Abstract
Ureteroscopy (URS) is now the first-line diagnostic and treatment modality for almost all ureteral and intrarenal pathology. Even with the greatly increased range of indications for URS, the rate of complications has steadily decreased. The overall rate of complications is very low, reportedly less than 5%. However, to prevent complications, the best management remains appropriate preparation with proper selection of the patient, technique, and postoperative care. In this chapter, we discuss the indications for URS, describe the techniques used to perform URS to prevent complications, and identify the possible intraoperative and postoperative complications with strategies to successfully recognize and manage them.
Keywords
Ureteroscopy, Ureteroscopes, Intraoperative complications, Postoperative complications, Ureter, Kidney calices, Kidney pelvis, Nephrolithiasis
Key Points
- 1.
Complications of ureteroscopy (URS) are rare.
- 2.
Prevention of complications is the best management.
- 3.
Appropriate patient selection, case preparation, and technique will help to minimize the potential for complications.
- 4.
Always bypass the level of obstruction and establish access to the upper urinary tract with a wire prior to addressing any pathology.
- 5.
Always visualize the actions of your instruments and energy sources, and never force the scope or instrument.
- 6.
If a ureteral injury is suspected, then it is acceptable to abort the procedure, place a ureteral stent, and then return for a second session at a later date.
- 7.
Postoperative complications are often minor and can be managed conservatively.
Introduction
Endoscopic surgery for the diagnosis and treatment of disorders of the upper urinary tract is an important minimally invasive tool in the urologists’ armamentarium. Since 1929, when Young and McKay documented the use of a cystoscope to perform a ureteropyeloscopy in a child, and with Marshall’s first use of a flexible passively deflecting fiberoptic ureteroscope in 1964, ureteroscopy (URS) has continued to progress.
Contemporary indications for URS now include the evaluation and treatment of many conditions of the upper urinary tract including ureteral and renal stone disease, strictures of the ureter, ureteropelvic junction (UPJ) obstruction, intrarenal strictures or calyceal diverticulum, and select upper urinary tract urothelial cell carcinoma (UCC). Even with the greatly increased range of indications for URS, the rate of complications has steadily decreased. This change is partly the result of technologic advances such as the development of smaller ureteroscopes, improvements in energy sources with the holmium laser, and the use of smaller endoscopic tools such as guidewires, access sheaths, graspers, and baskets. In addition, the skill level of urologists has significantly improved in part because URSs comprise index cases for resident education within the United States.
Despite the now routine use of URS, complications do still occur. In an analysis for the Clinical Research Office of the Endourological Society (CROES) URS Global Study Group, the observed stone-free rate in 11,885 patients was 85.6% with a very low overall postoperative complication rate of 3.5%, with the most common complication being fever (1.8%). It should be noted that the majority of the complications described in the literature are based on analyses from renal and ureteral stone surgery. Nevertheless, the information can and should be applied to all cases where URS is used. To prevent complications, the best management remains appropriate case preparation with proper selection of the patient, technique, and postoperative care. In this chapter, we discuss the indications for URS, describe the techniques used to perform URS to prevent complications, and identify the possible intraoperative and postoperative complications with strategies to successfully recognize and manage them.
Patient Selection
Renal and Ureteral Stones
URS has become the de facto gold standard for the treatment of stones at all locations within the ureter. In the kidney, stones up to an aggregate size of 2.0 cm have become routine indications for URS, especially in the lower pole. Larger renal stones may also be addressed with URS but have lower stone-free rates, often require more than one session, and should therefore typically be reserved for percutaneous nephrolithotomy.
Upper Urinary Tract Strictures
Strictures in the ureter, at the UPJ, and intrarenal abnormalities like a calyceal diverticulum are also amenable to URS in selected cases. In the ureter, endoscopic management of strictures is generally limited to those that are nonischemic, nonradiation induced, benign, less than 1.5 cm in length, with minimal ipsilateral hydronephrosis, good renal function, and without prior failed endoscopic attempts. Similarly, for UPJ obstruction, endopyelotomy can be successful for strictures less than 2 cm in length, in the absence of ipsilateral severe hydronephrosis, ipsilateral renal function greater than 25%, and without a crossing accessory renal artery, which is an absolute contraindication. It is also particularly effective as a salvage option following recurrence after an open or laparoscopic repair. Last select intrarenal abnormalities like calyceal diverticulum can be addressed with URS, especially when located in an anterior calyx in the upper or midpole with or without a small associated stone.
