Ureteroscopy


Continuing Education Activity

Ureteroscopy is one of the most commonly performed procedures by urologists. It is primarily performed for urinary stone disease of the ureters or renal pelvis, but can also be used to diagnose and treat various ureteral and upper urinary tract lesions such as ureteral strictures and urothelial carcinomas. This activity reviews the indication, workup, and the role of the interprofessional team for patients who undergo ureteroscopy.

Objectives:

  • Identify the indications for ureteroscopy.
  • Describe the technique of ureteroscopy.
  • Outline the appropriate evaluation of the potential complications of ureteroscopy.
  • Discuss interprofessional team strategies for improving care coordination and communication to advance ureteroscopy and improve outcomes.

Introduction

Ureteroscopy is a powerful tool at the urologist’s disposal for both diagnostic and therapeutic interventions. It is the endoscopic key to the upper urinary tract. As with many great discoveries, its origin was an accident: in 1912, during a pediatric procedure for correction of congenital posterior urethral valves, Hugh Hampton Young inadvertently passed a rigid pediatric cystoscope into the patient's dilated ureter.[1] In the decades that followed, the potential for ureteroscopy remained largely unrealized. Initially, pediatric and juvenile cystoscopes were used for distal ureteroscopy in women, and then in men once longer, thinner instruments became available. With the addition of working channels, ureteroscopes transcended from the realm of the purely diagnostic to the therapeutic.[2]

Karl Storz introduced the first rigid ureteroscope in 1980. It was 12 French in size with dual working channels, 50 cm long and awkward to use, but it worked. In the 1980s, Olympus adapted a pediatric bronchoscope to produce one of the first deflectable, practical, flexible ureteroscopes, allowing for greater ease of access to the renal pelvis and calyces.[3] It was not until 1989 that semi-rigid scopes became available, which allow up to two inches of flexion without fracturing or any significant distortion of the visual image.[4]

With advances in ureteroscope and camera miniaturization, improved optical systems, digital video capability, laser lithotripsy, smaller ureteral stone baskets and dual working channels allowing for continuous pressurized irrigation for enhanced visualization, ureteroscopy has achieved the necessary imaging capability, versatility, precision, reliability, and safety to become a standard part of modern urological practice.

Ureteroscopy is commonly used to diagnose and treat kidney and ureteral stones, ureteral strictures, and urothelial cancers. Importantly, its evolution was associated with the parallel development of holmium laser technology, which can be used in rigid, semi-rigid, and flexible ureteroscopes. Urological lasers achieve efficient fragmentation of all stone types and can treat urothelial tumors with vaporization or ablation.[5] The following will provide an overview of ureteral anatomy and practical considerations for the application of ureteroscopy including indications, contraindications, equipment, operative technique, practical usage tips, and complications.

Anatomy and Physiology

The ureters course downward and medially, connecting the ipsilateral renal collecting system to the bladder and propelling urine toward the bladder through peristaltic contractions. The ureter is generally 22 to 30 cm in length in the adult, with variability generally, but not always, corresponding to body height.[6] For descriptive purposes, the ureters may be divided as: 

  • Abdominal: renal pelvis to the iliac vessels
  • Pelvic: iliac vessels to the bladder 

Alternatively, into three segments: 

  • Upper: renal pelvis to the upper border of the sacrum
  • Middle: upper to the lower border of the sacrum, along the iliac vessels 
  • Lower: lower border of the sacrum to the bladder

 There are three sites of anatomical narrowing along the ureter’s course that are clinically significant, as these are where calculi will most often obstruct the ureters. From proximal to distal, the sites are:[7] 

  • The ureteropelvic junction (UPJ)
  • The crossing of the ureter over the iliac vessels
  • The intramural ureter at the ureterovesical junction (UVJ), where the ureter is the narrowest and which may require dilation before the introduction of larger-caliber instruments

The blood supply to the ureter stems from multiple vessels. Generally, the upper ureter receives its blood supply from the medial aspect, whereas the pelvic ureter receives it laterally. The upper ureter is supplied by branches of the renal, gonadal, renal polar, capsular and adrenal arteries. The pelvic ureter is supplied by branches of the common iliac, external iliac, gluteal, superior vesical, deferential, vaginal, and middle rectal arteries. In general, the most significant portion of the arterial supply comes from the renal pelvis for the upper or proximal ureter and the bladder for the pelvic or distal ureter. The venous drainage system mirrors the arterial distribution. 

Of clinical significance, the iliac region of the ureter is poorly vascularized. Therefore, an incision or ureteral injury in this area may result in poor healing. All the vessels that supply the ureter anastomose to form a plexus that runs within the ureteral adventitia. Therefore, the ureter can generally be mobilized from surrounding tissues without compromising its blood supply as long as the adventitia remains intact.[8] 

The muscularis layer of the ureter was traditionally thought to be comprised of three layers: two longitudinal layers separated by a circular layer. However, more recent studies indicate a spiral arrangement of muscle fibers that generate the peristalsis. Muscle fibers along the ureter terminate over the detrusor muscles of the bladder to form the trigone.[9] The muscularis layer gradually increases in thickness from the kidney to the bladder. Consequently, complete perforations occur at a higher frequency in the proximal ureter as compared to the distal ureter.[9][10] 

Autonomic input does not appear necessary for ureteral peristalsis. Instead, it is likely generated from intrinsic smooth muscle pacemaker sites in the calyces of the renal collecting system and propagated in an antegrade fashion. Sympathetic nerves transmit nociceptive signals generated from mucosal irritation, tension, or distension resulting in visceral-type pain, which may be referred to the flank, groin, or scrotal/labial regions. 

