondary prevention of cardiovascular events.

Validation of aorta-lesion-attenuation difference on preoperative contrast-enhanced computed tomography scan to differentiate between malignant and benign oncocytic renal tumors.

OBJECTIVES: We previously noted that the aorta-lesion-attenuation difference (ALAD) determined on CT scan discriminated well between chromophobe RCC and oncocytoma. The current evaluation seeks to validate these initial findings in a second cohort of nephrectomy patients. METHODS: A retrospective review of preoperative CT scans and surgical pathology was performed on patients undergoing nephrectomy for small, solid renal masses. ALAD was calculated by measuring the difference in Hounsfield units (HU) between the aorta and the lesion of interest on the same image slice on preoperative CT scan. The discriminative ability of ALAD to differentiate malignant pathology from oncocytoma was evaluated by sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under curve (AUC) using ROC analysis. RESULTS: Twenty-one preoperative CT scans and corresponding pathology reports were reviewed and included in the validation cohort. ALAD values were calculated during the excretory and nephrographic phases. Compared to the training cohort, patients in the validation cohort were significantly older (62 versus 59 years old), had larger tumors (3.7 versus 2.7 cm), and higher stage disease (59% versus 79% T1a disease). Nephrographic ALAD was able to differentiate malignant pathology from oncocytoma in the training and validation cohorts with a sensitivity of 84% versus 73%, specificity of 86% and 67%, PPV of 98% versus 91%, and NPV of 33% versus 35%. The AUC for malignant pathology versus oncocytoma in the validation cohort was 0.72 (95% CI 0.63-0.82). Nephrographic ALAD was able to differentiate chromophobe RCC from oncocytoma in the training and validation cohorts with a sensitivity of 100% versus 67%, specificity of 86% versus 67%, PPV of 75% versus 43%, and NPV of 100% versus 84%. The AUC for chromophobe RCC versus oncocytoma in the validation cohort was 0.72 (95% CI 0.48-0.96). CONCLUSIONS: The ability of ALAD to discriminate between chromophobe RCC and oncocytoma was diminished in the validation cohort compared to the training cohort, but remained significant. The current findings support further investigation in the role of ALAD in the management of patients with indeterminate diagnoses of oncocytic neoplasm.

Percutaneous Removal of Retained Metallic Ureteral Stent with a Looped Polytetrafluoroethylene-Coated Guidewire.

Background: Ureteral stricture disease is a troubling urologic issue that can be managed with surgical reconstruction or, more conservatively, with chronic nephrostomy tubes or ureteral stents. These indwelling tubes require exchanges and are prone to complications such as encrustation or stent failure. Metallic ureteral stents are designed to be more resistant to extrinsic compression and allow for exchanges at longer intervals. However, encrustation or tissue ingrowth can occur with these stents as well. The removal of encrusted or embedded metallic ureteral stents poses a difficult clinical scenario. We present a case of an encrusted metallic stent embedded in a proximal ureteral stricture requiring percutaneous endoscopic removal with a novel looped-wire technique. Case Presentation: A 50-year-old Caucasian man with bilateral ureteral stricture disease, managed with chronic indwelling metallic stents, failed retrograde removal on the right during routine exchange. Staged procedures with percutaneous nephrostomy, followed by combined percutaneous antegrade and retrograde endoscopy were required to observe and access the embedded stent. The exposed metallic surface was unable to be grasped by available instruments through flexible endoscopy. Under endoscopic control with fluoroscopic guidance, a polytetrafluoroethylene (PTFE)-coated guidewire was looped around the metallic stent. With gentle traction on the wire loop, the embedded stent curl was delivered out of the stricture and into the renal pelvis from where it was extracted carefully with graspers inserted through a rigid nephroscope. Follow-up antegrade fluoroscopic studies with contrast showed no extravasation. Conclusion: Percutaneous removal of metallic stents retained within the ureter has unique challenges. We present a novel method of extraction of a retained metallic stent with a looped PTFE-coated guidewire, which may safely and effectively be used in complex situations.