Upper Urinary Tract Urothelial Carcinoma
In the management of upper urinary tract UCC, URS is an important modality for both diagnosis and treatment. A diagnostic biopsy can be performed with URS, which is important for determining tumor grade and in treatment planning, especially for those patients with a solitary kidney or considering renal-sparing management. URS ablation of the tumor is an acceptable elective treatment option for patients if the tumor burden can be successfully treated endoscopically and provided they meet strict criteria such as unifocal disease or small volume multifocal disease, small tumor size, low-grade histology on biopsy, noninvasive imaging characteristics, and the ability of the patient to submit to close postoperative surveillance.
Contraindications
As described, appropriate patient selection for each indication is critical to successful treatment but also to prevent complications. Once the patient is appropriately selected for URS, the only absolute contraindication to proceeding is active, untreated infection. Therefore, prior to URS all patients must undergo at least a urinalysis with microscopy, but preferably a urine culture. If the urinalysis suggests infection, or the patient has a culture-proven urinary tract infection, then this must be treated prior to endoscopy.
A relative contraindication is an uncorrected bleeding diathesis or ongoing anticoagulation therapy, which cannot be safely discontinued. Despite this, it is still possible to perform URS in these situations, as long as the risks and benefits are clearly discussed with the patient and the medical team prior to proceeding.
Preparation
Preoperative Assessment
As with any surgical intervention, appropriate careful preparation is mandatory. In the anticipation of URS, the first step in patient preparation is a history and physical exam. A biochemical evaluation with serum and urine laboratory tests may also be carried out, and as stated previously, a urinalysis or a urine culture is the minimum standard.
Once this is completed, then depending on the pathology to be evaluated or treated, it is often necessary to proceed with an imaging study. For patients suspected of having nephrolithiasis, a noncontrast CT (NCCT) is the recommended first-line imaging modality for an adult nonpregnant patient. However, a renal bladder ultrasound (US) may be an alternative with an NCCT reserved if a stone is suspected in the setting of acute flank pain. For a patient with a ureteral stricture or UPJ obstruction, then a contrast-enhanced CT with delayed, excretory phase imaging (CT urography) to opacify the urinary tract is recommended. This is particularly important for the diagnosis of an upper urinary tract UCC, where CT urography is the recommended first-line imaging modality. Alternative imaging strategies include MR urography if a patient has an absolute or relative contraindication to a CT, such as with an iodinated contrast allergy.
After the diagnosis is made based on history, physical exam, laboratory tests, and imaging studies, then a discussion regarding the appropriateness of URS in the context of the patient’s pathology, comorbidities, and provider’s skill with URS should be conducted. If URS is selected, then depending on local or regional practice patterns, a preoperative medical evaluation for fitness for anesthesia can be performed.
Perioperative Preparation
Once in the operating room, but prior to the start of the procedure, appropriate antimicrobial prophylaxis is necessary. A single preoperative dose or duration of less than 24 hours is sufficient. The antibiotic should be tailored to preoperative cultures, local resistance patterns, or based on guideline recommendations. The timing of administration relative to scope insertion/incision should reflect the pharmacokinetics of the agent selected, which is particularly important for the fluoroquinolones that need to be given 120 minutes prior to incision (as opposed to 60 minutes for most other drugs).
Prophylaxis to prevent thromboembolic events is an important consideration for all surgical patients. In the recent CROES URS Global Study Group, the rate of thromboembolic events was 0.02%. This is an exceedingly rare complication and, therefore, the recommendation is against pharmacotherapy or mechanical prophylaxis, other than early ambulation for patients at very low risk. However, individual patient factors should be taken into consideration, especially if the risk is high, and then pharmacotherapy or mechanical prophylaxis should be strongly considered. It should be noted that despite these recommendations intermittent pneumatic compression is often still used in routine clinical practice.
