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.

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.

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.

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.