Lastly, a duplicated urinary collecting system is the most common urological congenital anomaly, occurring in approximately every 1 in 125 live births. Duplication of the ureters is bilateral in 20% of cases, frequently asymptomatic, and might be complete or incomplete. Duplicated ureters originate in a kidney pole. An incomplete duplication will terminate in the adjacent ipsilateral ureter, making a “Y shape” juncture at some point. Negotiating such a fork in the ureter with the ureteroscope entering only the selected renal unit can sometimes be challenging. This can be accomplished by using an angle tip guidewire to guide entry into the selected proximal ureteral segment.

A complete duplication will usually terminate in the bladder but can insert in various locations between the trigone and the ejaculatory duct in boys, or even in the vagina (where it can cause continuous, uncontrollable incontinence) in girls.[11] Only females can develope incontinence from the ectopic insertion of a duplicated ureter.  The distal insertion point of the duplicated ureter is a potential site for calculus obstruction. The challenge to visualize the orifice in the bladder of a duplex ureter may be overcome using various guidewires and/or intravenous agents that change the color of expelled urine. The proximal ureteral orifice (more lateral and cephalad) of a completely duplicated system typically drains the lower renal pole moiety and tends to reflux. The distal ureteral orifice (more medial and caudal) tends to obstruct and usually drains the upper pole renal moiety. This is known as the Weigert-Meyer law. 

Indications

Ureteroscopy has applications in diagnostic and therapeutic interventions. Generally, the rigid or semi-rigid ureteroscope is preferred for examination or intervention in the distal ureter, whereas the flexible ureteroscope can better maneuver the tortuosity of the upper ureter, renal pelvis, and calyces. Ureteroscopy approaches can be retrograde by urethral access or antegrade by percutaneous nephrostomy access.[12] Antegrade access is particularly valuable for patients with an ectopic ureteral orifice after ureteral reimplantation, renal transplant, ileal conduit, or neobladder. There is strong evidence that there is no significant permanent harm to the kidneys or renal function by ureteroscopy.[13][14]  Overall risk for ureteral stricture, for example, is only about 1%.

Indications for ureteroscopy include the diagnosis and treatment of:[15]

  • Filling defects observed in excretory CT urography (calculi, strictures, post-inflammatory changes, sloughed papilla, blood clots, fungus balls, ureteral and renal pelvic tumors)
  • Lateralizing essential hematuria (hemangiomas, minute venous rupture, varices, arterio-venous malformations, and neoplasms)
  • Foreign bodies (most commonly migrated or fragmented double-pigtail catheters and broken accessory devices)
  • Upper-tract neoplasms (including biopsy, surveillance, laser ablation, and palliative measures)
  • Fistulas (diagnostic modality of choice for definitive diagnosis of ureterovaginal fistula)

Ureteroscopy, in conjunction with endoluminal ultrasonography, can assist in identifying extraluminal causes of filling defects and further evaluate the intramural extension of malignant lesions.[16]

The most common indication for ureteroscopy is the management of renal and ureteral calculi. For nephrolithiasis patients with clinically significant stones in whom conservative or medical expulsive therapy has failed, surgical intervention is required. The American Urology Association Guidelines favors ureteroscopy over alternatives, such as shockwave lithotripsy (SWL) and percutaneous nephrolithotomy (PCNL), for treatment of calculi in the following instances:[17]

  • Mid or distal ureteral calculi, regardless of size (may also be used for proximal ureteral calculi, though SWL has similar efficacy and is considered the first-line therapy)
  • Suspected cystine or uric acid ureteral stones due to their radiolucency (uric acid) or resistance to SWL (cystine)
  • Renal calculi <20 mm in size (>20 mm, PCNL is generally preferred, but flexible ureteroscopy with laser lithotripsy is now a reasonable alternative except for stones in the lower pole.[18]
  • Removal of residual renal calculi fragments following SWL or PCNL including steinstrasse
  • Failure or anticipated failure of SWL, more likely in patients with large body habitus with a skin-to-stone distance of >10 cm
  • Patients who are not candidates for PCNL may be offered staged ureteroscopy with or without SWL (sometimes called "sandwich therapy")
  • Anatomic or functional obstruction distal to the calculi
  • Patients with uncorrected bleeding diathesis or who require continuous anticoagulation/antiplatelet therapy where SWL would be contraindicated

Though ureteroscopy is more invasive and has slightly higher morbidity than SWL, it has a more favorable stone-free rate.[17] It also appears to be fairly harmless to the kidneys with a minimal lasting effect on renal function.[13] 

A recent study of over 3,000 stone patients suggested that early intervention (ureteroscopy or SWL) should be considered in all stones >7 mm in size and in calculi 5-7 mm in the mid or proximal ureter.[19]

As the technology and design of equipment to perform ureteroscopy constantly evolves and improves, we can expect its indications to increase in the future.

Contraindications

Contraindications to ureteroscopy are few. Active urinary tract infection would require treatment and confirmed resolution before ureteroscopy. This typically involves placement of a percutaneous nephrostomy or a double-pigtail ureteral stent to establish urinary drainage on the affected side as well as the usage of appropriate antibiotics. Contraindication to general or spinal anesthesia would typically prohibit ureteroscopy. Bleeding diatheses or ongoing anticoagulant or antiplatelet therapy are relative contraindications and should be assessed on a case-by-case basis.[20] In general, ureteroscopy can usually be done safely in patients on anticoagulant therapy. 

Other contraindications would include ureteral kinking or narrowing (usually treatable with double-pigtail stenting) and impassable anatomy involving the ureteral orifice, prostate, trigone, or distal ureter due to cancer or other disorders. Flexible ureteroscopy is considered safe during pregnancy, unlike SWL, which is contraindicated, but thought should be given to anesthesia considerations and the possibility of early induction of labor.[21] The alternative is to use double J stents and percutaneous nephrostomy tubes but these necessitate very frequent changes in pregnancy, typically every 3-6 weeks, which require additional operating room procedures and more anesthesia.  