Appropriate patient positioning is a vital component of the pre-procedure preparation. It provides for both patient and provider comfort. In the majority of instances URS is performed in the dorsal lithotomy position. This position, especially in thin patients and in those undergoing prolonged procedures, can result in neuropraxia, most often to the peroneal nerve, and compartment syndrome, which can lead to rhabdomyolysis. Therefore it is important that the patient is appropriately positioned with all pressure points padded, the joints not hyperextended, and adequate perfusion is permitted and maintained to the extremities. Of course, there is no substitute for close clinical monitoring during prolonged cases, especially in those patients at risk.
Last appropriate preparation does not rest solely with the urologist. A coordinated effort is required from all members of the operating room team. Formal preprocedural briefings are becoming routine and have been demonstrated to improve inter-team collaboration, prevent complications, and enhance patient outcomes. Furthermore, centers with a high case volume for URS have increased stone-free rates with decreased retreatment, readmission, and complication rates. This is likely a surrogate for the presence of integrated, coordinated processes surrounding the preoperative, intraoperative, and postoperative care of patients after URS.
Technique of Upper Urinary Tract Endoscopy
Cystoscopy and Initial Upper Urinary Tract Access
The initial step of upper urinary tract endoscopy is to perform a proper cystoscopy. This allows for examination of the bladder for concomitant pathology. Once the cystoscopy is complete and no lower urinary tract intervention is deemed necessary, then access to the upper urinary tract may be performed. This starts with identification and intubation of the appropriate ureteral orifice.
This step is most often performed with a guidewire. There are several available on the market of varying diameters and several with a hybrid technology. We prefer to use a hybrid 0.038″ straight Sensor PTFE-nitinol guidewire with hydrophilic tip. We feel that this hybrid wire combines the flexible, delicate tip of a nitinol hydrophilic wire, which is useful for bypassing points of obstruction, with the security and strength of a nitinol core PTFE-coated wire for instrument passage. Thus, it has the theoretical advantage of preventing the use of multiple different wire types.
Negotiating the Obstruction
The wire is then advanced under fluoroscopic guidance up to the point of obstruction or, if possible, passed into the renal pelvis ( Fig. 27.1 ). If resistance is met during advancement of the wire, then a 5Fr open-ended ureteral catheter can be placed over the wire up to the point of resistance. The wire can then be removed. A retrograde pyelogram can be performed through the catheter to outline the ureter and collecting system in order to identify the area of concern ( Fig. 27.2 ). If there is complete obstruction on the retrograde pyelogram, then an alternative access to the upper urinary tract may be necessary, such as a percutaneous access.
However, if this is not the case, then there are several strategies to negotiate the wire past the level of obstruction. If the issue is kinking of the wire, then the 5Fr open-ended ureteral catheter can be left in place to provide additional support. If, however, the wire continues to kink or coil, then the next step is to try a hydrophilic guidewire, which has the nitinol core of the guidewire but with a lubricated coating allowing for ease of passage and flexibility. These can be either straight or angled. By using these wires, it is often possible to bypass areas of narrowing or tortuosity not amenable with the standard or hybrid guidewire. It should be kept in mind that serial unsuccessful attempts at wire passage across an area of obstruction can lead to further injury, complicating future management. Therefore, if this is encountered, then it is reasonable to abort the procedure and consider alternative access to the upper urinary tract or decompression with percutaneous access.
Maintaining Access
If a hydrophilic guidewire is used and placed into the collecting system, then this wire should be exchanged for the stiffer guidewire prior to instrument or URS placement. This can be done with a 5Fr open-ended ureteral catheter placed above the level of obstruction under fluoroscopic guidance. As stated previously, the hydrophilic guidewire has lubricity and is flexible, making it prone to migrating if used for manipulation. Once a guidewire is situated in the kidney, above the level of obstruction, then it is possible to proceed with endoscopy. However, if turbid or purulent urine is encountered at this, or any point, then it is mandatory to abort the remaining procedure, place a ureteral stent for decompression, and then treat accordingly with appropriate antibiotics.
