Marshall L. Stoller, Maxwell V. Meng-Urinary Stone Disease

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598 El-Hakim, Tan, and Smith

guidewire and under fluoroscopic guidance. During either flexible or rigid uretero-

scopy, the bladder should not be overdistended and pressure in the upper tract should

be kept to a minimum. A retrograde pyelogram is performed to outline the upper-tract

collecting system anatomy, and the flexible ureteroscope is advanced under both direct

vision and fluoroscopic guidance into all minor and major calices to map the entire

system. When instruments are introduced, the tip of the scope must be straightened to

avoid damage to its internal sheath. Access to the lower calyx can be challenging if the

infundibulopelvic angle is acute, the lower calyx infundibulum is long and the intrarenal

collecting system is dilated. Once positioned in the renal pelvis, the combination of

maximal active deflection and advancement of the flexible endoscope causes buckling

of the secondary-deflecting segment. This maneuver directs the tip of the instrument

near the lower pole infundibulum, and by reversing the active deflection and continuing

to advance the endoscope, the lower pole calyceal system can be entered. Secondary

deflection is required in approx 60% of lower calyceal access. In the remaining cases

active deflection alone is sufficient and the tip is deflected toward the lower pole infun-

dibulum as soon as the ureteroscope passes the ureteropelvic junction. Alternatively, the

ureteroscope is deflected in the renal pelvis and then withdrawn into the lower calyx.

A guidewire can be directed and coiled in the lower calyx and then the scope advanced

over the wire. Prone positioning of the patient with the head down 20° has been shown

to provide the broadest angle of entry to the lower pole infundibulum (21). Lower pole

stones can be treated in situ or moved, with flexible 2.5 Fr graspers or a basket, into a

position that allows better visualization. Use of a head-down position with the ipsilateral

flank elevated may help the stone or fragments to migrate cephalad and become more

accessible.

Great care must be taken in handling and sterilizing these delicate instruments. One

study showed that flexible ureteroscopes were used for an average of 3–13 h before they

needed repair. The most fragile part of these instruments was the deflection unit (22).

Fig. 6. The DUR-8 Elite flexible ureteroscope from ACMI has a second lever to control an

additional point of deflection located more proximally on the shaft.

Chapter 30 / Ureteroscopy 599

RESECTOSCOPE

Ureteroresectoscopes incorporate working elements much like standard resecto-

scopes. The tip of these resectoscopes can be insulated to permit use of electrocautery.

Working elements include resecting loops, cold and hot knife blades, and fulgurating

electrodes. A ureteral resectoscope is used in a similar fashion to a standard resecto-

scope. However, the former carries the disadvantage of having a smaller diameter. The

working space is also limited within the ureter lumen. It can be used to obtain tissue for

pathologic evaluation of a suspicious upper urinary tract lesion as well as to treat known

upper tract transitional cell carcinoma. Deep resection of the ureter is avoided to pre-

vent deep thermal injury to the ureteral wall and ureteral perforation. The base of the

lesion and the surrounding areas can be fulgurated with electrocautery using the resec-

toscope loop. Placement of a ureteral stent is recommended after completion of the

resection.

Wires

Guidewires secure the ureteral lumen and serve as guidance to introduce various

instruments and working tools. Different types of guidewires are available, each designed

with particular properties to help accomplish specific tasks. In most ureteroscopies, a

standard 145 to 150 cm long, 0.035 or 0.038 in., polytetrafluoroethylene (PTFE)–coated

guidewire can be used to secure ureteral access.

Guidewire diameter range from 0.018 in. (0.46 mm) to 0.045 in. (1.15 mm). Available

lengths vary from 80 to 260 cm. The distal 3–8 cm of most guidewires are designed to

be soft and flexible to minimize trauma. Bentson and Newton wires have longer flexible

tips up to 15 cm. Guidewire tips are either straight, angled, or have a “J” configuration.

Some wires have floppy tips at both end, which facilitates flexible ureteroscope back

loading and also minimizes damage to the internal endoscopic channel.

The basic design of a guidewire consists of a solid stainless steel core around which

is wrapped a coiled spring wire. The outer surface of the spring wire can be coated with

various materials to decrease friction between the wire and the instruments passed over

it. These coatings include PTFE, Teflon, and different types of hydrophilic polymers.

