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Surgical Management of Urolithiasis

Charles T. Durkee, MDT, Anthony Balcom

Department of Urology, Medical College of Wisconsin, 9000 West Wisconsin Avenue,#606, Milwaukee WI 53226, USA

There is an increase in the number of cases of urolithiasis being seen at

pediatric centers and a perception that the overall incidence of stones is also

increasing [1,2]. Admissions for stone disease are between 1 per 1000 to 1 per

7600 patients to pediatric centers, with rates showing a geographic variation.

This rate is one tenth of that seen in the adult population [3]. This rate, along

with a continued evolution in the evaluation and management of stone disease,

makes pediatric urolithiasis a timely topic.

The signs and symptoms of urolithiasis vary by age group. Infants may present

with a urinary tract infection, gross or microscopic hematuria, or nonspecific

visceral pain. Associated underlying anatomic abnormalities are much more

common in the early childhood group. Renal stones are more prevalent in infants

and young children, whereas ureteral calculi are more prevalent in older children

and adolescents [4]. Classic renal colic is the more common presentation in older

age groups. Hematuria is relatively common throughout all age groups [5]. Dif-

fering evaluation and management strategies are required for these groups.

The goal of treatment is to achieve a stone-free status whenever possible. If

present, anatomic abnormalities are addressed. A complete metabolic evaluationshould be undertaken to minimize the risk for recurrent stone formation in all

patients, including individuals with anatomic abnormalities. In this section we

describe various current surgical approaches and their indications.

Shock wave lithotripsy

The introduction of shock wave lithotripsy (SWL) in 1982 has revolutionized

the surgical treatment of urolithiasis [6]. Although there are various types of

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doi:10.1016/j.pcl.2006.02.009 pediatric.theclinics.com

T Corresponding author.

E-mail address: [email protected] (C.T. Durkee).

Pediatr Clin N Am 53 (2006) 465477
http://dx.doi.org/10.1016/j.pcl.2006.02.009http://pediatric.theclinics.com/mailto:[email protected]:[email protected]://pediatric.theclinics.com/http://dx.doi.org/10.1016/j.pcl.2006.02.009http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-

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machines, all units function on the principle of generating and focusing shock

wave energy at a focal point that is directed at the stone. The stone is pulverized

and the resulting fragments are passed. Important variables in the design of themachine include the type of shock wave generator technology, the size of body

surface area through which the energy is delivered, the size of the focal area

where the energy is concentrated, the method by which a patient is coupled to the

machine, and the imaging device.

The safety and efficacy of SWL are well established in the adult population.

Results in the adult literature show that the success rate approaches 80% when the

stone burden is smaller than 2 cm [7]. The rate of residual fragments increases

significantly as stone burden increases.

Although the pediatric experience is more limited, available data point to asafety and efficacy profile similar to adult outcomes. In one large series,

344 children were treated over a 12-year period. They achieved a 92% stone-free

rate for stones located in the renal pelvis that were smaller than 1 cm, 68% stone-

free rate for stones from 1 to 2 cm, and a 50% stone-free rate for stones larger

than 2 cm. Stone-free rates were lower for patients when the stones were located

in the calyces. An average of 1.9 treatment sessions was required to achieve these

results [8].

Young children and even infants can be treated safely [9]. Precautions for

children include the use of foam tape or similar modifications for protection ofthe lungs to prevent contusion and lower power settings during treatment. Power

settings equal to those used on adult patients have been well tolerated without

increased complications, however, presumably because the high water content of

the tissue in young children makes the tissue more resilient and less vulnerable to

damage [10,11]. In a series of 40 consecutive pediatric patients, immediate renal

ultrasounds after treatment found six small hematomas. All hematomas resolved

on follow-up. This same study showed no change in the glomerular filtration rate

of the treated kidney as determined by technetium 99m diethylenetriaminepenta-

acetic acid (DPTA) scanning [12]. Pretreatment and posttreatment technetium99m dimercaptosuccinic acid (DMSA) scanning also have shown no evidence of

renal parenchymal scars developing after SWL [13].

The use of stents remains controversial. Most centers do not routinely place

stents when stone burden is less than 2 cm. Removal of a stent in this population

does require a second anesthetic agent in most cases, although pullout strings are

tolerated in some children [14].