Although a single wire may suffice, it is often prudent to place a second, safety wire to ensure access to the collecting system at all times, especially in the event of ureteral injury ( Fig. 27.3 ). This is often done using a dual-lumen ureteral access catheter or an 8/10Fr dilator/sheath set. This is placed over the original, working wire into the distal ureter, and then a second, safety wire is placed through the device into the collecting system under fluoroscopic guidance. Both devices are also useful for gently dilating the ureteral orifice and intramural ureter to later accommodate the URS.
Entry of the Ureteroscope
If a rigid URS is required, which we typically limit to the distal one-third of the ureter below the crossing of the iliac vessels in men and the mid- to proximal ureter in women, then placement of a second wire can be done under direct visualization. A nice strategy is to place the second wire through the scope as the scope is advanced up the ureter, thereby “railroading” the scope between the two wires. Each wire acts to straighten and stent open the ureter as the scope passes by for improved visualization.
If a flexible URS is used, then either an instrument, such as a ureteral access sheath, or the URS itself can be advanced over the wire. This is usually done under fluoroscopic guidance. We prefer to use a ureteral access sheath for larger stone burdens (>1.0–1.5 cm), as they have demonstrated improved entry/reentry of the scope, decreased intrarenal pressures, as well as a suggestion of improved clinical outcomes with a lower stone-free rate and reduced infectious complications but without increasing the rate of ureteral injury.
At any point, if the instrument or scope cannot be advanced due to a narrowed ureter, then the options include serial or balloon dilation of the ureter or placement of a ureteral stent with a plan to return for a second attempt at ureteroscopy. Typically, the distal ureter or a short segment of the ureter is dilated, only up to 12Fr. In our practice, we advocate for placement of a ureteral stent ( Fig. 27.4 ) over ureteral dilation. This will allow for passive dilation of the ureter. A repeat attempt at access in a delayed setting is successful in the vast majority of cases. We do not recommend using serial or balloon dilators, as we feel this is associated with a relatively high complication rate, although it does involve the need for a second surgery.
Endoscopy
Once the scope reaches the point of the pathology (stone, stricture, or tumor), then work can begin. The actual procedure will depend on the problem to be addressed. However, irrigation is a key component of all upper urinary tract procedures. Proper irrigation will allow for maximal visualization to facilitate safe and effective performance of the procedure. Saline should always be used for irrigation with URS due to the risk of hyponatremia with hypotonic solution. There are advocates for both passive and active irrigation systems. Active (hand pump) irrigation systems reportedly have an increased risk of stone migration with a suggestion of increased risk of pyelovenous and pyelolymphatic backflow, which can lead to infectious complications. We prefer to use a passive irrigation system with pressure bags. However, we acknowledge that for challenging cases with poor visualization it may be necessary to use an additional active irrigation mechanism to improve the field of view.
Intraoperative Complications
The overall rate of intraoperative complications is very low ( Table 27.1 ). In the contemporary CROES multicenter, multinational clinical registry of URS, the rate was 5.5% in over 11,000 patients. All of these were related to the ureter. Several factors were also shown to modify the risk of intraoperative complications. However, preoperative ureteral stent placement was not one of them. In fact, there was no difference in intraoperative complications with or without pretreatment ureteral stent placement in either renal or ureteral stones.
| Complication | Risk Factor a | Etiology | Rate b | Management |
|---|---|---|---|---|
| Ureteral bleeding | Multiple ureteral locations Low-volume center | Dilation Misfired energy Mucosal injury | 1.4% | Observation Ureteral stent |
| Ureteral erosion or false passage | Unknown | Wire placement Scope manipulation Misfired energy Instrument deployment Stone removal | Unknown | Observation Ureteral stent |
| Ureteral perforation | Midureteral location Low-volume center | Wire placement Scope manipulation Misfired energy Instrument deployment Stone removal | 1.0% | Ureteral stent |
| Ureteral intussusception or avulsion | Low-volume center | Entrapped stone removed with excessive force | 0.1% | Nephrostomy tube Delayed repair |
A grading system developed by the American Association for the Surgery of Trauma exists for traumatic injuries. This ranges from contusion (grade I) to complete transection with extensive devitalization (grade V). However, this is not applicable to iatrogenic injuries. Instead, a specific classification system was developed for injury from URS. In this scale, damage to the ureter ranges from wall petechiae (grade 0) to mucosal erosion (grade 1) to perforation with or without advential preservation (grade 2 and 3) to total avulsion (grade 4) ( Fig. 27.5 ). Although this continuum when divided as either low grade (grade 0 and 1) or high grade (grade 2, 3, and 4) is useful as a framework with which to discuss iatrogenic ureteral injuries from URS, it is rarely used clinically.