The single most important predictor of postoperative urinary tract infectious complications is the presence of a pre-operative urinary infection. Other risk factors include female gender, pre or postoperative stenting, diabetes mellitus, positive nitrites on pre-operative urinalysis, and longer operative length.[22][23] Ureteroscopy patients with larger stones (>13 mm) and a mid-ureteral stone location tended to have more post-op emergency room visits.[24]

Equipment

Modern ureteroscopes can be semi-rigid or flexible. The semi-rigid ureteroscopes are most useful for distal ureteral interventions. They are available in sizes of 7 to 12 Fr and have large, often dual, 3 to 6 Fr working channels for better irrigation and larger accessory instruments like baskets and lasers. Compared to the flexible instrument, the semi-rigid ureteroscope has the added benefits of lower cost, greater durability, larger and/or dual working channels, and easier maneuverability resulting in shorter operating times – an additional driver of reduced cost.[25] Semi-rigid and flexible ureteroscopes are generally available from 6 to 9 Fr, the smallest being for diagnostic purposes only. Flexible ureteroscopes now have digital video imaging and an angulation range at the tip of up to 275 degrees, compared to less than 10 degrees in the semi-rigid scopes. This allows flexible ureteroscopes to gain access to the renal pelvis and calyces through the kidney, including the lower pole, which presents the greatest tortuosity.

An important accessory to flexible ureteroscopy is ureteral access sheaths. These are available in sizes of 9 to 16 Fr and facilitate multiple passages of the ureteroscope into the ureter and kidney without the need for a guidewire or the risk of distal ureteral injury from repeated insertions. The benefits of the sheaths are two-fold: repetitive trauma to the distal ureter and ureteral meatus is avoided, and there is better drainage of irrigation fluid, enabling enhanced visualization and lower intraluminal pressures. There is a small risk that the sheath may cause ureteral wall ischemia, urothelial mucosal tears and subsequent strictures as well as ureteral and renal pelvic perforations; however, the placement of ureteral double pigtail stents in the post-operative period minimizes these risks to levels comparable to flexible ureteroscopy without access sheaths.[26][27]

Instruments that can be inserted through the working channel of the ureteroscope include wire baskets, biopsy forceps, balloon catheters, cold knife, and electrocautery. Instruments specifically designed for ureteroscopic lithotripsy include ultrasound, electrohydraulic and pneumatic probes as well as laser fibers. The ultrasound probe allows for continuous, simultaneous suction with stone ablation to reduce calculi retropulsion, but is considered the least effective option overall. Pneumatic probes may only be used through rigid and semi-rigid ureteroscopes and, while effective, they must be in direct contact with the stones to work. Laser fibers are the most versatile and have the smallest diameter (at less than 1 Fr). They come in several sizes but are generally from 200 to 360 microns (larger sizes are available for use in the bladder). Smaller laser fibers are more flexible and are usually preferred for use in the renal pelvis. Lasers, particularly the holmium:YAG laser, are highly effective for lithotripsy of all stone types as well as tissue ablation, coagulation, excision, incision, and vaporization.[5][28] 

The most significant advances in ureteroscopy over the last two decades related to the miniaturization of the scopes and accessories. A key development contributing to miniaturization is the evolution from fiberoptic to digital video optical systems. Unlike fiberoptics with direct-viewing lenses, the digital video optical system uses a charged coupled device (CCD) camera chip mounted to the tip of the ureteroscope and connected to a monitor display through a single cable. This achieves a higher quality image, is more durable and flexible than fiberoptic cables, as well as being thinner, allowing for a larger working channel. Future developments may see the addition of a second CCD camera chip to allow for three-dimensional imaging, as in robotic surgery.[5]

Another advance is the commercial introduction of disposable flexible ureteroscopes by several manufacturers. These allow for improved or at least new mechanics while avoiding wear and tear on the more valuable, reusable ureteroscopes. Optics are not yet equivalent to the standard, reusable, digital video ureteroscopes. They are ideal for emergencies where demand for ureteroscopes exceeds the available supply. They may even be cost-effective, as well.[29][30]

All of these advances have contributed to the development of ureteroscopes with multiple working channels. Dual working channels allow for simultaneous visualization, accessory function, and continuous irrigation. These advanced features were first developed in rigid and semi-rigid ureteroscopes, whose larger caliber channels allowed for additional functionality. Eventually, these features become incorporated into flexible scopes as well. Optical systems, accessories, and lasers continue to advance and become more compact; for example, there are now flexible dual-channel ureteroscopes under 10 Fr available commercially.

Personnel

The personnel required for ureteroscopy include the surgeon and an assistant (either a resident, scrub tech, nurse practitioner, or physician assistant) to help hold the wires, pass instruments and help operate the various baskets. When fluoroscopy with a radiological C-arm is necessary, a radiology technician is required as well.[31] (Dedicated cystoscopy tables may not require the presence of a radiology technician.) The operating room should also have anesthesia staff and a circulating nurse present.

