Changing Trends in the Use of Ureteroscopic Instruments from 1996 to 2008

Introduction

A dvances in endoscopic technology have led to a revolution in the management of upper tract pathology. The development of semirigid, fiberoptic, and actively deflectable, flexible ureteroscopes has allowed urologists to gain access to all areas of the collecting system. Improvements in ancillary instruments have expanded the realm of cases amenable to ureteroscopic management. A wide range of pathology is now routinely treated endoscopically, including calculi, transitional-cell carcinoma (TCC), and ureteropelvic junction (UPJ) obstruction.

Despite this evolution in the field of endourology, there are few reports describing specific change adopted by urologists that have come as a result. We examined the progression of single surgeon's clinical practice over a 12-year period, noting differences in ureteroscopes, ancillary equipment, and indications for surgery.

Methods

The records of 1181 patients undergoing ureteroscopy by a single surgeon were reviewed. Consecutive patients from the years 1996 (n = 200), 1998 (n = 179), 2000 (n = 198), 2002 (n = 127), 2004 (n = 137), 2006 (n = 200), and 2008 (n = 140) were included in the study. The number of patients in each year varied by the availability of the study surgeon or associate in each period. Patients remained grouped by their respective years for comparison. Compared variables included the indication for surgery, type of anesthesia, method of ureteral dilation and stabilization, specific ureteroscopes used, type and number of working instruments employed, and the method of postprocedure ureteral drainage.

Results

Table 1 lists the most common indications for ureteroscopic surgery, including urolithiasis, TCC, UPJ obstruction, and hematuria. Other indications included ureteral stricture, foreign body removal, infundibular stenosis, caliceal diverticulum, pain, positive cytology or fluorescence in situ hybridization (FISH), ureteroileal anastomosis stricture, and radiographic filling defect. An increase in the number of cases performed for TCC inversely paralleled the decreasing trends in cases performed for calculus disease and UPJ obstruction (Table 1).

General anesthesia was used in 88.9% of the cases in 1996 and has increased since that time. Although monitored anesthesia care initially comprised the minority of cases in earlier years, its use has largely been supplanted by laryngeal mask airway (LMA). Since 2000 general anesthesia has been used in over 99% of the ureteroscopic cases.

Specific ureteroscope use is listed in Table 2. The most common semirigid ureteroscope was the 6.9F rigid, employed in over half of all cases across all years studied, whereas the dominant flexible ureteroscope changed over this time. Initially the most commonly used flexible ureteroscope, the AUR-7, was largely replaced by the DUR-8 in 2002. Most recently the 7.5F FlexX2 ureteroscope (Karl Starz Endoscopy America, Inc., Culver City, CA) has become the endoscope of choice at our institution. Since 1998 it has been more common to employ multiple ureteroscopes during endoscopic procedures (Table 2).

Methods of ureteral dilation included preoperative stent placement, graduated dilators, balloon dilation, passage of a small rigid endoscope with a tapered shaft diameter, and passage of a 10F dual lumen catheter. Some form of ureteral dilation was performed in the majority of cases during all years studied, with preoperative stenting and passage of a small rigid endoscope being the most common throughout the study period (Table 3). For ureteral stabilization, a guidewire was used in the large majority of patients for all years, with more recent employment of ureteral access sheaths seen in a small number of cases (Table 3).

Many types of working instruments have been employed at our institution. For ease of comparison, instruments sharing a similar mechanism have been grouped. Wire prong graspers include both three-prong and rarely two-prong graspers. Helical stone baskets include three-wire, four-wire, 1.9F, and three-wire triangular nitinol (N-Force [Cook Urology, Cook Medical, Inc., Bloomington, IN]) baskets. Nitinol wire baskets include predominantly the N-Circle (Cook Urology) and Dimension (Bard Urology, Covington, GA) baskets. Stone impact devices include the Brown Pneumatic Impact Device (now Boston Scientific, Natick, MA), the Lithoclast (EMI), and the LMA Stonebreaker (LMA Urology Suisse Ltd, Gland, Switzerland). Baskets for upper tract tumor cases are mainly flat-wire design (Segura) but also include four-wire, snare, three-prong grasper, and 1.9F baskets. Both 3F round cup forceps (Cook Urology) and the Piranha (Boston Scientific) forceps are included under 3F forceps. Electrosurgical devices include the RiteCut (Olympus-GyrusACMI, Southborough, MA), Hulbert pencilpoint (Cook Urology), and 2F electrode (Olympus ACMI) devices. Changing instrument trends for particular indications are shown in Table 4.

Discussion

Ureteroscopy involves the transureteral endoscopic diagnosis and treatment of upper urinary tract disease. Originally limited to cases involving the most straightforward distal ureteral pathology, technological advances in the field of endourology have expanded the realm of cases amenable to ureteroscopic management, making these surgeries a cornerstone of modern urologic practice. Urologists today are able to treat calculi, neoplasms, and obstruction throughout the upper urinary tract. The number of cases considered for ureteroscopic management has also increased. For example, early indications for the treatment of urolithiasis were limited to distal stones. Using modern ureteroscopes, lithotriptors, and retrieval devices, intrarenal calculi including lower pole stones ¹ and even staghorn calculi ² are able to be treated successfully by this approach. We have previously noted the change in the success of ureteroscopic stone treatment with major changes in instrument availability. ³

In our series, the treatment of upper tract neoplasms has become a more prominent surgical indication during the observation period (Table 1). This may reflect our particular referral pattern, rather than an indication of increasing upper tract tumor incidence. The current author's practice is weighted more heavily toward upper tract TCC, and the option for nephron-sparing management and ongoing surveillance for tumor recurrence may account for the increase in the overall proportion of such cases from 33% in 1996 to 51.4% in 2008. Biopsy instruments, including forceps and metal flat-wire baskets, have been consistently used for obtaining pathologic specimens. Holmium and neodymium:yttrium-aluminum-garnet (YAG) lasers are the ablative device of choice. Use of a 2F electrode has remained steady because of its minimal resistance to ureteroscopic deflection, which proves useful for lesions in difficult locations.

