Access to the Ureter: Rigid Ureteroscopy

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Access to the Ureter: Rigid Ureteroscopy

Jose De La Cerda, III & Timothy Y. Tseng

Department of Urology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA

Introduction

With ongoing technological advances in both minimally invasive and noninvasive techniques, there are increasing options for the evaluation and treatment of ureteral pathology. In particular, advances in the miniaturization and optics of flexible endoscopic equipment have dramatically improved the success of endoscopic treatment for proximal ureteral and renal collecting system pathology. Despite these innovations, rigid ureteroscopy demonstrates distinct advantages and retains a key role in the treatment of upper urinary tract pathology.

Indications for semirigid and rigid ureteroscopy

With larger working channels that allow for enhanced irrigation and passage of larger endoscopic instruments such as biopsy forceps, rigid and semirigid ureteroscopes are the favored approach for access to the distal ureter and treatment of all distal ureteral conditions including ureteral calculi, tumors, and strictures [1, 2]. Classically, the ureter is divided into three segments: the mid ureter overlying the sacrum, and the proximal and distal ureter superior and inferior to the sacrum [3, 4]. In practice, rigid ureteroscopy was occasionally limited by the natural angulation of the ureter over the iliac vessels [5]. Semirigid ureteroscopes, which contain fiber‐optic bundles rather than a solid lens, can overcome this limitation by affording a small degree of shaft flexion over the iliac vessels.

For distal ureteral calculi, rigid and semirigid ureteroscopy demonstrate superior stone‐free rates compared to shock‐wave lithotripsy (SWL) (90–97% vs. 75%, respectively) [2]. Rigid and semirigid ureteroscopy also appear to have stone‐free rates comparable to endoscopy with flexible ureteroscopes only (90–97% vs. 93–97%, respectively) [2]. Recent data have also demonstrated that rigid and semirigid ureteroscopy can be used to successfully treat proximal ureteral stones [6]. Although flexible ureteroscopy demonstrates the highest stone‐free rate for treating stones at any location in the ureter (95%), rigid and semirigid ureteroscopy demonstrate stone‐free rates that are only somewhat lower (85–92%) [6]. This is in contrast to SWL, which demonstrates a stone‐free rate for stones at any ureteral location of only 69% [1]. These data emphasize the fact that rigid and semirigid ureteroscopy can be used successfully throughout the ureter and that their use should not be dogmatically limited to the distal ureter. Because of their advantages and relative ease of use, rigid and semirigid ureteroscopy can be the initial modality for accessing the ureter as far proximally as the anatomy safely permits.

Preoperative considerations

As with any surgical patient, a thorough history and physical examination are key to identifying conditions that may lead to potential intraoperative and perioperative complications [7]. The American Society of Anesthesiologists recommends against the routine ordering of preoperative laboratory studies in patients without risk factors, although this remains controversial [8]. According to guidelines from the American Urological Association, a complete blood count would not be necessary for ureteroscopy as the risk of hemorrhage is very low. Serum creatinine and electrolytes are necessary if there is suspicion for decreased renal function [1]. With any planned urinary tract instrumentation, preoperative urinalysis and culture should be obtained and culture‐specific antibiotics should be prescribed to attempt to sterilize the urine prior to the procedure [1, 9]. In the absence of clinical indications, coagulation studies do not need to be routinely obtained prior to the endoscopic management of stone disease [1, 8]. Indeed, ureteroscopy with holmium:YAG lithotripsy has been shown to be safe and effective in patients on full therapeutic antiplatelet and anticoagulant therapy [10].

Although placing a ureteral stent prior to ureteroscopy to allow passive dilation of the ureter has been shown to lead to decreased operative time and higher stone‐free rates [11–13], this is not recommended as a routine practice due to the added costs and diminished quality of life associated with stenting [1].

Patient positioning

Two positions have been described for ureteroscopy: dorsal lithotomy and modified dorsal lithotomy in which the ipsilateral leg of the ureter being examined is slightly extended and abducted [14] (see Figure 44.1). Immediately after induction of anesthesia, the patient can be positioned according to surgeon preference. Extension of the leg and abduction of the hip minimizes the angle of the ureter over the psoas muscle and therefore facilitates the passage of the rigid or semirigid ureteroscope into the ureteral orifice and proximally into the ureter [15]. In a study by Korkes et al. the modified dorsal lithotomy position resulted in a significant decrease in operative time when compared to the dorsal lithotomy position [14]. Complication and success rates remained similar between both positions.