Ureteral Bleeding
Bleeding was the second most common complication in the CROES registry at only 1.4%. However, it was more common when stones were treated in multiple locations (2.5%) as compared to only a single location in the proximal (0.9%), mid- (1.3%), or distal (1.3%) ureter. Similarly, case volume also influenced the rate. Low-volume centers had more than twice the rate as high-volume centers (2.5% vs 0.9%). Minor bleeding can occur during ureteral dilation, due to misfired energy from a laser, or at sites of pathology, such as along the mucosa of an impacted stone or from a papillary urothelial tumor. Additionally, wires advanced too far can pierce the collecting system and enter the renal parenchyma, leading to minor bleeding. The rate of subcapsular hematoma is estimated at 0.36–0.4%. This minor bleeding is usually self-limited. However, it can reduce visibility if it enters the collecting system, and active irrigation may be necessary for a short period of time. More extensive bleeding is very rare, although it can occur, especially from a large papillary urothelial tumor, or following endopyelotomy for a UPJ obstruction with rates as high as 8–9%. Rare causes of massive ureteral bleeding include endometriosis and ureteroarterial fistulas. If bleeding is severe and persistent or visualization is poor, then it is prudent to abort the procedure and place a ureteral stent. This is usually sufficient to tamponade the bleeding. However, it may be necessary to consider further intervention such as angioembolization or, rarely, nephrectomy in select situations. A blood transfusion after ureteroscopy is very rare, estimated at only 0.2%.
Low-Grade Ureteral Injury
Low-grade ureteral injuries consisting of either a contusion with wall petechiae, a superficial mucosal erosion, or false passage are likely very common during URS. However, the exact incidence is unknown. In a multi-institutional cohort, there were a total of 311 (86.6%) patients who experienced a low-grade ureteral injury after URS with the use of a ureteral access sheath. The reporting of this complication is absent from other studies, particularly the comprehensive CROES URS registry. Nevertheless, as it is commonly encountered in routine clinical practice, recognition and treatment are still important. The mucosal erosion typically occurs during wire placement, scope manipulation, misfired energy, instrument deployment, or stone removal. After the injury, it is still possible to complete the procedure, but extra care must be taken not to convert a mucosal erosion to a perforation. This can best be avoided by moving the action of the procedure away from the site of injury. This is especially true if stone fragmentation is undertaken, as stones displaced outside the ureter are associated with the later development of ureteral strictures. Furthermore, if at all possible, the site of injury should not be crossed repeatedly, as is common practice with basket stone removal. At the conclusion of the procedure, or if there is concern for a worse ureteral injury, then it is reasonable to abort the procedure and place a ureteral stent. The late development of a ureteral stricture after URS is very rare, with a contemporary reported rate of only 0.3%.
High-Grade Ureteral Injury
High-grade ureteral injuries, although potentially devastating, are now increasingly rare. These include ureteral perforation, intussusception, and avulsion. As stated previously, perforation involves injury to all layers of the ureter with either the adventitial or the periureteral fat containing the area of damage. The perforation, as with mucosal erosion, can occur with wire placement, scope manipulation, misfired energy, instrument deployment, and stone removal. The current accepted rate of perforation is 1%. It is more common in midureteral locations (1.6%) than in the proximal (1.1%), distal (0.7), or multiple locations (1.1%). Similarly, a low-volume center is associated with an increased rate as compared to a high-volume center (2.3% vs 0.8%, respectively). Surprisingly, the rate was not changed with or without use of a ureteral access sheath (1.2%). Once a perforation is identified, then the procedure should be aborted and a ureteral stent should be placed. The procedure can then usually be accomplished in a delayed fashion after several weeks with ureteral stent drainage. Again, the late development of a ureteral stricture is very rare.