Several guidewire manufacturers have developed hydrophilic polymer coatings with

minimal friction and very slippery and flexible qualities. These properties are helpful to

negotiate a ureteral kink or bypass an impacted stone. It is essential that the hydrophilic

guidewire be wet with water or saline to activate the surface polymer. The core part

provides rigidity to the guidewire and can be either fixed or moveable. If moveable, the

core part can be withdrawn longitudinally from the outer spring wire, thus varying the

flexibility and rigidity of the guidewire tip. By increasing the diameter of the solid core,

the guidewire stiffness can be increased as well. Amplatz Super Stiff wires (Boston

Scientific, Microvasive) are constructed with a larger flat core component, which pro-

vides resistance to buckling or kinking owing to greater intrinsic rigidity.

Baskets

Baskets are available in different sizes and designs. The main components are the

handle, the control wire, the sheath and the basket itself. The basket is opened by advanc-

ing the control wire out of the sheath and closed by pulling it back into the sheath. Baskets

differ in their design (shape, number of wires, tip configuration), material, handle type,

sheath diameter (2.0–7.0 Fr), and working length. Helical and nonhelical designs (spheri-

600 El-Hakim, Tan, and Smith

cal and elliptical and so on) are available, with three or more wires. Double-wire designs

can add strength and may ease opening of the ureteral lumen. The tip is a small extension

at the distal end of the basket where wires reassemble. Tipless or 0-tip baskets are now

available; their main advantage is to reduce the likelihood of mucosal damage and

perforation. Filiform tips (up to 15 cm) projecting beyond the basket are available in

some designs. Filiform-tipped baskets can be helpful for passing the basket beyond the

stone ureteroscopically and to re-advance it easily if the stone is not engaged in the open

basket.

The material used to build a basket influences its strength, malleability and memory.

Nitinol alloy (nickel-titanium) provides for some of these characteristics. The nitinol

wire memory allows the basket to retain its shape after extreme torsion. The wire shape

alters characteristics of the basket. Most baskets possess cylindrical wires, but flat-wire

and delta wire designs are also available. Flat-wire baskets can be used for ureteroscopic

biopsy and excision of papillary tumors on a stalk. The Segura basket, which is a flat

wire basket, cannot be rotated because it can damage the ureteral mucosa. Delta-wire

design offer a larger surface section of each wire within the cylindrical sheath; thus, the

overall strength can be increased for the same sheath size, or alternatively, a smaller

sheath diameter becomes possible for the same basket strength. Basket modification

with a central channel is also available for laser fiber lithotripsy, in case of stone entrap-

ment.

Lithotrites

Small ureteral stones can be extracted intact during ureteroscopy; however, larger

stones require fragmentation. Intracorporeal ureteral lithotripsy presents different chal-

lenges from lithotripsy during percutaneous nephrolithotomy owing to anatomical and

technical considerations. Four ureteral lithotrites are available, namely, electrohydraulic

(EHL), pneumatic (ballistic), ultrasonic, and laser lithotripsy. Laser and EHL are flex-

ible lithotrites, whereas pneumatic and ultrasonic are rigid lithotrites.

LECTROHYDRAULIC LITHOTRITES

The first report of ureteral lithotripsy with EHL using a rigid ureteroscope was in 1985

(23). The use of smaller EHL probes through flexible ureteroscopes started in 1988 (24).

EHL produces an electrical spark, which generates a shock wave within a liquid envi-

ronment that fragments the stone (25). Flexible probes range in diameter from 1.6 to 5

Fr. There is little difference in fragmentation ability among the different probes, but use

of smaller probes is beneficial because irrigation is improved. However, larger probes

have enhanced durability (26). EHL works efficiently in normal saline, eliminating the

risk of hyponatremia with sterile water (27).

Unfortunately, EHL has a narrow margin of safety owing to the risk of damage to the

ureteral mucosa, and ureteral perforation. Despite technological advancement, ureteral

perforation remains an issue of concern with reported rates of 0 (28) to 39% (29).