Preparation

Planning is vital for a ureteroscopy to avoid unnecessary complications and minimize operating time. Imaging (such as a non-contrast CT and/or an abdominal x-ray (KUB) for urolithiasis) should be reviewed prior to the operation. Pre-operative urinalysis and urine cultures are critical so as to ensure there is no evidence of urinary tract infection (UTI). After obtaining informed consent, the patient should be anesthetized then properly prepped and draped, typically in the dorsal lithotomy position utilizing stirrups, with accurate side marking and prophylactic antibiotics according to AUA guidelines.[32][33][34] Prior meta-analyses have shown that prophylactic antibiotic administration was not associated with a reduced risk of postoperative febrile UTIs but did provide a lower risk of post-operative pyuria and bacteriuria.[35][36]

Advise patients preoperatively that a two-stage procedure may be necessary if ureteral narrowing, excessive bleeding, or other technical problems are encountered and a double J stent had to be placed. This way, they are not suddenly surprised to find out after surgery that another procedure will be required.  Such procedures are optimally scheduled about two weeks later. 

The 2019 AUA guidelines for antibiotic prophylaxis recommend tailoring the prophylactic agent towards the individual patient (based on prior urine culture results, the hospital’s antibiogram, and any additional risk factors the patient may have). The choice of antimicrobial would preferably be a single dose of a first or second-generation cephalosporin or trimethoprim-sulfamethoxazole (TMP-SMX).[34] Alternatively. a combination of ampicillin and gentamicin or amoxicillin/clavulanate can be used.

If a parenteral antibiotic is chosen, it must be administered within one hour prior to the introduction of the cystoscope so that an appropriate peri-operative tissue concentration is established. If an oral agent is chosen (such as TMP-SMX or amoxicillin/clavulanate), certain factors must be taken into account such as the variable amount of time to reach adequate tissue levels and that patients may be under a “nothing by mouth” dietary restriction prior to the procedure. For these reasons, an intravenous agent may be preferred.  A single dose of gentamicin used preoperatively, in addition to the standard prophylactic antibiotics, may be useful in controlling postoperative infections when performing procedures on infected systems or in patients deemed highly susceptible to infection.[37][38] (Gentamicin is absorbed well into renal tissue and provides additional, long lasting renal antibiotic prophylaxis even from a single preoperative dose.  We typically use a dosing of 3 mg/kg body weight.)

Although general anesthesia is recommended, combined spinal-epidural anesthesia has been shown to be an adequate alternative [39]. However, the urologist might prefer or even require the patient to be under full general anesthesia as there is less patient movement which is particularly important for semi-rigid ureteroscopy[40]. Also make sure the operating table is able to handle the patient's weight, especially when the patient is moved to the extreme end of the table for cystoscopy in the dorsal lithotomy position. Prior to starting the case, all equipment and supplies (mentioned earlier) should be prepped and readily available including a selection of guide wires, baskets, laser fibers, connectors, double-pigtail stents, dual lumen catheters, high-pressure irrigation system, retrograde catheters, diluted contrast, a torque vise, an Albarran bridge, urethral mechanical and balloon dilators as well as other appropriate supplies based on the individual case, as this is ultimately the surgeon's responsibility.

If a dedicated cystoscopy fluoroscopy table and suite is not available, try to position the ureteroscopic video tower on the side of the patient's stone and the C-arm (x-ray) on the opposite (contralateral) side.  We have found that often the optimal arrangement is to have the C-arm monitor more cephalad (closer to the patient's head) but on the same side as the C-arm. Viewing of the C-arm monitor is then achieved by looking through the vacant, open center arc of the C-arm.

Technique

Cystoscopy is necessary prior to any ureteroscopy to better understand the patient's individual anatomy, visualize the bladder and ureteric orifice, perform retrograde pyelography, and place the initial guidewire.[31][32] With a male patient, the penis should initially be held vertical to keep the pendulous urethra straight to facilitate the insertion of the cystoscope. The cystoscope tip is then angled upwards (anteriorly) in the deep bulbous urethra, under vision, to enter and pass through the external sphincter, prostatic urethra, and bladder neck to enter the urinary bladder. With the cystoscope in the bladder, a complete visual examination of the bladder should be done. A scout x-ray film or non-contrast image is obtained. Next, a small ureteral catheter is flushed, to remove any air bubbles, and inserted into the ureteral orifice through the cystoscope.

If having trouble negotiating the ureteral orifice, use an angled tip, stiff hydrophilic guidewire through an open-ended catheter (which helps stabilize the wire).  Place the cystoscope tip as close as possible to the ureteral orifice to avoid bowing of the guidewire.  A torque vise attached to the distal end of the wire can help control the guidewire while gently twisting and advancing.  An Albarran bridge can help cannulate an awkwardly oriented ureteral orifice. Sometimes, changing the orientation of the cystoscope by 90-180 degrees will assist the entry and passage of the guidewire. A retrograde pyelogram using a cone tip ureteral catheter can help visualize the distal ureter where entry through the ureteral orifice is difficult. If all the above fails, try positioning a semi-rigid ureteroscope directly at the ureteral orifice; then try passing the guidewire through the scope. A retrograde pyelogram can also be performed in the same manner.[41]

A small volume, typically around 3 cc's, of diluted fluoroscopic contrast (usually 50/50) is gently injected into the distal ureter via the ureteric catheter for a retrograde ureteropyelogram to visualize the ureteral anatomy and identify the size, shape and exact location of any stones. Next, a safety guidewire is placed through the ureteral catheter into the renal pelvis.[42] If there is cloudy or purulent urine draining from the ureter or renal pelvis prior to ureteroscope placement, this is a presumptive sign of infection even if the pre-operative urinalysis was negative. A urine culture should be done of the abnormal urine and ureteroscopy should be postponed. A double-pigtail stent should be immediately placed.  Ureteroscopy should be rescheduled for a later date after a full course of appropriate antibiotics and subsequent negative urine culture. If the urine is clear, the procedure may continue.