Intussusception is also a rare event where the mucosa telescopes inward, folding in on itself, and separating from the underlying stroma. This is often associated with antegrade or retrograde basket stone removal, where the stone entrapped within the basket is too large to be removed from a narrowed, unaccommodating ureter. The force of removal shears the ureteral mucosa, pulling it inward with the basket. This is one reason why blind basketing is prohibited. The exact incidence of this complication is unknown, as it is likely not reported separately from avulsion.
Ureteral avulsion is the most feared and devastating complication of URS. Thankfully, it is exceedingly rare. It is reported to occur in only 0.1% of cases. The location of treatment (proximal, mid, distal, or multiple locations) does not seem to influence the rate of avulsion. However, case volume does. The rate was over 12 times higher in low- as compared to high-volume centers (0.5% vs 0.04%). Similarly to intussusception, ureteral avulsion typically occurs when a stone too large to be removed is engaged within a basket and then excessive force is used to remove it. During removal, the ureter becomes entrapped, tears from its attachments, and then is externalized with the basket and scope as they are withdrawn. If this is recognized, then the procedure must be aborted immediately. Another possible complication related to intussusception and avulsion is the “scabbard effect,” where the proximal scope, which is larger in diameter than the tip, becomes wedged in the narrower distal ureter, resulting in friction and dissociation of the mucosa. This is similarly observed when small stone fragments get trapped along the length of the scope.
For intussusception, avulsion, and the scabbard effect, proper technique is the best prevention. When stone removal is undertaken, the mucosal wall must always be visualized. If resistance is met at any point, then further removal must be aborted. The ureter should then be inspected for integrity. Again, blind basketing without direct visualization should be avoided, and excessive force should never be used. If, however, intussusception or avulsion does occur, then placement of a ureteral stent is likely not possible, nor will it provide for adequate drainage as the ureter is completely devascularized. Therefore, it is prudent to urgently place a nephrostomy tube. Formal open or laparoscopic surgical repair will be required. The type of repair will depend on the location and extent of the injury, comorbid medical conditions, and the experience of the surgeon. The repairs range from simple ureteroneocystotomy to psoas hitch or Boari flap to ileal interposition to autotransplantation or nephrectomy. Therefore we do not advocate for immediate repair but rather a delayed approach for time to adequately discuss the options with the patient.
Failure and Conversion
Failure is defined as an inability to access the ureter or stone during initial treatment. Both failure and conversion are reported as complications in modern series with overall rates of 1.6% and 0.1%, respectively. There is evidence that stone location and procedure volume do influence the rates. Failure is more common in a proximal (2.8%) location than in a mid- (1.9%), distal (0.7%), or at multiple (0.7%) locations. Similarly, it is more common in low- as compared to high-volume centers (2.3% vs 1.5%). This was also observed for the rate of conversion (0.4% vs 0.01%). Although both failure and conversion are listed as complications, in certain circumstances they should be viewed as appropriate treatment, especially if further attempts at ureteroscopy would lead to injury.
Instrument Failure
Instrument failure can include any piece of equipment necessary to safely and adequately perform URS. This can be the ancillary equipment such as the operating room table, positioning devices, and fluoroscopy unit; the endoscopic tools such as the laser generation unit, laser fiber, and stone retrieval basket; and the scope itself. However, we will focus only on the endoscopic tools, particularly the stone retrieval basket, and the scope. The exact rate of endoscopic tool failure and/or breakage is not known. It is likely not all that common, but it is important to be familiar with strategies should it occur. Scope durability, however, is well defined and quantifiable, which allows for appropriate planning and preparation.
Stone Retrieval Basket Failure.