The percentage of ureteroscopic cases performed for gross hematuria has remained low but relatively stable, while the incidence of urolithiasis and UPJ obstruction procedures has declined. The former may reflect the overall shift toward tumor cases, whereas the latter is possibly because of the superior long-term success of pyeloplasty, particularly with a laparoscopic approach. ^4,5

Flexible ureteroscopes have played an increasingly prominent role in upper tract endoscopy as the focus has shifted from the distal ureter to the intrarenal collecting system. The particular choice of ureteroscope has changed over time, reflecting advancements in size, deflection, image quality, and durability (Table 2). Although it is rare to require more than 180 degrees of deflection to reach all calices, the resistance to deflection caused by working instruments can be compensated by a flexible endoscope with 270 degrees of deflection. Newer digital video ureteroscopes offer excellent images, but unfortunately suffer from interference by some lasers and a larger outer dimension than fiber scopes.

Grasso and colleagues ⁶ have advocated direct ureteroscopic access through the urethra and bladder directly into the ureteral orifice. In our experience, passage of a flexible ureteroscope over a guidewire allows for smooth and straightforward positioning in the upper urinary tract (Table 3). Early ureteral access sheaths were not used because of their tendency to bend or kink, but newer designs have provided the ability to quickly and repeatedly place the flexible ureteroscope into the renal pelvis while minimizing trauma to the urinary tract. This is especially useful when retrieving multiple stone fragments after lithotripsy. ⁷ When it is prudent to inspect the entire ureter, a rigid ureteroscope is placed first.

Early in the history of endourology, ureteral dilation was necessary because of the larger endoscopes available. The use of smaller ureteroscopes has allowed ureteral placement without dilation in most cases. In our practice, a 10F dual lumen catheter is initially placed over the safety guidewire to introduce contrast or to place a second guidewire. Alternatively, during diagnostic cases, a small rigid endoscope may be passed first under direct vision using a no-wire technique to prevent inadvertent disturbance of urothelial abnormalities, resulting in dilation of the ureter from 6.9F at the tip of the endoscope to the larger proximal shaft (8.3 or 10F). It is not clear whether dilation would have been necessary without such maneuvers. Active dilation using graduated dilators or balloon dilators has been consistently performed in only a fraction of cases since 1996 (Table 3).

Studies have shown that the routine placement of ureteral stents after uncomplicated ureteroscopic surgery is unnecessary, ⁸ and in our practice such patients were left without a stent or catheter. However, given the high incidence of recurrent tumors and complex stone cases in our practice, the majority of our patients did require postprocedural drainage. Typically a double-pigtail ureteral stent was used for this purpose. There was a tendency to place open-ended catheters after upper tract tumor resection, to allow for instillation of intrarenal chemotherapy in the recovery room.

There has been a marked change in the availability and use of working instruments over the study period. When endoscopic techniques are employed for UPJ obstruction, endoluminal ultrasound has proven a valuable adjunct to better map the anatomy and diagnose crossing vessels before cautery or laser endopyelotomy. ⁹ The use of electrosurgical devices has been replaced by holmium laser in our practice.

One of the more significant changes has been the divergence in the devices used for calculi and upper tract tumors. During earlier years, wire prong graspers and helical baskets were commonly employed for both cases. Although useful for the biopsy of papillary tumors, these baskets often proved less than ideal for stone extraction because of their difficulty in releasing the stone. The stainless steel wires are prone to deformity, resulting in inadvertent stone entrapment. Wire prong graspers were useful because of their reversible grasp, but stone retrieval was suboptimal given its less reliable grasp of stone fragments. The introduction of nitinol baskets, particularly suited to stone manipulation and release, represented a major change in the endoscopic approach to urinary calculi. ¹⁰ These baskets offer excellent retrieval and release capabilities. ¹¹ Their tipless design makes them particularly well suited for caliceal stones. Its resiliency prevents kinks and deformity during use, making irreversible stone entrapment less likely. Recently designed instruments now allow deflection of the wires, which provides another dimension in the retrieval and release of calculi.

In cases of upper tract tumors, flat-wire baskets maintain an important role for biopsy and large tumor debulking. These instruments can provide a larger tissue sample than cup forceps. Given the small size of many upper tract tumor recurrences, the forceps remain an important diagnostic tool across all years studied (Table 4).

Intracorporeal lithotripsy remains central to endourologic practice. Stones too large for simple extraction require fragmentation for successful clearance. ¹² The holmium laser is our first choice, given the flexibility afforded by modern laser fibers and its effectiveness against all stone types. ¹³ Current generation electrohydraulic lithotripsy probes offer less resistance to active ureterosocpe deflection than laser fibers and have been shown particularly effective against even large intrarenal calculi. ¹⁴ It use has remained infrequent but consistent in the observation period. The use of impact devices remains limited to rigid endoscopes because of their semirigid impact tips. Their role is predominantly in the setting of lower ureteral stones, which have become very limited in this referral practice.

Conclusion

Over the past 12 years, there have been numerous technological advancements in ureteral endoscopy. The incorporation of new ureteroscopes and ancillary instruments in the clinical setting has increased the scope of endourologic practice. There has been a trend toward smaller, actively deflectable, flexible ureteroscopes, intrarenal procedures, wide application of lasers, and a near universal shift toward nitinol baskets for urolithiasis cases.