Perforation may occur even when the probe is not in direct contact with the ureteral wall,

and the risk is proportional to the energy used (25). The risk of perforation may be higher

for impacted stones especially when vision is impaired by minor bleeding commonly

encountered during EHL (30). Compared to Holmium:YAG lithotripsy, retropulsion of

calculi occurs more frequently with EHL, and stone fragments are larger requiring

repeated basketing (31).

Chapter 30 / Ureteroscopy 601

EHL successfully fragments 90–98% of stones but the 3-mo stone-free rate is lower

because some large fragments may be retained (28,29). Stone-free rates decrease with

ureteral stones larger than 15 mm (67%) and are significantly lower than those seen with

Holmium:YAG lithotripsy (100%) (31).

The flexible nature of EHL probes is the major advantage of this lithotrite. It allows

intracorporeal lithotripsy throughout the entire upper urinary tract with both rigid and

flexible ureteroscopes. In addition, EHL is the least expensive intracorporeal device. On

average 1–1.3 probes are used for each procedure, except with harder stones (28).

The small 1.6 and 1.9 Fr probes must be used for ureteral lithotripsy. The probe is

positioned about 1 mm from the stone surface and should be extended at least 2 mm dis-

tal to the tip of the ureteroscope to prevent damage to the lens. It is recommended to limit

the energy used when treating ureteral stones to minimize the risk of perforation. The

goal of the treatment is to create fragments that can be removed or fragments that are

likely to pass spontaneously. Attempts to reduce the stone to fragments smaller than

2 mm are not recommended, because damage to the mucosa may occur (27).

NEUMATIC

The Swiss lithoclast was the first pneumatic lithotrite, introduced in the early nine-

ties. It uses a “jackhammer” effect by which a small metal projectile in the hand piece

of the instrument is propelled by controlled bursts of compressed air against the head

of the metal probe at a frequency of 12 cycles per second. The probe tip is placed against

the stone, which fragments on impact. The discharged probe is brought back into its

former position by a piece of rubber bushing placed around the base of the probe.

Pneumatic devices are still the most popular forms of ureteral lithotripsy in Europe.

Probes for the pneumatic lithotrites are rigid and range from 2.4 Fr (0.8 mm) to 7.5

Fr (2.5 mm) in diameter. A flexible Nitinol probe has been developed recently that is able

to fragment calculi through semirigid and actively deflectable, flexible ureteroscopes

with no reported complications (32). However, use of flexible probes through deflected

ureteroscopes significantly decreases fragmentation power (33). Another improvement

of this technology has been the introduction of a suction device connecting to the lithoclast

probe that allows evacuation of small stone fragments (34).

Successful fragmentation of ureteral stones of various compositions has been reported

in 73–96% of cases (35,36). This is similar to reported success rates of EHL.

Pneumatic lithotripsy may be more advantageous for large and hard stones encoun-

tered during percutaneous nephrolithotomy or cystolitholapaxy. Although less practi-

cal for ureteral lithotripsy, pneumatic devices have a significantly lower risk of ureteral

perforation compared to EHL, ultrasonic, and laser lithotripsy (37). On average, the

risk of ureteral perforation is less than 1% (35,36,38). Furthermore, because no heat is

produced during lithotripsy, the risk of thermal injury to the urothelium is eliminated.

Another advantage of pneumatic lithotrites is their relatively low cost and low main-

tenance. Although they are more expensive than EHL, there are no disposable costs and

the probes have a long life span. Disadvantages include the rigid nature of the probe,

which requires straight working channel rigid ureteroscopes with an offset eyepiece.

Also, pneumatic ureteral lithotripsy is accompanied by a relatively high rate of stone

propulsion up to 17% (38). Technical difficulty may be encountered if the stone can not

be stabilized in a dilated ureter. Fixation of ureteral stones with a basket or proximal

placement of a ureteral occlusion balloon is sometimes necessary. Fixation of the stone

is rarely difficult in the kidney or the bladder.

