DUR-8 Elite has a second active deflection located more proximally on the shaft, allowing a maximum deflection of > 270° as well as an S-shaped deflection. Recently, two new-generation flexible ureteroscopes, the Flex-X (Karl Storz) and the DUR-8 Elite (ACMI) have been introduced with a crush-resistant flexible shaft, and dual 270° deflection. For this purpose unsheathed nitinol baskets (naked basket concept) were employed which allowed an additional 15− 20° of active deflection and a 2-30 fold increase in irrigant flow. This decrease in irrigant flow causes deterioration in visibility especially if debris or bleeding is present. It is important to remember that 500 µ laser fiber is not recommended to be used with flexible ureteroscope due to risk of fiber breakage and ureteroscope damage.Īmes et al., studied the impact of various available nitinol baskets on ureteroscope channel flow and deflection and found that average baseline irrigant flow (46.6 ml/min) decreases by 78.5% to 9.9ml/min with the smaller baskets (Microvasive 1.9F and Cook 2.2 F) and by 99.1% to 0.4 ml/min with larger baskets (ACMI 3F and Microvasive 3.0F). Shvarts et al., found that nitinol baskets, 200 µ and 360µ laser fiber decrease the maximal deflection angle by 4.4, 9.9 and 27.7% respectively. Another advantage of the dual deflection ureteroscope is that they allow use of larger instruments in the working port with a smaller impact on overall deflection. With a second, more proximal, unidirectional deflection point controlled with a separate lever, this ureteroscope has the ability to achieve greater overall deflection and thus may be of significant benefit in the management of LC stone disease. This limitation of ureteroscopy in the management of LC stone disease has led to the development of a dual deflection ureteroscope. reported a failure rate of 21% and 42% due to inability to access the LC effectively. In addition, even when the ureteroscope can be maneuvered into the LC and the stone is located, the placement of instruments or laser fibers in the working channel can decrease the maximal angle of deflection and prevent further access or examination of the stone burden. Intrinsic limitations of the deflection capabilities of the single-deflection ureteroscope limit their ability to execute the difficult angles necessary to gain access to many LC stones. In this review we discuss the technical development in intrarenal surgery and its application for the management of LC stones less than 10 mm in maximum dimension.ĮVOLUTION OF FLEXIBLE URETERO-RENOSCOPES AND ITS IMPLICATION IN TREATMENT OF LOWER POLE CALCULI Parallel to these developments, there is an increasing interest in application of retrograde intrarenal surgery (RIRS) for treatment of renal calculi. This is generally attributed to improvements in fiber optics designs, downsizing of instrumentations, better irrigation system and the availability of small instruments, both powered and mechanical to allow complex maneuvers within the confines of the upper urinary tract. The role of flexible ureteroscopy in the urologist's armamentarium has undergone a dramatic evolution. Hence, its results have been less than optimal for LC stones and in particular for patients with unfavorable intrarenal anatomy since these fragments are less likely to clear with SWL. Extracorporeal shock wave lithotripsy (SWL) is a technology that relies on spontaneous passage of the fragment to achieve a stone-free state. Treatment of lower pole calyceal (LC) stones presents a dilemma for the urologist.
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