The bladder should be drained prior to inserting the ureteroscope. This helps advance the scope through the orifice without undue intramural ureteral compression.[31][42] A second "working" guidewire may be utilized to navigate and "railroad" the ureteroscope through the ureter. Care should be used in advancing the ureteroscope as the wire coating can sometimes be stripped and result in a nidus for future stone development. This second wire can be placed either through the cystoscope alongside the previous wire or after removal of the cystoscope via a dual lumen catheter.

There are several advantages to using the dual lumen catheter. A retrograde pyelogram can be done through the second channel for better visualization. Just passing the dual lumen catheter can act as a ureteral dilator. Since it has a relatively large lumen, lidocaine jelly can also be injected to help reduce spasm. If the dual lumen catheter has trouble entering or advancing in the ureter, this is an indication of ureteral narrowing. In such cases, it is prudent and advisible to just leave a double J stent for a few weeks to allow for passive ureteral dilation and return a few weeks later to complete the ureteroscopy. At the very least, a smaller caliber ureteral access sheath should be used but the likelihood of intimal ureteral injury and scarring is increased. 

The handle of the ureteroscope should be held with the dominant hand while the scope is advanced with the non-dominant hand. The scope may be slowly and easily advanced (with the distal tip kept straight) into the renal pelvis. The use of pressurized irrigation (normal saline is preferred due to the reduced risk of tissue damage if the fluid is absorbed or extravasates) will assist in dilating the more proximal ureter and filling the renal pelvis to allow for better visualization.

Although there are several diagnostic and therapeutic indications for ureteroscopy (as mentioned above), the procedure is most commonly used for the management of ureteric or renal stones. The choice of either semi-rigid or flexible ureteroscopy comes into play at this point as several factors must be weighed: stone location, size, and shape, cost, availability of equipment as well as the individual surgeon's preference and experience.[31] For example, lower pole calculi are likely to necessitate a flexible ureteroscope.

Ureteral Access Sheaths

A ureteral access sheath may be inserted over the "working" guidewire (to the point of the stone location or ureteropelvic junction depending on the patient's clinical presentation) to allow for repeated ureteroscope passage.[32] The dilator portion of the ureteroscopic sheath can be inserted over the guidewire first or the dual lumen catheter can be used as an initial ureteral dilator.  If either or both of these encounters significant resistance, a smaller sheath should be considered or the ureteroscopic procedure can be postponed with immediate placement of a double-pigtail stent. This will gently dilate the ureter over the next several weeks at which time the ureteroscopy can proceed much more easily and without the risk of significant ureteral damage from overly aggressive or forced dilation.[43] The smallest diameter sheath that will comfortably fit and be adequate for the job should be used.  When dealing with multiple and bigger stones, a larger diameter sheath is helpful, if safe placement is possible.  It is important to know where the stone is located so the ureteral access sheath is not advanced beyond that point as this can push the calculus through the wall of the ureter.

It is important not to forcefully advance the ureteroscopic sheath, its dilator, or the dual lumen catheter if there is considerable ureteral resistance. The dilator and sheath should be carefully advanced only to the level at which the ureteroscopy is expected to be performed.  It is very easy to advance the sheath or dilators too far and risk mucosal injury, ureteral disruption, or renal pelvic perforation, so we recommend only advancing an inch at a time with full fluoroscopic guidance when the tip of the sheath or dilator approaches its expected final position. Despite these risks and cautions, we generally recommend the use of two guidewires (one "working" and one a "safety" guidewire) as well as ureteroscopic access sheaths.  Overall, the use of ureteral access sheaths is safe and does not appear to substantially increase the risk of ureteral strictures compared to ureteroscopy without sheaths.[44]

Up to 20% of patients undergoing ureteroscopy will have narrow ureters that require substantial effort to dilate sufficiently to pass a ureteral access sheath.[45] A retrograde pyelogram can indicate the relative diameter of the ureter.  A dual lumen catheter is often used for a retrograde pyelogram and to place a second guide wire. If the dual lumen catheter does not pass easily, this almost certainly means the ureteral lumen is too narrow for a ureteral access sheath and consideration should be given to leaving a double J stent and rescheduling the surgery for a later date.  When choosing a ureteral access sheath, the smallest feasible diameter should be used to minimize ureteral trauma.

Using an access sheath is optional as it has both pros and cons. The main benefit is to facilitate repeated introductions of the ureteroscope into the ureter and renal pelvis.  The main disadvantage is that placement is not always easy as it can easily cause ureteral intimal tearing, hematuria and even ureteral perforation.  Further, it is highly advisible to use a double J stent whenever a ureteroscopic sheath is used unless the ureter has been previously stented.

When the decision is made to use a ureteral access sheath, the correct lengths are as follows:

  • Use a 35 to 36 cm long ureteral access sheath or shorter for all semi-rigid ureteroscopy (male and female) and for flexible ureteroscopy in female patients. 
  • In males, use a 45 to 46 cm length ureteral access sheath for flexible ureteroscopy.

Semi-rigid Ureteroscopy

Semi-rigid ureteroscopy is typically reserved for the distal ureter which avoids the angulation necessary to advance into the mid and upper ureters.  While semi-rigid scopes can be advanced further, as a general rule a flexible ureteroscope is preferred in these situations.  When using a semi-rigid scope, it is prudent to remember that this is an inflexible, sharp ended instrument that can easily cause considerable damage if not handled properly.  It can be advanced into the bladder by itself, over a guidewire, through a short ureteral access sheath or even a through an empty cystoscope sheath but using sheaths limits the potential proximal advancement of the scope.  Consider advancing the ureteroscope over a guidewire to minimize urethral trauma in complicated urethras. Careful adjustment of the irrigation fluid flow can help advance the scope, but it may also push the stone retrograde and out of reach if not reduced and adjusted appropriately. We prefer to dilate at least the intramural portion of the ureter with the dilator portion of a ureteral access sheath or a dual lumen catheter to help facilitate initial entry of semi-rigid ureteroscopes. Stones removed without an access sheath can be deposited in the urinary bladder to facilitate the re-introduction of the ureteroscope into the ureter without the need to remove it completely from the bladder each time.[12] 