602 El-Hakim, Tan, and Smith

ULTRASONIC

Ultrasonic lithotripsy is a major modality for the treatment of kidney stones during

percutaneous nephrolithotomy, however, its use is limited in ureteroscopy owing to the

nonflexible probe design and relatively large diameter. The ultrasound probe works by

exciting a piezoceramic plate located in the ultrasound transducer. The plate then reso-

nates and generates ultrasonic waves at a frequency of approx 23–25,000 Hz. Ultrasound

energy is transformed into longitudinal and transverse vibrations of the hollow steel

probe, which transmit the energy to the calculus. The ultrasonic lithotriptor system is

connected to a suction pump so that debris from the stone are removed continuously with

irrigating fluid during lithotripsy. In addition, the flow of fluid through the hollow probe

serves to cool the instrument. Heat may develop at the end of the probe because irrigation

is limited during ureteroscopy and because the small probe lumen is more prone to

clogging. Ultrasonic probes are available at sizes ranging from 2.5 to 12 Fr. The 2.5-Fr

probe is solid and has no hollow center for suction. Therefore, when it is used in the

ureter, heat dissipation is slow. Bending of the probe results in energy loss at the con-

vexity of the kink (39).

The advantage of ultrasonic lithotripsy is simultaneous fragment removal. However,

the rigid nature of ultrasonic probes and their large diameter limits its use in ureteroscopic

lithotripsy. An ureteroscope with an offset eyepiece and a large working channel is

required. Excellent results have also been reported for distal ureteral stones easily acces-

sible to the rigid ureteroscope (33).

ASER

The special features of laser light allow considerable energy to be transmitted in a

highly concentrated manner. Lasers are named after the laser medium generating a

specific wavelength. Initial lithotrites used continuous-wave lasers that heated the stone

until vaporization occurs. Excessive temperature was needed to melt the stone making

continuous-wave lasers clinically unusable (40). The development of pulsed lasers solved

this dilemma. Pulsed energy generates very high power density at the stone surface with

concomitant heat dissipation.

Pulsed lasers create a “plasma” bubble that generates a shock wave responsible for

stone fragmentation, except for holmium laser (41). The holmium:YAG laser pro-

duces an elongated cavitation bubble that generates a weak shock wave compared with

the strong shock wave produced by other pulse lasers. In fact, Holmium laser lithot-

ripsy occurs primarily through a photothermal mechanism that causes stone vaporiza-

tion (42). The first commercially available laser lithotrite was the pulsed-dye laser,

which employed a coumarin green dye as a liquid laser medium. The 200-µm flexible

fiber allowed the use of flexible ureteroscopes. Overall success rates were 80–95%

(42). However, calcium oxalate monohydrate stones were more difficult to treat and

yielded larger fragments (43), and cystine stones did not absorb the laser wave length

and were not fragmented (44). Other limitations of the coumarin pulsed-dye laser

included the initial high cost, and the cost of toxic disposable dye and maintenance.

The flashlamp pumped Q-switched alexandrite laser was proposed as an alternative to

the pulsed-dye laser. It operated at a wavelength of 750 nm as opposed to the coumarin

laser wavelength of 504. This solid-state laser was equally efficacious, compact, and

with no toxic chemicals.

Recent developments in laser lithotripsy led to the Holmium:YAG laser (Fig. 7). The

properties of this laser make it a great clinical tool: monochromatic, directional and

Chapter 30 / Ureteroscopy 603

coherent. The holmium laser operates at a wavelength of 2140 nm in the pulsed mode,

which is highly absorbed by water and results in superficial cutting or coagulation. The

zone of thermal injury associated with laser ablation ranges from 0.5 to 1.0 mm in depth

(45). The Holmium:YAG laser, similar to the EHL, allows the use of flexible instruments

throughout the entire collecting system. However, when compared with EHL, holmium

laser is safer and more efficient. Whereas EHL may cause injury to the ureter even when

the probe is activated several millimeters away from the ureteral wall, the holmium laser

can be safely activated at a distance of 0.5–1 mm from the ureteral wall (46). The ability

of the holmium laser to fragment all stones regardless of composition is a clear advantage

over the pulsed-dye laser. Successful fragmentation of ureteral stones of all composi-

tions is reported to be up to 100% of cases, with a stone-free rate as high as 95%.

Perforation and stricture rates are 1.1% and 1.2%, respectively (47,48).