Percutaneous lithotripsy

Percutaneous techniques for renal stone removal were introduced in the late

1970s, shortly before the advent of SWL. It was not until the 1990s that specific

instrumentation was adapted to pediatric patients [15]. This approach may be

used solely or in conjunction with SWL in patients with a large stone burden,

such as staghorn calculi. The procedure consists of gaining access to the

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collecting system of the kidney percutaneously, advancing a wire, and, using a

Seldinger technique, sequentially dilating the tract. Under the same setting or

during a second procedure, a nephroscope is introduced through the tract into thekidney. Stones are then removed or pulverized under direct vision. Percutane-

ous nephrolithotomy (PNL) is currently the main approach to complex upper

tract stones.

Most adult and pediatric centers perform access and tube placement in

radiology the day before the planned intervention, although some centers proceed

under a single anesthetic [16,17]. Rigid and flexible miniaturized scopes are

then introduced into the kidney (Fig. 1). Modalities for stone removal include the

Holmium laser, ultrasonic lithotripsy probes, and direct grasping and removal.

PNL also can be used in combination with SWL, with the major stone debulkingperformed percutaneously.

Stone-free rates can be expected in 80% to 90% of cases [15,16]. Rates may

very depending on the experience of the operator and the complexity of stones

that are treated. Stones within horseshoe kidneys also have been treated

successfully. Anomalous anatomy makes access and treatment more challenging

[18]. Major complications reported from the adult experience occur in

approximately 4% to 5% of cases [19], including urosepsis, bleeding, perforation

of the renal pelvis, and injury to adjacent organs. There is an occasional need for

conversion to an open procedure [17]. Follow-up DMSA and DTPA scanninghave shown no postoperative scarring and no compromise of renal function [16].

Although placement of a nephrostomy tube postoperatively has been standard

management, this concept is being challenged. In a small, prospective series in

adults, there were no increased complications, and a significant decrease in

postoperative pain and recovery time with the use of small tubes or no tubes

compared with the use of a traditional large nephrostomy tube [20]. Fibrin

Fig. 1. Percutaneous nephroscopy.

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sealants also have proved to be effective hemostatic agents and urinary sealants,

obviating the need for a postoperative nephrostomy tube [21].

Ureteroscopy

Ureteroscopy is ideally suited for removal or fragmentation of distal ureteral

stones. It is also being used with increased frequency for smaller upper tract

stones when SWL is not effective because of inability to visualize the stone or

because stone composition or location makes it resistant to SWL fragmentation.

The evolution of progressively smaller diameter ureteroscopic instrumentation

rigid and flexiblehas made the pediatric ureter and kidney more accessible toendoscopic examination. Rigid scopes can bend without losing visualization

and have improved optics and larger working channels. Flexible scopes have

true active deflectionup to 2708along with improved optics and larger

working channels. Flexible scopes, in particular, remain fragile and may require

frequent repair.

Once visualized, a stone can be removed effectively. The Holmium laser, with

energy delivered through fibers as small as 200 mm, fragment virtually all stones

visualized (Fig. 2) [22,23]. Newer generation nitinol stone baskets also have

enhanced flexibility, smaller diameters, and wire memory that minimizedistortion of the basket and allow safe removal of fragments.

The smaller diameter ureteroscopes can be passed safely in most cases without

the need for surgical dilation of the system. In some cases, balloon dilation of the

distal ureter is performed. A semi-rigid access sheath occasionally is used for

flexible ureteroscopy. Preoperative ureteral stenting can be performed to dilate

the ureter, with a return to the operating room within a few days if initial

instrumentation cannot be accomplished safely.

Fig. 2. Holmium laser lithotripsy of ureteral stone.

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Postoperative stenting is controversial. Stents are placed after instrumentation

because of minor trauma to the ureteral wall, postoperative edema to the ureteral

wall that obstructs the ureter, or facilitation of passage of small residual stonefragments. Children can experience significant discomfort from the stents and

seem to tolerate the stents more poorly than their adult counterparts. The adult

experience has shown that patients with stents placed after uncomplicated distal

ureteroscopy have more flank pain, bladder pain, urinary symptoms, and narcotic

usage than unstented patients in a randomized prospective study [24]. Most

surgeons opt for not placing a stent in simple, uncomplicated ureteroscopy in

which the scope passed easily. Complications are uncommon in contemporary

series [14,25]. Simple perforation can occur and is easily managed by a tempo-

rary stent. More significant tears and ureteral avulsion are rarely encountered.Instrumentation never should be forced, and if difficulties are encountered, a stent

should be left indwelling for passive dilation of the ureter with a return to the

operating room a few days later. Postoperative stricture or ureteral reflux is rarely

encountered, and postoperative imaging is reserved for more complicated cases.

