A continuum of mineralization from human renal pyramid to stones on stems.

The development of new modalities for kidney stone prevention rests upon understanding the progression of mineralization within the renal pyramid. The progression from small foci of mineralized volumes within the renal pyramid to larger interstitial plaques that ultimately lead into clinically detectable calcium-based stones on calcium phosphate stems will be presented through correlative microscopy approach. High resolution X-ray computed tomography (micro-XCT), electron microscopy, and energy dispersive X-ray (EDX) compositional analyses of interstitial plaques, stems, and attached stones were performed. Increase in mineral density progressed with mineralization severity, with the highest mineral densities detected within mature Randall's plaque and stems to which kidney stones were attached. EDX analyses revealed variable elemental composition within interstitial plaque, stems, and stones. Micro-XCT reconstructions of stones with stems enabled visualization of unoccluded tubules within stems, with average tubule diameters corresponding to thin limbs of Henle, blood vessels, and collecting ducts. Correlative microscopy confirmed that the progression of mineralization leading to calcium-based nephrolithiasis occurs through a continuum involving four anatomically and structurally distinct biomineralization regions: 1) proximal intratubular mineralization within the renal pyramid; 2) interstitial Randall's plaque near the tip of the papilla; 3) emerging plaque (stems); and, 4) the body of heterogeneous stones. STATEMENT OF SIGNIFICANCE: Nephrolithiasis is a common condition affecting nearly 1 in 11 Americans. The most common type of stone, calcium oxalate is known to form on a calcium phosphate deposit on the renal papilla known as Randall's plaque. Novel imaging techniques have identified distinct regions of biomineralization not just at the tip, but throughout the renal papilla. The classic understanding of Randall's plaque formation is reformulated using correlative imaging techniques. This study establishes a stepwise progression of anatomically-specific biomineralization events including, 1) proximal intratubular mineralization within the renal pyramid; 2) interstitial Randall's plaque near the tip of the papilla; 3) emerging plaque (stems); and, 4) the body of heterogeneous stones, and provides insights into the need for plausible site-specific therapeutic intervention.

Derivation of decision rules to predict clinically important outcomes in acute flank pain patients.

OBJECTIVE: Routine CT for patients with acute flank pain has not been shown to improve patient outcomes, and it may unnecessarily expose patients to radiation and increased costs. As preliminary steps toward the development of a guideline for selective CT, we sought to determine the prevalence of clinically important outcomes in patients with acute flank pain and derive preliminary decision rules. METHODS: We analyzed data from a randomized trial of CT vs. ultrasonography for patients with acute flank pain from 15 EDs between October 2011 and February 2013. Clinically important outcomes were defined as inpatient admission for ureteral stones and alternative diagnoses. Clinically important stones were defined as stones requiring urologic intervention. We sought to derive highly sensitive decision rules for both outcomes. RESULTS: Of 2759 participants, 236 (8.6%) had a clinically important outcome and 143 (5.2%) had a clinically important stone. A CDR including anemia (hemoglobin <13.2g/dl), WBC count >11000/µl, age>42years, and the absence of CVAT had a sensitivity of 97.9% (95% CI 94.8-99.2%) and specificity of 18.7% (95% 17.2-20.2%) for clinically important outcome. A CDR including hydronephrosis, prior history of stone, and WBC count <8300/µl had a sensitivity of 98.6% (95% CI 94.5-99.7%) and specificity of 26.0% (95% 24.2-27.7%) for clinically important stone. CONCLUSIONS: We determined the prevalence of clinically important outcomes in patients with acute flank pain, and derived preliminary high sensitivity CDRs that predict them. Validation of CDRs with similar test characteristics would require prospective enrollment of 2100 patients.

T-shaped shunt and intracavernous tunneling for prolonged ischemic priapism.

PURPOSE: Conservative management of prolonged ischemic priapism is rarely effective. Interventions include corporal aspiration/irrigation, injection of vasoconstrictive agents or surgical procedures. We describe a technique that fulfills several important criteria in the surgical management of ischemic priapism in that immediate resolution of ischemic pain is achieved, a wide area, reliably patent shunt is created, the procedure is technically simple and it may be performed with the patient under a local anesthetic. MATERIALS AND METHODS: We reviewed the records of 13 patients treated with the T-shunt for whom followup, including erectile function, was available. RESULTS: Records were available for review for 13 men who underwent the T-shunt procedure from April 2006 to January 2008. In most cases priapism had lasted for more than 24 hours and previous irrigation/intracorporal administration of sympathomimetics had been unsuccessful. Of these 13 men 6 had undergone unsuccessful distal or proximal shunt procedures before presentation to our service. All procedures were performed using local anesthetic only. Cavernous blood flow was restored in all but 1 patient and another required a second procedure. T-shunts resulted in resolution of penile pain in all patients and all but 2 had recovery of erectile function. CONCLUSIONS: The T-shunt technique results in immediate resolution of ischemic penile pain and rigidity. Ultrasonography confirms that blood flow is usually restored to the previously ischemic corpora cavernosa after the procedure. The T-shaped shunt is simple and reliable, and access also allows for proximal trans-shunt dilation. We observed surprisingly excellent recovery of erectile function. This procedure may facilitate recanalization of corporal circulation and could make proximal shunts obsolete.

Failed percutaneous balloon dilation for renal access: incidence and risk factors.

OBJECTIVES: To present our experience using balloon dilation and discuss secondary techniques to establish a percutaneous tract when balloon dilation fails. Balloon dilation is a safe and effective method to achieve percutaneous renal access, but it is not uniformly successful. Also, the failure rate and risk factors have not been well documented. METHODS: We retrospectively reviewed our last 99 consecutive percutaneous renal procedures using a balloon system as our initial dilation modality. In all cases, the urologist achieved needle access. We determined the balloon failure rate, relationship to prior renal surgery and other patient-related factors, and success rate using secondary techniques of tract dilation. RESULTS: The balloon did not adequately dilate a tract in 17 (17% failure rate) of 99 cases. The risk factors for failure included a history of prior ipsilateral renal surgery (25% failure rate versus 8% without surgery) and subcostal compared with supracostal puncture (18% versus 9% failure rate). The failure rate was not increased when stratified by laterality, stone composition, stone size and location, or history of ipsilateral renal infection. Amplatz dilators were used in 16 refractory cases and were successful in 15. Metal Alken dilators were successfully used in 2 patients. CONCLUSIONS: The balloon dilation system is commonly used as the primary modality to establish percutaneous renal access. Although safe and effective (83%), the success rate drops dramatically in patients with prior ipsilateral renal surgery. Knowledge and skill with alternative dilation systems, such as Amplatz or metal Alken dilators, are necessary to successfully gain entry into all renal collecting systems.