Currently, the holmium laser is the most effective and versatile intracorporeal

lithotriptor with a good margin of safety. Further advantages include significantly smaller

stone fragments compared with other lithotrites, resulting in small stone debris, which

are easily irrigated and reduce the need for stone retrieval. Retropulsion is less likely

owing to the weak shock wave. In addition, the holmium laser is more compact than the

coumarin laser, requires minimal maintenance, and is ready for use 1 min after it is turned

on. The major disadvantage of the holmium laser is the initial high cost of the device and

the cost of the laser fibers. However, the holmium laser has multiple soft tissue appli-

cations and can be used for treating benign prostatic hyperplasia, strictures, and urothelial

tumors.

During lithotripsy, the laser fiber should be placed on the stone surface before acti-

vating the laser (Fig. 2D). Caution must be exercised when operating the holmium laser

near a guidewire or a basket because it is capable of cutting through metal. Furthermore,

the laser fiber should extend at least 2 mm beyond the tip of the endoscope to avoid

damage to the lens or the working channel of the endoscope. Holmium laser fibers are

available in 200-, 365-, 550-, and 1000-µm diameters, as well as end- or side-firing

Fig. 7. Two holmium:YAG laser generators from different manufacturers.

604 El-Hakim, Tan, and Smith

fibers. However, only the 200- and 365-µm diameter fibers are used for flexible

intracorporeal lithotripsy. Treatment should be started with low energy. Usually 0.6–1.2

Joules at a rate of 5–15 Hz provides adequate lithotripsy. High-pulse energy narrows the

safety margin and may increase stone retropulsion and mucosal damage. Stone fragmen-

tation with the holmium laser occurs by small perforations at the surface of the stone. The

surgeon should move the laser fiber over the stone surface, vaporizing the stone rather

than fragmenting it until fragments are small enough to pass spontaneously (Fig. 2E) or

are able to be safely retrieved (Fig. 2F). Fragments larger than 4 mm are produced by all

types of endoscopic lithotrites, with the exception of the Holmium:YAG laser (49).

Other laser lithotriptors are currently being developed. The erbium:YAG (Er:YAG)

laser operates at a wavelength of 2940 nm and fragments stones through a photothermal

mechanism like the Ho:YAG laser. Experimental studies demonstrated that Er:YAG

lithotripsy is more efficient than Ho:YAG lithotripsy because optical energy is better

absorbed by urinary calculi at 2940 nm wavelength compared with 2140 nm. However,

a major limitation of Er:YAG lithotripsy to date has been the lack of clinically useful

optical fibers to transport the laser energy through endoscopes (50).

ASER SAFETY

The cornea will absorb laser energy. Under prolonged exposure, aqueous flare, cata-

racts, or corneal burn may occur. The holmium laser beam is invisible. All procedure

room personnel, including the patient, should wear appropriate laser safety eyewear

while the laser is in operation. Access to the operation room must be restricted and laser-

warning signs should be posted at all entrances. Ocular hazards can result from direct,

reflected, or scattered laser exposure. In fact, the holmium laser properties are such that

when using energy levels applied for stone disease (i.e., less than 15 W), the operator’s

retina might be damaged only if it were positioned at a distance of 10 cm or less from

the fiber (26). The required eye protection for coumarin green laser causes pronounced

blue-yellow color confusion, whereas alexandrite laser causes mild red-green color

confusion. The eyewear for holmium laser does not compromise color vision (51).

Laser exposure on unprotected skin may cause skin injuries. Pigment darkening,

photosensitive reactions, and severe skin burns may occur. Moreover, the laser

lithotriptor should not be used in the presence of flammable anesthetics. All room per-

sonnel should be trained in laser safety.

A potential side effect of holmium laser lithotripsy is the production of cyanide gas

when uric acid stones are treated; this has been reported in vitro. However, review of

clinical experience suggests no significant cyanide toxicity from holmium laser litho-

tripsy (52).

PEARLS AND TRICKS

On many occasions, an urologist is challenged in obtaining ureteral access in patients

with abnormal ureteral anatomy. Patients may present with a ureteral orifice that is

difficult to find or an orifice that is stenotic and strictured from previous surgery.