When advancing the ureteroscope, the ureteral mucosa should appear to pass the scope. If there is much resistance and the mucosa is not moving, avoid using excessive force.  Instead, gently pull back on the scope and retry advancing.  If there is obvious mucosal damage or injury, it is prudent to remove the ureteroscope and leave a double-pigtail stent.  The ureteroscopy can be rescheduled for a later date (usually around two weeks).[41] Remember when advancing semi-rigid ureteroscopes that the ureter is not straight.  If the ureter develops spasms and hugs the scope, be particularly slow and cautious when withdrawing.  If no safety guidewire is present, it may be prudent to have a wire pre-loaded in the scope in case of passed stones or significant mucosal injury is found on examination during withdrawal.

Flexible Ureteroscopy

Once the ureteroscope is inserted into the renal pelvis, the "working" guidewire, which helped to “navigate” the ureter, should be removed. This leaves a second "safety" guidewire in place. The distal end of the "safety" guidewire should be secured in its holder or by clamping it to the drapes in such a way that it will not interfere with completing the ureteroscopy. A small basket (such as a zero-tip basket) or a small laser fiber may then be placed within the “working channel” of the ureteroscope.[32] Normal saline irrigation, either with a pressure bag at 300 lbs pressure or a hand-operated pressure syringe, should be attached to the ureteroscope. In rigid ureteroscopy where there is often a dual-channel, the irrigation is attached to the smaller port. 

If there is only a single channel, then a dual-channel adapter should be used such as a Tuohy-Borst Y adaptor.  This allows the irrigation to be attached to the channel using the offset port leaving the adjustable diaphragmatic port available for the basket, laser fiber, or guidewire.  In general, there was no significant difference in complication rate between the use of a continuous high-pressure irrigation bag vs. a hand-operated pressure syringe, although there were slightly fewer complications with the pressure bag, most likely from the avoidance of overly high irrigation pressures.[46] Use the safety guidewire as a guide to help with orientation when inspecting the renal pelvis. A quick fluoroscopic image of the ureteroscope in each calyx will help verify a complete inspection as well as facilitate re-entry to a specific calyx.

In longer cases, the lubricious coating to the lumen of the ureteral access sheath may become worn.  To minimize this, adding a little lubricant to the scope each time it is removed prior to its reinsertion, will help maintain the easy passage of the ureteroscope through the sheath's lumen.

Lasers

For stone fragmentation, the laser can be set to initial settings of 5 to 10 Hz frequency with 5 to 9 Watts of power.[47] For ureteral stones and for stone vaporization, lower power settings with a higher frequency is recommended, such as a power level of 0.2 with a frequency of 25 to 50 Hz.  Some lasers are able to use dual settings so the surgeon can quickly go from one power setup to the other.  Of course, individual lasers will require different settings, but the principle is the same: higher power and slower frequency tend to promote stone fragmentation while lower power with higher frequency settings will optimize vaporization and tend to minimize stone migration.[48][49][50][51] 

Unlike stone fragmentation, laser vaporization is best accomplished without having the laser fiber in direct contact with the target.  It is only necessary to closely approach the stone with the laser fiber to vaporize it.  The main issue with laser stone vaporization is that it takes more time and it may limit the stone material available for chemical analysis. In some cases, there will be a harder, more resistant central stone at the core that may be best managed by fragmentation and stone basket extraction rather than vaporization.

A combination of vaporization and fragmentation techniques may also be used.

Once the stone is visualized, the surgeon can begin to fragment it into basketable sized pieces. The pieces can then be captured with a stone basket and removed along with the ureteroscope through the ureteral access sheath.  If the stone fragment is too large to enter the access sheath, it can be repositioned inside the basket by pushing it back into the dilated proximal ureter or renal pelvis; then carefully opening and closing the basket slowly to allow the stone to reorient in a more favorable, longitudinal position. Repeat lasering of the stone can also be done until it is small enough to fit through the access sheath. 

It is possible to laser a stone already in a basket if the stone is engaged but too large to extract.  Open the basket and use a small laser fiber to break up or vaporize the stone until it is small enough to extract. Avoid lasering the wires of the basket.

Another technique involves pulling the stone as much as possible into the proximal end of the ureteral access sheath and then removing the sheath, ureteroscope, basket, and stone all together while keeping traction on the stone basket. This allows the access sheath to act as a dilator or leader and facilitate the stone's removal, but there is a real risk that the stone may still get stuck.  Therefore, it should only be done when the stone is close in size to the diameter of the access sheath.  Also, the ureteral access sheath will have to be replaced after extraction of the stone with the sheath which takes additional time.  This is a relatively risky maneuver which becomes more dangerous the more proximal the stone's location.  It should generally not be done for larger or borderline calculi in the renal pelvis.  In such cases, additional lasering of the stone is preferred. (If this maneuver fails and the stone gets stuck, overly aggressive pulling on the stone, sheath or ureteroscope should be avoided.  Instead, disengage the stone by releasing it from the basket and use laser lithotripsy to reduce its size so it will fit through the access sheath.) There is also the risk of getting a piece of the ureter jammed between the stone and the sheath which would cause a rent, perforation or could even disrupt the ureter completely.  Therefore, this technique is not recommended as a routine practice and only by experienced practitioners.

