Rigid and Flexible Nephroscopy

22
Rigid and Flexible Nephroscopy

Timothy Y. Tran¹ & Mantu Gupta²

¹ Providence VA Medical Center, Brown University, Providence, RI, USA

² Icahn School of Medicine at Mount Sinai, New York, NY, USA

Introduction

The first reported nephroscopy was performed when Rupel and Brown inserted a rigid cystoscope through a nephrostomy tract to remove stones during open renal surgery in 1941. Fifteen years later, Goodwin obtained the first percutaneous renal access when contrast was injected into the collecting system while attempting to perform a renal arteriogram.

Since that time, the techniques and technology associated with the percutaneous route for intrarenal surgery has grown tremendously [1]. Percutaneous nephrolithotomy (PCNL), first described in the 1980s [2], is now the gold standard for the removal of staghorn renal calculi due to its minimally invasive nature and high stone‐free rates [3]. With advances in instrumentation, use of percutaneous access has also expanded to treating renal diseases such as symptomatic renal cysts, stenotic infundibula, excluded calyces, and upper tract transitional cell carcinoma.

Rigid nephroscopes, with their offset lens and straight working channels permitting rigid instrumention, are the most commonly used instruments to clear stones from the collecting system during PCNL because of their durability and efficiency; however, there are times when, due to anatomic constraints, this instrument cannot perform all of the functions needed to render a patient stone free.

This chapter discusses recent advances in rigid nephroscopy and flexible nephroscopy through percutaneous access and covers equipment and techniques that can maximize efficiency and minimize morbidity for various percutaneous renal procedures.

Indications for nephroscopy

Diagnostic indications

With advances in endoscope technology, scope design (including digital imaging), and the use of access sheaths, the diagnostic accuracy of retrograde ureterorenoscopy for upper tract urothelial carcinoma is now 76–98%. Rigid and flexible nephroscopy as purely diagnostic procedures are therefore not routinely performed [4–6]. However, in certain patient populations, for example patients who have had cystectomy and urinary diversion who no longer have readily obtainable reterograde access, the percutaneous route may be the only option for access to the pelvicalyceal system.

Therapeutic indications

With the combination of rigid and flexible nephroscopy techniques, percutaneous nephroscopy can be used to treat the following:

Stone disease: treatment of large or complex/staghorn calculi.
Obstructed calyces, infundibular stenosis, and calyceal diverticula: access obtained in a “direct” manner in which the percutaneous access is directed at the obstructed area or an “indirect” approach where the obstructed area is accessed via another puncture site.
Ureteropelvic junction (UPJ) obstruction: antegrade endopyelotomy and/or endopyeloplasty with a balloon cutting device, holmium:YAG laser incision, hook knife, Sachse urethrotome, or endoscopic shears [7].
Upper tract transitional cell carcinoma (TCC): ablation of tumors with lasers or resection with a cautery system.

This chapter focuses on rigid and flexible nephroscopy for stone disease. Chapters 28, 30, and 31 provide further detail on using antegrade access for calyceal diverticulae, UPJ obstruction, and upper tract TCC, respectively.

Indications for flexible nephroscopy

The chief indication for flexible nephroscopy is access to calyces with stones or tumors that cannot be reached with the rigid nephroscope.

Achieving stone‐free status with a single procedure is an important consideration for both the patient and the provider. From a patient perspective, a second procedure can be very costly in terms of time away from work or quality of life. For the urologist, performing a secondary procedure during the 90‐day global period can be unappealing. It is common, however, for a surgeon to encounter a case where a patient cannot be rendered stone free using a single access and a rigid nephroscope. As such, the flexible nephroscopy is an important adjunct to rigid nephroscopy for complete stone clearance.

Flexible nephroscopy has been growing in popularity recently as surgeons have shown its use can avoid the need for an additional access. Williams and Leveillee showed that a combination of flexible and rigid nephroscopy can be successfully used to render patients stone free, even in the face of complex stone disease [8].

Flexible nephroscopy can also be used through a percutaneous access to treat obstructed calyces or a calyceal diverticulum when a rigid nephroscope cannot reach the infundibulum due to its acute angle or tightness (Figure 22.1) [9]. This indirect approach to an obstructed calyx or calyceal diverticulum is becoming more commonly utilized as opposed to a direct approach, wherein the obstructed calyx itself is percutaneously punctured, a tract established, and the stenosis treated directly. The advantage of the indirect approach is that it obviates the need for a separate nephrostomy tract with its attendant morbidity.