Endoscopic Management of Chyluria Caused by Pyelolymphatic Fistula After Robot-Assisted Laparoscopic Pyeloplasty.

Background: Chyluria is a rare diagnosis classically associated with milky-appearing urine. It involves the leakage of chyle into the urinary tract. Although the most common cause of chyluria worldwide is infectious in nature, other noninfectious etiologies have been described. Classically chyluria resolves spontaneously or with conservative management. Surgical treatments have been described but are not often required. We present a case of iatrogenic pyelolymphatic fistula after robot-assisted laparoscopic dismembered pyeloplasty that was treated with endoscopic electrocautery of the fistulous tract. Case Presentation: A 50-year-old Caucasian man underwent a robot-assisted laparoscopic dismembered pyeloplasty with stent insertion for radiographically demonstrated left ureteropelvic junction obstruction. His postoperative course was uneventful until 4-week follow-up at which time he began to notice intermittent passage of milky-appearing urine. Urinalysis was notable for large protein and elevated urine triglycerides. He was initially managed conservatively dietary modifications without success. He then underwent endoscopic management with cystoscopy and ureteroscopy with fulguration of suspected pyelolymphatic fistula. He was maintained on a low-fat medium-chain triglyceride diet and octreotide injections while inpatient for 1 week postoperatively. His postoperative course was unremarkable and no return of chyluria was observed. His chyluria remained resolved at 9 months postoperatively. Conclusion: Pyelolymphatic fistula after robot-assisted laparoscopic pyeloplasty is a theoretical complication of perirenal dissection and has not been previously described in the literature. It should be considered as a rare iatrogenic cause of chyluria. Endoscopic management with fulguration is technically feasible and may obviate the need for more invasive surgical management.

Patient Perceptions of Chaperones during Intimate Examinations and Procedures in Urology Clinic.

INTRODUCTION: We surveyed patients on their expectations and preferences regarding chaperones during intimate examinations and procedures in urology clinic. METHODS: Patients identified in the outpatient urology clinic were queried for demographics, expectations and preferences regarding chaperones through a 16-item survey. RESULTS: We collected data from 200 patients (52.5% male, 47.5% female), average age 60.5 years (SD ± 15.5). Most patients were Caucasian (84.5%), completed some college (65.5%) and were married (52.0%). Most had a prior genitourinary procedure (men 74.7%, women 62.4%), during which 21.5% of men vs 60.7% of women had chaperones present. Most patients did not care if they had a chaperone (men 53.3%, women 54.7%). Only 11.5% of patients preferred a chaperone. Of that minority there was a higher percentage of women who preferred a chaperone compared to men (men 3.8%, women 20%). The majority of patients did not care about the gender of the chaperone but cited comfort level with the provider (men 50.0%, women 54.9%) and invasiveness of procedure or examination (men 36.4%, women 35.4%) as most important. The majority of patients (men 84.8%, women 88.4%) felt that they should have the right to refuse a chaperone. CONCLUSIONS: A minority of patients preferred to have a chaperone during an intimate examination or procedure in urology clinic. Patients prioritized comfort level with the provider, which trumped gender of provider, invasiveness of examination and identity of the chaperone. The use of chaperones during intimate examinations and procedures is routine at many institutions. In an era of patient centered care it is crucial to understand patient preferences and expectations.

Using Aorta-Lesion-Attenuation Difference on Preoperative Contrast-enhanced Computed Tomography Scan to Differentiate Between Malignant and Benign Renal Tumors.