The dual lumen catheter is the ideal tool to replace the second guidewire (assuming the "safety" guidewire is still in place) which allows the ureteral access sheath to be easily replaced. The ureteral access sheath should never be advanced without the dilator in place and only over a guidewire.  The inner dilator should never be placed or advanced except over a guide wire due to the very significant risk of a perforation of the ureter or renal pelvis. All stone fragments removed should be sent for chemical analysis.[52]

Once all the stones have been removed, the ureteroscope and ureteral access sheath may be slowly extracted together, to inspect the ureter for any passed stones as well as for any intimal or mucosal injury.[32][42] An alternative technique involves replacing the guide wire ghtough the scope, then withdrawing the access sheath until the end is at the scope's handle.  Then the ureteroscope can be slowly withdrawn to inspect the ureter while still leaving a wire in place. This technique is somewhat easier and particularly useful if the operator is alone or working with inexperienced or unskilled help. The finding of any significant ureteral mucosal or intimal damage should suggest the need to leave a double-pigtail stent, typically for 2-4 weeks.  Cases where the stones are easily removed and there is minimal resistance to ureteral dilation or access sheath placement, as well as those patients who had a double-pigtail stent immediately before ureteroscopy, may not need to have a stent placed after the procedure.[53]  If a bilateral procedure is done, at least one side should be stented.  If in doubt about leaving a stent or not, it is always safer to leave the stent.  Our policy is to always leave a sdouble-pigtail tent if a ureteral access sheath was used unless the ureter was pre-stented. 

Lastly, a double-pigtail ureteral stent may be placed over the remaining "safety" guidewire and inspected for good curl both within the renal pelvis and distally in the bladder. This decision is up to the individual surgeon but is strongly recommended for patients with ureteral damage on ureteroscopic inspection and those with an increased risk of bleeding, perforation, urinary tract infections, or significant residual fragments.[33] The recommended technique for double-pigtail stent placement is well prescribed elsewhere, but we will summarize some of its suggestions.[52]

It is recommended that the dangler thread NOT be removed until after the stent is in an optimal position as it allows for easy removal if an exchange is desired and stabilizes placement. Stiffer guidewires make placement easier but are also more likely to cause a perforation so they should be placed more carefully. Measuring the ureteral length with an appropriately marked ureteral catheter is a far more reliable way to select a double-pigtail stent length than relying just on patient height alone. Use a stiffer stent if bypassing a stone as it better resists compression and it will often have a tighter curl for the renal pelvis.  Do NOT leave a dangler thread for any stent that is critical.  Placement is optimized by pulling the guidewire back enough to allow the tip of the stent to curl while maintaining traction on the dangler thread and the pusher.  This can be moved into and out of the ureteral orifice slightly to allow the tip of the stent to curl properly.[52]

Once the guidewire has been removed and all aspects of the genitourinary tract have been inspected for any iatrogenic injury, the patient may be safely extubated and transferred to the post-operative care unit. The ureteral stent can be left with or without a dangler thread. If the dangler thread is left on the stent, the stent can be easily removed at the bedside, in the clinic or even by the patient themselves at home. If the thread is removed, flexible cystoscopy will be required to extract the stent with a flexible grasper. Stents are usually removed between 3 to 7 days postoperatively after successful ureteroscopy. After the stent is removed, follow-up ultrasound or an x-ray (KUB) should be performed between 4 and 6 weeks later to rule out any residual fragments or silent hydronephrosis. 

American Urological Association Guidelines on stones recommends that all patients who have had ureteroscopic stone surgery should be informed about the potential benefits and availability of 24-hour urine testing and prophylactic medical therapy for nephrolithiasis.[54] Interpretation of such 24-hour urine tests has become much easier and is now routinely done by many urologists, nephrologists, and primary care physicians using published guides.[55]

Bilateral ureteroscopic procedures can be done with good success rates and only slightly higher complication rates.  Individual patient circumstances should be considered as well as the extra anesthesia time necessary.[56][57]

"Tricks of the Trade" [31][41][42][58][59]