Laparoscopy

The role of laparoscopy in the treatment of renal and ureteral calculi has notyet been well defined and continues to evolve. With increasing sophistication of

laparoscopic techniques and instrumentation, indications for laparoscopic stone

removal may expand. For example, laparoscopic stone removal and concomitant

pyeloplasty for ureteropelvic junction obstruction have been reported in a series

of 19 adult patients [26]. Successful transperitoneal laparoscopic pyelolithotomy

has been described in eight failed pediatric percutaneous cases. These patients

primarily had a large stone burden in nondilated systems. An 87% success rate

was achieved without major complications [27].

Management of renal stones

In the absence of major medical contraindications to therapy, almost all

patients are candidates for treatment once a renal stone has been identified. The

high rate of associated metabolic abnormalities, structural anomalies, and likely

growth of a retained stone all dictate an active approach in pediatric patients. The

goal of surgical therapy is to achieve a stone-free status. Balanced against this is

the attendant risk to patients of prolonged or multiple interventions. The currentsurgical modalities allow effective treatment with minimal morbidity and maxi-

mum safety. Open surgery rarely becomes required.

Treatment choices are somewhat dictated by the experience of the operator.

Important variables in deciding on the best treatment option include size of the

stone, location of the stone, and, if known, stone composition. Renal anatomy,

including the presence or absence of hydronephrosis, other associated anomalies,

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and the medical condition of the patient enter into the surgical decision-making

process. Age of a patient is not a major determinant in most cases, because all

modalities have been used safely in all age groups (Table 1). It is useful to stratify

some of these variables into categories for treatment options.

Stone treatment by size

Stones smaller than one centimeter

There is near unanimity on the use of SWL on a small renal calculus, regard-

less of age. Success rates defined as a stone-free status of 80% to 90% are

achievable [7]. Stents are rarely placed.

Stones one to two centimeters

Approximately two thirds of stones can be expected to clear with SWL in thiscategory. There is a higher retreatment rate and the need for ancillary procedures.

Lower pole calculi clear less effectively as stone size approaches 2 cm. Invasive

techniques, particularly PNL, become more effective modalities. In most cases, a

stent is not placed.

Stones larger than two centimeters

In most cases, PNL is the treatment of choice. Success rates with SWL

monotherapy start to fall below 50%, and multiple treatments become the norm[7]. One subgroup, however, deserves particular mention. Children younger than

age 5 with staghorn calculi have a high success rate with SWL. In one series,

87.5% of patients were stone free after one or two sessions. Stents were not

routinely placed. Success rates diminish as a child becomes older and PNL again

becomes a more attractive option [28]. Staghorn calculi in adults typically do not

respond well to SWL monotherapy.

Table 1

Primary surgical treatment options versus stone size and location

Stones Shock wave lithotripsy Ureteroscopy Percutaneous nephrolithotomyRenal

b1 cm Most common Optional Optional

12 cm Most common Optional Optional

N2 cm Optional Rare Most common

Lower pole

b1 cm Most common Optional Optional

N1 cm Optional Optional Most common

Ureteral

Proximal Most common Optional Occasional

Distal Optional Most common Rare

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Special considerations

Ureteropelvic junction (UPJ) obstruction

Stones are present in up to 8% of cases of UPJ obstruction [29]. Most patients

undergo an open pyeloplasty and successful removal of the stones. The dilated

anatomy lends itself to successful removal of the stones. The hydronephrotic

kidney is also amenable to percutaneous access, which facilitates PNL and

endoscopic incision of the UPJ obstruction. Laparoscopy may play an increasing

role in the future [26]. Metabolic evaluation and follow-up are important. In a

group of 22 patients with stones and a coexisting UPJ obstruction, 68% had

recurrent stones and 87% had an identifiable metabolic abnormality [30].