Carefully evaluate for ureteral anomalies related to number (duplication), position

(ectopy), or morphology (ureterocele); watch for urine efflux. Severe inflammation

within the bladder and mucosal edema may hide the ureteral orifices. This is commonly

seen in patients with cystitis, or a chronic indwelling catheter. Locating the ureteral

orifice is also difficult in a patient with prior ureteral reimplantation. In Politano-

Leadbetter or Anderson ureteral reimplantation, laterality of the ureters is maintained,

Chapter 30 / Ureteroscopy 605

and the orifice is located either in the orthotopic position or slightly closer to the bladder

neck. In patients who have undergone a Cohen cross-trigonal reimplantation, the ure-

teral orifice is found exiting the contralateral side of the bladder. In the extavesical

seromuscular Lich-Gregoire technique, commonly used in kidney transplants, the ure-

ter enters near the posterior wall or the dome of the bladder. In patients who have

undergone ileal interposition, the ileal segment is usually anastomosed to the postero-

lateral wall of the bladder. The anastomosis is often patulous and is easily visualized by

endoscopy. Regardless of the situation, caution must be taken when attempting ureteral

access in patients whose distal ureteral anatomy is abnormal. The use of a flexible

cystoscope is of great help in these difficult cases to reach and access the ureteral orifice

in the most optimal direction. Straight or angled tipped hydrophilic wires offer the best

chance to secure access. They can later be exchanged for a regular guidewire over an

open ended ureteral catheter. In cases where the orifice is obscured by inflammation,

edema, or scarring, intravenous indigo carmine or methylene blue helps to locate a

hidden orifice.

Benign Prostatic Hyperplasia Median Lobe

One of the more common, and often difficult, tasks is locating the ureteral orifices in

a patient with benign prostatic hyperplasia and a large median lobe. The transmural

ureter often assumes a J-hook configuration as it enters the bladder.

If the ureteral orifice is not readily identified, first make sure the irrigation fluid is

clear. Rotate the cystoscope 180 to use the rounded beak of the scope to gently retract

the middle lobe off the interureteric ridge and expose the orifice. This configuration also

provides a more direct angle into the distal bend of the ureter, allowing for easier passage

of the wire. A 70 lens can aid viewing around a large median lobe or finding an ectopic

orifice. A flexible cystoscope can also be helpful as mentioned before. Occasionally,

using an angled tipped guidewire that is directed gently back and forth on the inter-

ureteric ridge can sometimes reveal the ureteral orifice opening and find its way into the

distal ureter. A rigid ureteroscope may also be used to introduce a guidewire into a ureter.

If all these maneuvers fail, percutaneous renal access with antegrade passage of a

guidewire down the ureter and into the bladder may become necessary.

Ureteral Kinks

Ureteral kinks sometimes pose a difficult problem in securing access and progressing

proximally during ureteroscopy. These kinks are secondary to multiple causes including

abdominal masses, prior retroperitoneal or endoscopic surgery, distal obstruction and

elongation of the ureter, and vascular abnormalities.

First, an attempt is made to pass a hydrophilic guidewire past the area of concern. An

angled tipped wire over an open-ended ureteral catheter offers a good chance to steer past

the kink. Alternatively, different angiocatheters with various tip configurations can be

used to support the glide wire and orient its tip in the desired direction. We find the Cobra

angiocatheter very useful in these situations. Placing the patient in a steep Trendelenberg

position slightly displaces the kidneys cephalad and may help straighten the ureter. If

these maneuvers fail, inflating a balloon dilator distal to the ureteral kink and exerting

gentle traction under fluoroscopic guidance can align the ureter and facilitate passage of

the guidewire. Once a glide wire is passed beyond the kink, it should be exchanged to

a regular wire, or preferably to a superstiff wire, to straighten the ureter.

606 El-Hakim, Tan, and Smith

SUMMARY

Ureteroscopy and intracorporeal lithotripsy is highly successful thanks to multiple

modern instruments and tools. However, always remember that the ureter is fragile and

if there are significant technical difficulties in achieving the goal, place a stent and come

back at a later date. Passive ureteral dilation usually ensues within 48 h.

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