  • Some experts recommend doing a semi-rigid ureteroscopy immediately prior to all flexible ureteroscopies for distal ureteral inspection and dilation.  It will also help identify any stones that have unepectantly relocated to the distal ureter.
  • Every ureteroscopy is different and unique.  Do not assume that any ureteroscopy will be "routine" as this can lead to unintended consequences.
  • Have a wide variety of stents, guidewires, connectors, clamps, baskets, and scopes available.
  • It is recommended to have a "safety" guidewire in place in the renal pelvis for access in case of unexpected difficulty.  Secure it carefully so it isn't accidentally lost, pulled or removed.
  • Be aware of the skills and experience of your assistants.  It can be very disconcerting when your assistant accidentally removes your safety wire, cuts the dangler or opens instead of closing the basket. Review procedures with your assistants before starting the surgery.
  • Stiffer guidewires can help make ureteral access sheath placement and double-pigtail stent advancement easier.  They are also less likely to buckle but may increase the risk of perforation so place them with extra care.
  • The dual lumen catheter is an extremely important accessory.  It can be used as a ureteral dilator, a stone pusher, to inject diluted contrast for retrogrades, to place a second guide wire or to replace a guide wire. 
  • If one guidewire type cannot bypass a stricture, impacted stone, or other blockages, try a different type of guidewire. Hydrophillic wires generally work best for this.
  • When doing retrograde pyelograms, mixing diluted contrast with lidocaine jelly or plain lubricant will increase its viscosity while keeping its radio-opacity and help keep the contrast in the renal pelvis longer, if that is desired.  Stir the two together slowly and carefully to avoid air bubbles.
  • If ureteral strictures are found, it is better to leave a double-pigtail stent for a few weeks rather than use mechanical or balloon ureteral dilators.
  • To minimize radiation exposure, the use of static, pulsed X-ray pictures is recommended instead of live, continuous exposures.  Use of the "Last image hold" feature is also recommended. 
  • Always use the minimum amount of radiation exposure necessary.
  • Always take a scout film before injecting any contrast. (Stones move and it serves as a good reference.)
  • Remember to flush the ureteral catheters to eliminate air bubbles.
  • Never do "blind basketing".
  • It is recommended that the dangler thread on double-pigtail stents not be cut or removed until the stent is in its final position.  Once the thread is cut, further positional adjustment as well as replacement is much more difficult.
  • Never vigorously pull, push or twist any instrument in the ureter or renal pelvis.  It may not be possible to repair the damage later.
  • Avoid aspiration through the ureteroscope as it will cause more bleeding. 
  • If it becomes difficult to see clearly due to bleeding, use the high pressure irrigation flow and just be patient.
  • If the stone size has been misjudged when basketing, do not hesitate to use the laser to fragment or vaporize it. 
  • A laser should always be available when doing ureteroscopy for urinary stones.
  • Don't waste time basketing very tiny stones.  Anything smaller than the shaft of the basket or guidewire can probably be left behind.  However, in the case of infectious stones, try to basket and remove everything you can.
  • If contrast bypasses an obstructing stone, it should be possible to pass a guidewire beyond it.
  • Very distal stones may not require initial retrograde pyelography that can inadvertently push stones further proximal.
  • Impacted stones can sometimes be gently nudged proximally by a catheter or the tip of the ureteroscope, but this must be done carefully.  If unsuccessful, limited laser lithotripsy can be done but only sufficiently to place a guidewire.
  • Be particularly careful when advancing the ureteral access sheath as it can easily damage the ureter or renal pelvis.  It can easily progress more proximal further than expected unless its position is carefully monitored.  Use fluoroscopy for optimal positioning,  never advance the ureteral access sheath without the dilator inserted and only with a guide wire in place.
  • Be familiar with all the controls on the ureteroscope and use them. Most flexible ureteroscopes will flex the tip upwards and down when the calices and stones are generally left or right. Reusable scopes typically have an adjustment so the shaft can be rotated 90 degrees right or left to facilitate caliceal examination and entry.  Disposable ureteroscopes usually lack this adjustment and will need to be rotated more by hand to the left or right as needed which can be somewhat awkward. 
  • High-pressure irrigation is one of your most important and useful tools. High flow rates will promote visualization, ureteroscope advancement and ureteral dilation, but may also push the stone proximally.  High pressure can also cause a calyceal rupture and promote bacteremia. In the renal pelvis, too much flow can cause the stone to jump around and move from one calyx to another. Therefore, in the kidney, use the minimal amount of irrigation flow necessary for visualization.  You can also briefly use higher irrigation flow rates to jiggle a stone around so it can be captured by the stone basket.
  • Lasering of stones creates a dust cloud.  To maintain visibility, use the irrigation at the lowest flow rate sufficient to maintain vision. 
  • Most stone baskets will retract (move closer to the ureteroscope) when being closed.  To avoid this, advance the stone basket at the same rate as the assistant is closing it.  This will close the basket around the stone without retracting the basket.
  • No matter how bad the ureter looks after ureteroscopy, it will almost certainly heal just by leaving a double-pigtail stent and waiting sufficient time; usually 4-6 weeks.  A follow-up ultrasound is recommended in such cases to identify "silent" hydronephrosis.
  • Always discuss the availability of 24-hour urine testing for stone prophylaxis with the patient and document this in the medical record.
  • Keep track of all double-pigtail stented patients as the urologist is responsible for their removal even if the patient does not return for their post-operative visit.

Surgeons are reminded of the immortal words attributed to famed endourologist, Dr. Arthur Smith, who said: "When the going gets tough, the tough leave a double-J stent and go home!" Nothing is as bad as having to deal with a serious, avoidable complication such as a complete ureteral avulsion from the renal pelvis. Experienced surgeons will not hesitate to leave a double-pigtail stent and return another day to finish a ureteroscopy in which they encounter difficulty with ureteral narrowing, visualization, infection, bleeding, or other significant difficulties. This is good advice for all who perform ureteroscopy. 

Complications

Ureteroscopy has evolved in the past few decades with the advent of new scopes and various accessories to help increase the safety of the procedure. However, complications, both minor and severe, still exist. Minor complications include hematuria, mild urinary tract infection, double-pigtail stent discomfort and transient creatinine elevation. More severe complications, though rare, include severe urosepsis, extra-ureteral or submucosal stone migration, ureteral perforation, ureteral stricture, and ureteral avulsion.[60][61][62]

Clinical Significance

Ureteroscopy has been a revolutionary tool within the armamentarium of the endourologist. It is an effective, safe, outpatient, minimally invasive technique for both diagnostic and therapeutic purposes. However, this procedure requires proper training and care to prevent avoidable complications. The rapid design of newer, more advanced scopes and ancillary equipment will give greater access to treat even more complex cases in the future.[31][32]

Enhancing Healthcare Team Outcomes

Ureteroscopy is best performed by an experienced team. Proper ureteroscopy takes time for patient positioning, instruments and accessories to be used.  The radiology tech and surgeon should communicate clearly about the use of live or static images as well as how to move the fields and which terms to use.  The initial strategy and plan should be discussed with staff immediately before starting the procedure so all personnel involved understanding what is being done. Close cooperation between the surgical assistants, nursing staff, and surgeon ensures better outcomes and more efficient, safer ureteroscopies. 


Article Details

Article Author

Shaun Wason

Article Author

Sina Monfared

Article Author

Annaliese Ionson

Article Editor:

Stephen Leslie

Updated:

2/10/2021 3:56:32 PM

PubMed Link:

Ureteroscopy

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