Calyceal diverticulum

A calyceal diverticulum is a congenital outpouching of the calyx, typically

with a narrow neck leading to the diverticulum. Although they are uncommon,

diverticula are at risk for developing stones. The narrow neck prevents effective

stone passage with SWL, and in most centers PNL is the preferred treatment[31].

This approach also allows ablation of the diverticulum to prevent future stone

formation [32].

Lower pole calculus

Controversy exists regarding the efficacy of SWL of lower pole stones.

Although fragmentation can be achieved, their passage may be impeded by the

dependent location of the calyx and a frequently associated narrow infundibulum.

Multiple studies, including a meta-analysis, have shown decreased lower pole

clearing rates of stones compared with other locations within the kidney [33].

Other studies have shown similar clearance rates regardless of location [34,35].PNL has been the standard treatment option, although continued refinement of

the flexible ureteroscope has made ureteroscopy a viable option [36].

Infants

Stones and the subsequent need for treatment in infants are uncommon (Fig. 3).

Treatment also may be delayed in asymptomatic infants with sterile urine to a

later age if carefully monitored. SWL is commonly the preferred treatment

modality when intervention is indicated. Safety and efficacy have been demon-strated [9,28], and age alone does not represent a contraindication to treatment.

The infant body size requires modifications of positioning and coupling to the

shock wave generator and protection of the lung fields with foam tape. PNL may

be an alternative modality in this age group, especially when hydronephrosis is

present [37]. In the absence of a dilated ureter, ureteroscopy may be more

problematic in the infant ureter. The small ureteral diameter can be overcome

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partially by placing a stent to dilate the ureter passively before the definitive

ureteroscopic procedure.

Stone composition

Certain types of stones are less amenable to fracturing. Stone matrix may

influence the propagation of the shock wave energy inside the stone [38]. Cys-

tine, brushite, and calcium oxalate monohydrate stones are all resistant to frac-

turing by SWL (Fig. 4). Invasive techniques are more likely to be required in

these cases. Struvite, calcium oxalate dihydrate, and uric acid stones are rela-

tively fragile and break more readily with SWL [39].

Fig. 3. Obstructing ureteral calculus in a premature infant.

Fig. 4. Cystine staghorn calculus.

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Management of ureteral stones

Ureteral calculi are invariably symptomatic. Younger patients have lesslocalizing symptoms and less ability to convey these symptoms. Younger patients

are less likely to present with a ureteral calculus, however, and are more likely to

have renal stones that often have less symptoms. In one study that involved

children younger than 5 years old, 68% presented with renal calculi and 32%

had ureteral calculi. Children aged 6 to 10 presented with ureteral calculi 64%

of the time, and children over age 10 presented with ureteral calculi in 82% of

cases [4].

Stone size is a major determinant in predicting spontaneous stone passage.

Ureteral stone size at presentation is remarkably consistent regardless of age ofpresentation. Ureteral stones averaged 4.5 mm for children younger than age 5

compared with 3.2 to 3.5 mm for older children [4]. The ureter in a pediatric

patient is nearly as efficient at passing fragments as the adult ureter. For example,

upper tract stones treated with SWL pass as efficiently with no increase in

complications compared with adults with similar stone burden [40]. In guidelines

established for the treatment of ureteral calculi in adults, 71% to 98% of stones

smaller than 5 mm spontaneously pass [41]. Pediatric patients also effectively

pass stones up to 5 mm, and this passage rate is independent of age [4]. One

speculation is that the pediatric ureter is more distensible than the adult ureter andis more efficient at passing stones [42,43].

Stone location at presentation is another important factor. Stones located in the

proximal ureter have a significantly lower likelihood of spontaneous passage

(29%48%), whereas stones in the distal ureter or at the ureterovesical junction

have a passage rate of 75% to 98% [41,44].

Duration of symptoms also has been shown to be another important indepen-

dent variable for spontaneous passage. An artificial neural network model in

adults deemed duration of symptoms to be the single most important variable in

predicting passage [45]. A review article found that stones rarely passed ifsymptoms persisted beyond 4 weeks [46].

In the absence of complicating factors such as a urinary tract infection or un-

relenting pain, observation is initially recommended for stones 5 mm or smaller.

