New ex-vivo organ model for percutaneous renal surgery

OBJECTIVES: Percutaneous Renal Surgery (PRS) is a demanding procedure and success is mostly hampered by the lacking of training facilities. Thus, the purpose of the study was to evaluate a significantly improved pre-existing porcine kidney-training model for percutaneous renal access and PRS. MATERIALS AND METHODS: A biologic training model using porcine kidneys coated by a full-thickness porcine skin flap was prepared. The ureter was dissected, stones were placed into the collecting system using an 18F amplatz sheath, and a catheter was placed in the ureter for further irrigation with saline or contrast medium. For initial training with an easy access, a standard guide-wire was inserted in the ureter through the renal parenchyma. The kidney was punctured with radiographic or ultrasound guidance. Minimally invasive percutaneous nephrolithotomy (MIP) was then tested using the model under radiographic or ultrasound guidance. The model was then evaluated in MIP training courses, which are regularly held at The Hannover Medical School. RESULTS: All trainees were urologists with experience in endourologic surgery but lacked practice in PRS. In conclusion, all 36 participants attained access to the collecting system using models with readily placed guide-wires. Subsequently, PRS was successful in all cases. Percutaneous puncture under ultrasound guidance and following intrarenal surgery was successful in 30 (83.3 percent) cases. Therefore, all participants rated the model useful for simulating percutaneous renal surgery. CONCLUSIONS: This new porcine kidney model is easy to build and is made cost effective by using readily available material. Moreover, it provides realistic and reproducible training model for PRS. The "organ" model mimics the retroperitoneum by having a full-thickness skin flap with a layer of subcutaneous fatty tissue.

Steerable antegrade stenting: a new trick of the trade

INTRODUCTION: Whereas a retrograde attempt to insert an indwelling stent is performed in lithotomy position, usually renal access is gained in a prone position. To overcome the time loss of patient repositioning, a renal puncture can be performed in a modified lithotomy position with torqued truncus and slightly elevated flank. There is a two-fold advantage of this position: transurethral and transrenal access can be obtained using a combined approach. In the present study, this simple technique is used to position a floppy guide wire through a modified needle directly through the renal pelvis into the ureter. MATERIALS AND METHODS: The kidney is punctured in the modified lithotomy position under sonographic control using an initial three-part puncture needle. A floppy tip guide-wire is inserted into the collecting system via the needle after retrieving the stylet. The retracted needle is bent at the tip while the guide-wire is secured in the needle and the collecting system. The use of the floppy tip guide-wire helps to insert the curved needle back into the kidney pelvis, which becomes the precise guidance for the now steerable wire. The desired steerable stent is positioned under radiographic control in a retrograde fashion over the endoscopically harbored tip of the guide-wire. Two patient cohorts (newly described method and conventional method) were compared. RESULTS: The presented steering procedure saves 16.5 mean minutes compared to the conventional antegrade stenting and 79.5 Euros compared to the control group. CONCLUSION: The described combined antegrade-retrograde stent placement through a bent three-part puncture needle results in both clinical superiority (OR time, success rate) and financial benefits.