OBJECTIVE: To evaluate the ability of Aorta-Lesion-Attenuation Difference (ALAD) to differentiate malignant renal tumors from renal oncocytomas. METHODS: A retrospective review of preoperative computed tomography (CT) scans and surgical pathology was performed on patients undergoing partial nephrectomy for small, solid renal masses. ALAD was calculated by measuring the difference in Hounsfield units (HU) between the aorta and the lesion of interest on the same image slice on preoperative CT scan. The discriminative ability of ALAD to differentiate malignant pathology from oncocytoma was evaluated by sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under curve (AUC) using receiver operating characteristic analysis. RESULTS: A total of 227 preoperative CT scans and corresponding pathology reports were reviewed. ALAD values were calculated during the excretory and nephrographic phases. Nephrographic ALAD was able to differentiate malignant pathology from oncocytoma using a HU threshold of 24 with a sensitivity of 84%, specificity of 86%, PPV of 98%, and NPV of 33%. The AUC for malignant pathology vs oncocytoma was 0.86 (95% confidence intervals 0.77-0.96). Nephrographic ALAD was able to differentiate chromophobe renal cell carcinoma (RCC) from oncocytoma using a HU threshold of 24 with a sensitivity of 100%, specificity of 86%, PPV of 75%, and NPV of 100%. The AUC for chromophobe RCC vs oncocytoma was 0.98 (95% confidence intervals 0.91-1.00). CONCLUSION: ALAD discriminates well between chromophobe RCC and oncocytoma, which may aid in the management of patients with indeterminate diagnoses of oncocytic neoplasm on diagnostic needle biopsy. Further validation of ALAD will be necessary prior to routine use in clinical practice.

Penile sparing surgical approaches for primary penile tumors: preserving function and appearance.

Penile cancer is a rare and potentially disfiguring disease. There are multiple treatment options for primary penile lesions. Penile sparing approaches offer an attractive option as they can provide several quality of life benefits without detrimental oncologic outcomes. With appropriate diagnostic evaluation and staging, penile sparing techniques provide proper cancer control with improved cosmetic and functional results. Regardless of the chosen treatment modality, a commitment to close follow-up remains a critical component of all treatment considerations. The goal of this review is to provide an overview of the multiple treatment strategies for primary penile tumors with a focus on penile sparing surgical approaches.

Penile artery shunt syndrome: a novel cause of erectile dysfunction after penile revascularization surgery.

INTRODUCTION: Penile revascularization is a surgical treatment option for erectile dysfunction (ED) in healthy individuals due to a focal arterial occlusion in the absence of generalized vascular disease. Most described failures have been attributed to graft stenosis or disruption of the anastomosis. AIM: We report a novel phenomenon called Penile Artery Shunt Syndrome that contributed to persistent ED in a patient after penile microvascular arterial bypass surgery. METHODS: A 26-year-old man presented for evaluation of long-standing ED, which was attributed to trauma sustained 12 years earlier. He had difficulty obtaining and maintaining erections despite oral pharmacotherapy. Clinical data related to the case were studied, analyzed, and reviewed with urologic and radiologic specialists at multiple centers that collaborated in the care of this patient. MAIN OUTCOME MEASURES: Penile duplex ultrasound peak systolic velocities and five-item International Index for Erectile Function questionnaire scores were the main outcome measures. RESULTS: Initial diagnostic workup of the patient confirmed severe insufficiency of the left cavernosal artery, with no evidence of venous leak. The patient underwent penile microvascular arterial bypass surgery with anastomosis of the left inferior epigastric artery to the left dorsal penile artery. The patient had persistence of severe ED despite patent anastomosis by penile duplex ultrasound. Subsequent arteriography revealed an arterial shunt due to an aberrant obturator artery arising from the donor inferior epigastric artery. The patient underwent embolization of the aberrant obturator artery, with resolution of the shunt and marked improvement in erectile function. CONCLUSIONS: The presence of an aberrant obturator artery arising from the inferior epigastric artery may predispose to persistent ED after revascularization due to the creation of a shunt phenomenon. Pelvic arteriography may be useful in identifying anomalous anatomic considerations prior to penile revascularization and to evaluate patients with persistent postoperative ED.