In adults, 95% of spontaneously passed stones do so within the first 40 days

[47]. An observation period of 6 weeks seems reasonable in uncomplicated

cases. Permanent adverse effects on the kidney after a period of observation

are rarely reported. Presumably, in a patient with minimal symptoms, the ureter

has become dilated and high-grade obstruction does not persist.

Alpha-adrenergic blockers, such as tamsulosin, terazosin, and doxazosin, havebeen shown to facilitate stone passage in adults by decreasing ureteral pressure

below the stone and decreasing the frequency of the peristaltic contractions of the

obstructed ureter[48]. These agents decrease the amount of pain experienced by a

patient, decrease the time of passage of the stone, and increase the spontane-

ous passage rate [49]. Their safety and efficacy have not been demonstrated

in children.

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When intervention is indicated, the variables described previously dictate

choices. Patients with infection and sepsis must be drained immediately with

either a ureteral stent or nephrostomy tube, and definitive treatment is typicallydelayed until the infection is controlled. Most patients with a proximal ureteral

stone are candidates for SWL if the stone is visualized on a plain film of the

abdomen [41]. The distal ureteral calculus can be treated with either ureteroscopy

or SWL. Ureteroscopy has a marginally higher success rate with a single treat-

ment but also has a marginally higher complication rate than SWL [41]. Although

no adverse effects have been proven, it is attractive to avoid the increased

radiation exposure and scatter effects of SWL in the pelvis with the proximity of

the gonads (Table 1).

Residual fragments after treatment

A stone-free status is the preferable outcome after treatment. Failure of all

stone fragments to clear completely has led to the concept of insignificant

fragments, generally defined as fragments smaller than 5 mm, although no

absolute standard exists. Even the definition of stone free is problematic.

Fragments will clear for months after SWL treatment of larger stones. Time of

follow-up influences outcome. It can be difficult at times to distinguish betweenresidual fragments and new stones. Results also vary widely depending on the

imaging modality used. Spiral CT scanning is considered the most accurate

imaging modality available. The radiation dosage and cost are significantly

higher than in other imaging techniques, however. Compared with spiral CT, a

KUB detected only 48% of stones in adults [50]. In one group of children

younger than 8 years old, spiral CT detected 57 stones, whereas ultrasound

detected only 34 stones [51].

Patients with residual fragments are at risk for growth of the fragments

and symptomatic episodes. A group of 160 adult patients who had residualfragments 4 mm or smaller after SWL was followed for 1.6 to 88.8 months

(mean, 23 months). Forty-three percent of the patients had a symptomatic episode

or required intervention, and 18% demonstrated growth of the fragments

[52]. Data are relatively sparse on the outcomes of pediatric patients with

residual stone fragments. In a group of 83 pediatric patients with 88 involved

renal units treated with SWL, 26 units were left with fragments of 5 mm or

smaller. With a follow-up of 3 to 198 months (mean, 46 months), 69% had either

symptomatic episodes or fragment growth [53]. Most residual fragments are

not insignificant.Equally important is the recognition of metabolic disorders in patients

with residual fragments. The presence of metabolic disorders is a strong predictor

of growth of residual fragments in pediatric patients [53]. In adults, patients

on medical therapy had a 16% incidence of stone growth of residual

fragments compared with a more than 50% growth rate in patients not on ther-

apy [54].

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Summary

Pediatric patients who have urolithiasis present unique challenges. Interven-tional techniques developed for adult patients have been adopted and adapted

to facilitate effective and safe treatment in this population. Management must be

stratified and individualized, taking into account the many factors described

in this article. Long-term follow-up and metabolic evaluation are essential compo-

nents of the overall treatment strategy. Interventional management will continue

to evolve with progressive refinements in instrumentation and techniques.

References

[1] Minevich E. Pediatric urolithiasis. Pediatr Clin North Am 2001;48(6):1571 6.

[2] Kroovland RL. Pediatric urolithiasis. Urol Clin North Am 1997;24:173 84.

[3] Stapleton FB. Nephrolithiasis in children. Pediatr Rev 1989;11:21 30.

[4] Pietrow PK, Pope JC, Adams MC, et al. Clinical outcome of pediatric stone disease. J Urol

2002;167(2 Part 1):6703.

[5] Milliner DS. Urolithiasis in pediatric patients. Mayo Clin Proc 1993;68(3):241 8.