The stone retrieval baskets used for URS are now miniaturized to 1.9Fr for improved irrigation, tipless to prevent mucosal abrasions, and composed of nitinol, allowing for maximal flexibility without compromising strength. In fact, they are the only basket recommended by current EAU guidelines for stone extraction. Despite their clinical utility, the baskets remain susceptible to damage, especially when laser energy is directly applied. Therefore when a basket is broken, it should be immediately disengaged from the stone. The basket can then be withdrawn into the scope or, if not possible, then carefully withdrawn out of the ureter under direct visualization. It is imperative to always be cognizant of the end of the basket and the damaged or disrupted tine to prevent its catching on the ureter.
The other possible scenario involving a basket is if it is used to grasp a stone larger than the ureter will accommodate for removal. As stated previously, this is the condition where ureteral intussusception or avulsion can occur if excessive force is applied. Typically, the basket will be able to be disengaged from the stone, but sometimes this is not possible. In this case, one strategy is to disassemble the basket. Usually, the external end of the basket housing can be unscrewed (or the basket wire itself cut), which allows the outer sheath of the basket to be removed through the scope while the internal basket wires remain in place. This often increases the opening diameter of the basket wires, facilitating disengagement from the stone. If this occurs, then it can be removed through the scope with the stone left in place.
If this does not disengage the basket from the stone, then two additional strategies are possible. The first is to pass a 200-micron laser fiber through the working channel alongside the dissembled basket. The stone can then be fragmented in situ while engaged within the basket. Once the stone is in pieces less than 2–3 mm, the basket can usually be separated from the stone and removed. When employing this strategy, it is important to know that irrigation through the scope will be minimal and also that maneuverability of the scope must be limited as it is still engaged to the basket and stone. The alternative option is to remove the scope entirely over the disassembled basket and then reinsert it alongside the basket up to the level of the stone. The laser can then be introduced and the stone fragmented, allowing for safe basket removal. In fact, a proprietary basket, termed the “Escape” basket, is a 1.9Fr device specifically designed to engage the stone and then allow passage of a 200-micron laser fiber through the basket to facilitate fragmentation of the stone.
Scope Damage and Durability.
Damage to the URS is primarily localized to degradation of the lens/fiber optic bundle, channel perforation, or loss of deflection. In a survey of the four major URS manufacturers (ACMI, Olympus America, Karl Storz, and Richard Wolf) in 2005, repairs to the URS were to the working channel, shaft of the scope, deflection mechanism, and the eyepiece in 52%, 27%, 15%, and 8% of cases, respectively. The mechanism was attributed to the laser in 42% of the cases with damage to the working channel, 20% of the cases with damage to the body of the shaft, 20% of the cases with damage to the optical fibers, and 45% of the cases with damage to the deflection mechanism. Other top causes for the damage at each site included instrument insertion/extraction, extreme bending, sterilization, and storage.
By understanding the common mechanisms of damage to the URS, strategies aimed at preventing or mitigating them can be designed and implemented to improve the longevity of each scope. In particular, avoiding firing of the laser in close proximity to the tip of the scope or within the working channel will prevent damage to the fiberoptic bundles and working channel. Similarly, not deploying endoscopic devices when the scope is at extreme degrees of deflection will also preserve the working channel.
Durability represents the number of repairs over the total number of cases performed. In a contemporary series with a modern third-generation fiber-optic URS model (Olympus URF P5), all 643 cases at a single ambulatory surgical center in the United States were examined during a 3-year period (2011–2014). There were 31 repairs performed on the four flexible URSs for an average of 21 procedures between repairs. With the new fourth-generation digital URS there is a suggestion of even superior durability. In a retrospective analysis at a single institution with a single surgeon using a single model of digital URS (Storz Flex-Xc) from 2012–2013, the three scopes were able to be used for 96, 151, and 159 cases, respectively, prior to repair.
Durability varies by scope manufacturer, practice location, surgeon, sterilization technique/team, and case mix. Therefore, it is important to have an understanding of the average durability of your scope. This will allow for proper inventory so that in every case, a clean, functional scope is always available. In our experience, this is best achieved through standardization of staff, processes, and equipment in consultation with manufacturer representatives. The recent introduction of a single-use (disposable) digital ureteroscope into the market provides an alternative option that eliminates many of the issues related to durability and reprocessing and, thus, may increase the value of the procedure.
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