Image described by caption. — **Figure 22.1** A stenotic infundibulum.

Occasionally, a conventional flexible cystoscope may be too large or too cumbersome to be maneuvered into a calyx. In such instances, use of a flexible ureteroscope to access difficult‐to‐reach calyces increases the chances of rendering a patient stone free. These are generally 7 or 8 Fr and tend to have better deflection than the flexible cystoscope. Problems are encountered with fiber‐optic flexible ureteroscopes because their long length renders them not ergonomically suited for use in the kidney, their relatively flimsy nature makes them torque unstable, and their slender profile and tight distal radius of deflection make them difficult to maneuver in hydronephrotic collecting systems. Use of antegrade ureteroscopy with a flexible ureterosocpe can prove valuable for stone fragments that are located in the distal ureter, since this area usually cannot be directly accessed with a flexible cystoscope because of its distance from the percutaneous site and because of the diameter of the ureter.

The need for flexible nephroscopy during PCNL depends largely on the location of the stone and of the access. Most urologists prefer to obtain access below the 12th rib in order to reduce the risk of pleural injury. In those cases, the rigid nephroscope is usually introduced into the lower pole. The renal pelvis can usually be reached with this access, but reaching upper and mid pole calyces without placing substantial torque on the renal parenchyma is difficult, especially in obese patients or in patients with low‐lying kidneys due to hindrance from the iliac crest. It can also be challenging to reach other lower pole calyces from this position and almost impossible to evaluate the proximal ureter with a rigid nephroscope (Figure 22.2). Alternatively, if access is into the upper pole, it can also be difficult to reach the lower pole calyces, especially in patients with narrow intercostal spaces or nonmobile (fixed) kidneys.

Recent advances in scope technology

Since this volume’s last edition, the armamentarium of digital flexible ureteroscopes has expanded. Although the Invisio digital DUR‐D flexible ureteroscope (ACMI, Southborough, MA, USA) is no longer available, the Flex‐X^c (Karl Storz, Tuttlingen, Germany) and the URF‐V (Olympus, Tokyo, Japan) are commonly used. Each scope offers a reasonably narrow tip (8.5 Fr) and 270° deflection in both directions. Additionally, the URF‐V offers narrow band imaging and the Flex‐X^c offers Storz professional image enhancement system (SPIES)™ technology (Karl Storz, Tuttlingen, Germany), which can improve detection of upper tract urothelial tumors [10]. Richard Wolf (Vernon Hills, IL, USA) offers the Boa Vision and Cobra Vision digital ureteroscopes, which have similar functionality as the URF‐V and Flex‐X^c.

Recently, the LithoVue™ flexible ureteroscope (Boston Scientific, Marlborough, MA, USA) has been introduced as a new‐generation single‐use instrument. Dragos et al. demonstrated similar performance in terms of maneuverability, angle deflection, and ability to access calyces during retrograde renoscopy [11]. As an alternative to reusable ureteroscopes, its proposed advantages include high‐quality images with each use (as there would be no damage to a new scope) and financial savings on servicing and cleaning costs. Overall, the improved torque stability of digital ureteroscopes in comparison to fiber‐optic ureteroscopes allows for improved manuerverability through tight infundibula or hydronephrotic systems.

Similarly, improvements in image‐processing technology have yielded benefits for the endoscopic surgeon. The SPIES™ provides a high‐definition image with real‐time image enhancements useful for nephroscopy [12]. The SPIES CLARA™ feature automatically brightens darkened areas, which eliminates the need for either increasing the light intensity or bringing the scope closer to a darker area. These improvements eliminate the need for maneuvers that may cause glare or result in loss of perspective of the surgical field.

Digital cystoscopes offer similar improvements in visualization compared with their fiber‐optic counterparts. However, in contradistinction to digital ureteroscopes, the increased rigidity and girth of these scopes and their more limited deflection can limit their maneuverability and their ability to reach all calyces within the collecting system. As such, oftentimes a fiber‐optic cystoscope can be of greater utility for flexible nephroscopy.

Since the publication of the last edition, few changes in rigid nephroscopy and in technology for rigid nephroscopes for standard PCNL have been described. Innovations in scopes for smaller caliber PCNL (i.e. mini‐, ultra‐mini, and micro‐PCNL) are described in Chapter 24.