[6] Chaussy CG, Schmeidt E, Jochman D, et al. First clinical experience with extracorporeally

induced destruction of kidney stones by shock waves. J Urol 1982;131:41720.

[7] Lingeman JE, Lifshitz DA, Evan AP. Surgical management of urinary lithiasis. In: Walsh PC,Retik AB, Vaughan ED, et al, editors. Campbells urology. 8th edition. Philadelphia7 WB

Saunders; 2002. p. 33678.

[8] Muslumanoglu AY, Tefekli A, Sarilar O, et al. Extracorporeal shock wave lithotripsy as first line

treatment alternative for urinary tract stones in children: a large scale retrospective analysis.

J Urol 2003;170(6 Part 1):24058.

[9] Shukla AR, Hoover DL, Homsey YL, et al. Urolithiasis in the low birth weight infant: the role

and efficacy of extracorporeal shock wave lithotripsy. J Urol 2001;165(6, Part 2):23203.

[10] Lottman HB, Archambaud F, Traxer OB. The efficacy and parenchymal consequences of

extracorporeal shock wave lithotripsy in infants. BJU Int 2000;85(3):311 5.

[11] Orsola A, Diaz I, Caffaratti J, et al. Staghorn calculi in children: treatment with monotherapy

extracorporeal shock wave lithotripsy. J Urol 1999;162(3 Part 2):122933.[12] Goel MC, Baserge NS, Babu RV, et al. Pediatric kidney: functional outcome after extracorporeal

shock wave lithotripsy. J Urol 1996;155(6):20446.

[13] Lottmann HB, Archambaud F, Hellal B, et al. 99m Technetium-dimercapto-succinic acid

renal scan in the evaluation of potential long-term renal parenchymal damage associated with

extracorporeal shock wave lithotripsy in children. J Urol 1998;159(2):521 4.

[14] Minevich E, DeFoor W, Reddy P, et al. Ureteroscopy is safe and effective in prepubertal chil-

dren. J Urol 2005;174(1):2769.

[15] Jackman SV, Docimo SG, Bishoff JT, et al. The mini-perc technique: a less invasive

alternative to percutaneous nephrolithotomy. J Urol 1999;161(4S):372.

[16] Dawaba MS, Shokeir AA, Hafez AT, et al. Percutaneous nephrolithotomy in children: early

and late anatomical and functional results. J Urol 2004;172(3):107881.[17] Bawady H, Salama A, Eissa M, et al. Percutaneous management of renal calculi: experience

with percutaneous nephrolithotomy in 60 children. J Urol 1999;162(5):1710.

[18] Raj GV, Auge BK, Weizer AZ, et al. Percutaneous management of calculi within horseshoe

kidneys. J Urol 2003;170(1):4851.

[19] Albertsen PC. Major complications after percutaneous nephrostomy: lessons from a department

audit. J Urol 2004;172(5 Part 1):21112.

[20] Desai MR, Kukreja RA, Desai MM, et al. A prospective randomized comparison of type of


7/28/2019 s0031395506000253_2

12/13

nephrostomy drainage following percutaneous nephrostolithotomy: large bore versus small

bore versus tubeless. J Urol 2004;172(2):565 7.

[21] Noller MW, Baughman SM, Morey AF, et al. Fibrin sealant enables tubeless percutaneous

stone surgery. J Urol 2004;172(1):1669.

[22] Reddy PP, Barrieras DJ, Bagli DJ, et al. Initial experience with endoscopic holmium laser

lithotripsy for pediatric urolithiasis. J Urol 1999;162(5):1714.

[23] Wollin TA, Teichman JM, Rogenes VJ, et al. Holmium:Yag lithotripsy in children. J Urol

1999;162(5):1717.

[24] Borboroglu PG, Amling CL, Schenkman NS, et al. Ureteral stenting after ureteroscopy for

distal ureteral calculi: a multi-institutional prospective randomized controlled study assessing

pain, outcomes and complications. J Urol 2001;166(5):1651 7.

[25] VanSavage JG, Palanca LG, Andersen RD, et al. Treatment of distal ureteral stones in

children: similarities to the American Urological Association guidelines in adults. J Urol 2000;

164(3 Part 2):108993.