Image of the ureter being accessed with a single wire in place. — **Figure 44.1** Accessing the ureter with a single wire in place. The safety wire can be tented upwards to facilitate access of the ureter by the rigid ureteroscope inferiorly.

Equipment for rigid and semirigid ureteroscopy

Instruments

Although not absolutely required, a rigid or flexible cystoscope is frequently used to place guidewires to facilitate ureteroscopy. Less commonly, guidewires can be placed using the ureteroscope itself. On occasion, however, difficulties associated with an enlarged prostate or edema of the ureter may make cannulation of the ureteral orifice difficult without the wider view of the cystoscope. Difficulties encountered in bypassing an impacted stone can also frequently be overcome by using a rigid cystoscope with a sheath larger than 17 Fr that can accommodate an open‐ended ureteral catheter through which multiple wire types can be exchanged prior to placement of the ureteroscope within the ureter.

Rigid and semirigid ureteroscopes are available in a variety of sizes that range from 4.5 to 12 Fr and have working channels that range from 2.3 to 6.4 Fr [16]. There are typically one or two working channels. With two working channels, a constant flow of irrigation can be maintained despite placement of working elements such as laser fibers or stone retrieval baskets.

Guidewires

Initially developed for vascular procedures, guidewires have become an essential part of upper urinary tract endoscopy [17]. Guidewires are often used as the first means of accessing the ureter and the collecting system. A number of different guidewires are available with different core designs, diameters, and coatings. Selection of a particular guidewire depends upon its intended use.

Guidewires typically have soft, flexible tips to prevent tissue damage [18]. They are generally made up of two components: an outer polytetrafluoroethylene (PTFE) coating, which provides for a hydrophobic surface that is more easily handled, and an inner steel core which determines the rigidity and flexibility of the wire [18]. Nitinol (nickel‐titanium) can be substituted for the inner core and allows resistance to kinking as opposed to the stainless steel core wire which can be permanently bent rather easily [17, 19]. Guidewires range in a diameter from 0.018 to 0.038 inches, with the majority of wires used in ureteroscopy being 0.035 and 0.038 inches. Larger‐diameter wires provide increased stiffness at the potential cost of impaired irrigation flow should the wires need to be passed through a flexible ureteroscope. With the multiple larger diameter working channels of rigid and semirigid ureteroscopes, decreased flow is not typically a concern when flexible ureteroscopy is not contemplated.

Standard stainless steel/PTFE wires and nitinol/PTFE wires are well suited for obtaining and maintaining ureteral access during uncomplicated ureteroscopy. Hydrophilic wires have low‐friction characteristics that are useful for negotiating beyond a ureteral obstruction such as that due to an impacted stone or a ureteral stricture. As hydrophilic wires typically lack the stiffness and friction required for easy handling, they are typically not used as safety wires and should be exchanged for a standard wire once an obstruction has been bypassed. Stiffer wires (Amplatz style) are useful for preventing buckling or kinking of wires while placing dilators and access sheaths [20].

Irrigation devices

Pressure irrigation systems are necessary for visualization in the upper urinary tract as gravity irrigation is typically insufficient to distend the ureter and collecting system through the small working channels of ureteroscopes. Pressure irrigation also helps to clear the endoscopic field of stone fragments, blood, and debris [21]. Due to the risk of systemic absorption from pressure irrigation and/or ureteral perforation, normal saline is the irrigant of choice to prevent electrolyte disturbances [22, 23]

Commonly used commercial irrigation devices are syringe‐style pumps (Single Action Pumping System, Boston Scientific), bulb‐style pumps (Pathfinder, Utah Medical), and hands‐free foot pumps (Flo‐Assist, Nortech). Each of these systems provides pressure irrigation in a pulsatile manner. Bulb pumping appears to be associated with less operator hand fatigue compared to syringe irrigation while syringe irrigation appears to allow finer titration of irrigation flow [24]

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