Pathologic evaluation of hemostatic agents in percutaneous nephrolithotomy tracts in a porcine model.

BACKGROUND AND PURPOSE: Hemostatic agents have been suggested as an adjunct for tubeless percutaneous nephrolithotomy (PCNL). We pathologically evaluated the percutaneous tracts injected with the fibrin sealant (FS) Evicel and hemostatic gelatin matrix (HGM) Surgiflo at various time intervals to determine their absorption and tract closure rates. We also evaluated whether these agents reduced urine leak rates in a porcine model. MATERIALS AND METHODS: Percutaneous access was obtained in 19 kidneys in 10 domestic swine. The tracts were dilated to 30F using a balloon dilating catheter. Ten kidneys served as controls. Surgiflo was injected into the tract of four kidneys, and Evicel was injected into the tract of five kidneys. Intravenous urography (IVU) was performed on postoperative days (POD) 1 and 10 to 14. IVU was performed on two pigs at POD 30. The pigs were sacrificed and kidneys were harvested for pathologic evaluation. RESULTS: Two (20%) control kidneys had a urine leak on IVU on POD 1. None of the kidneys treated with HGM or FS had a urine leak on POD 1. None of the kidneys had a leak on POD 10 to 14 or POD 30. On pathologic inspection, the tracts of all the control kidneys and HGM kidneys had closed completely at POD 14. Two kidneys treated with FS had fistula at POD 6 and POD 14. At POD 30, the tracts in the control kidneys and kidney treated with HGM had completely healed. Fibrin sealant remained in the tract at POD 30. CONCLUSION: Fibrin sealant should be used with caution because it can persist in the tract for up to 30 days and may inhibit wound healing. Hemostatic gelatin matrix is the preferable agent because the tract closed by POD 10 to 14, similar to the findings in the control animals. The use of hemostatic agents in a nephroscopy tract may reduce the risk of early urine leak after tubeless PCNL.

The digital flexible ureteroscope: in vitro assessment of optical characteristics.

INTRODUCTION: Recent advances in endoscope design have placed the charged coupled device chip on the tip of the endoscope. The image is instantly digitalized and converted into an electrical signal for transmission. Digital technology was first introduced into flexible cystoscopes/nephroscopes and subsequently into rigid and flexible ureteroscopes. Herein, we assess the image characteristics and advantages of a new generation of digital flexible ureteroscopes. METHODS: The Olympus URF-V flexible digital ureteroscope and the Olympus URF-P3 fiberoptic ureteroscope were assessed in vitro for image resolution, distortion, color representation, grayscale imaging, field of view, and depth of field. RESULTS: The digital ureteroscope had a higher resolution at 3, 5, 10, and 20 mm (25.2 lines/mm vs. 8.0, 14.1 vs. 5.0, 6.3 vs. 2.8, and 3.2 vs. 1.3), respectively. Distortion with the digital flexible ureteroscope was lower, though not statistically significant. Color representation was better with the digital ureteroscope, whereas contrast evaluation was comparable between both scopes. The digital flexlible ureteroscope produced a 5.3 times larger image size compared with the standard fiberoptic flexible uretersocpe with a narrower field of view. The depth of field was limited by light and not the optic or the camera for both ureteroscopes. CONCLUSIONS: The development of digital flexible ureteroscopes represents a significant technological advance in urology. These devices offer significantly improved resolution and color reproduction as compared with traditional fiberoptic flexible ureteroscopes. Future clinical trials are warranted to ultimately determine the advantages of these innovative endoscopes.

Reduced radiation exposure with the use of an air retrograde pyelogram during fluoroscopic access for percutaneous nephrolithotomy.

INTRODUCTION: Fluoroscopy with retrograde pyelogram is commonly used to obtain access for percutaneous nephrolithotomy (PNL). Our practice uses room air for retrograde identification of calyceal anatomy. Herein we explore whether an air pyelogram was associated with a decrease in radiation exposure compared with standard retrograde pyelogram. METHODS: We retrospectively reviewed all PNL procedures performed at our institution over the past 2 years. Of the 260 PNL procedures performed during the study period, 96 had information on radiation dosage required for analysis. The effective dose (ED) was calculated using accepted conversion tables. Multivariable linear regression was used to determine the association between ED and the use of air pyelogram controlling for factors thought to affect radiation exposure. RESULTS: Of the 96 PNL procedures included in the study, 60 (63%) were performed with an air retrograde pyelogram (AP) and 36 (37%) used contrast retrograde pyelogram (CP). Both groups were matched in terms of age, body mass index, stone burden, and number of access tracts. Multivariable linear regression showed significantly lower radiation exposure in the AP group than in the CP group (p = 0.001). There was no difference in fluoroscopy time between the two groups. Using an AP lowered the mean adjusted ED nearly twofold, from 7.67 (CI = 5.99-9.81) to 4.45 (CI = 3.68-5.38) mSv. CONCLUSIONS: An air retrograde pyelogram is associated with decreased radiation exposure during PNL when compared with a contrast retrograde pyelogram.