[26] Ramakumar S, Lancini V, Chan DY, et al. Laparoscopic pyeloplasty with concomitant pyelo-

lithotomy. J Urol 2002;167(3):1378 80.

[27] Casale P, Grady RW, Joyner BD, et al. Transperitoneal laparoscopic pyelolithotomy after failed

percutaneous access in the pediatric patient. J Urol 2004;172(2):680 3.

[28] Lottmann HB, Traxer O, Archambaud F, et al. Monotherapy extracorporeal shock wave

lithotripsy for the treatment of staghorn calculi in children. J Urol 2001;165(6, Part 2):2324 7.

[29] Tekin A, Tekgul S, Atsu N, et al. Ureteropelvic junction obstruction and coexisting renal

calculi in children: role of metabolic abnormalities. Urology 2001;57(3):542 5.

[30] Husmann DA, Milliner DS, Segura JW, et al. Ureteropelvic junction obstruction with concurrent

renal pelvic calculi in the pediatric patient: a long-term followup. J Urol 1996;156(2S):7413.

[31] Cohen TD, Preminiger GM. Management of calyceal calculi. Urol Clin North Am 1997;24:8196.

[32] Shalhav AL, Soble JJ, Nakada SY, et al. Monotherapy extracorporeal shock wave lithotripsy

for the treatment of staghorn calculi in children. J Urol 1998;160:16359.

[33] Lingeman JE, Siegel YI, Nybius AW, et al. Management of lower pole nephrolithiasis: a critical

analysis. J Urol 1994;151:663.

[34] Chen RN, Streem SB. Extracorporeal shock wave lithotripsy for lower pole calculi: long-term

radiographic and clinical outcome. J Urol 1996;156(5):1572 5.

[35] Obek C, Onal B, Kantay K, et al. The efficacy of extracorporeal shock wave lithotripsy for

isolated lower pole calculi compared with isolated middle and upper caliceal calculi. J Urol

2001;166(6):20815.

[36] Schuster TG, Hollenbeck BK, Faerber GJ, et al. Ureteroscopic treatment of lower pole calculi:comparison of lithotripsy in situ and after displacement. J Urol 2002;168(1):435.

[37] Jackman SV, Hedican SP, Peters CA, et al. Percutaneous nephrolithotomy in infants and

preschool age children: experience with a new technique. Urology 1998;52(4):697 701.

[38] Pittomvils G, Vandeursen H, Wevers M, et al. The influence of internal stone structure upon the

fracture behaviour of urinary calculi. Ultrasound Med Biol 1994;20(8):803 10.

[39] Saw KC, Lingeman JE. Management of calyceal stones: lesson 20. AUA Update Series 1999;

20:1549.

[40] Gofrit ON, Pode D, Meretyk S, et al. Is the pediatric ureter as efficient as the adult ureter in

transporting fragments following extracorporeal shock wave lithotripsy for renal calculi larger

than 10 mm? J Urol 2001;166(5):18624.

[41] Segura JW, Preminger GM, Assimos DG, et al. Ureteral stones clinical guidelines panelsummary report on the management of ureteral calculi. J Urol 1997;158(5):191521.

[42] Jayanthi VR, Arnold PM, Koff SA. Strategies for managing upper tract calculi in young children.

J Urol 1999;162(3 Part 3):12347.

[43] Sigman M, Laudone VP, Jenkins AD, et al. Initial experience with extracorporeal shock wave

lithotripsy in children. J Urol 1987;138(4):83941.

[44] Coll DM, Varanelli MJ, Smith RC. Relationship of spontaneous passage of ureteral calculi to

durkee & balcom476

7/28/2019 s0031395506000253_2

13/13

stone size location as revealed by unenhanced helical CT. AJR Am J Roentgenol 2002;178(1):

1013.

[45] Cummings JM, Boullier JA, Izenberg SD, et al. Prediction of spontaneous ureteral calculus

passage by an artificial neural network. J Urol 2000;164(2):326 8.

[46] Hubner WA, Irby P, Stoller ML. Natural history and current concepts for the treatment of small

ureteral calculi. Eur Urol 1993;24:172.

[47] Miller OF, Kane CJ. Time to stone passage for observed ureteral calculi: a guide for patient

education. J Urol 1999;162(3):68890.

[48] Cervenakov I, Fillo J, Mardiak J, et al. Speedy elimination of ureterolithiasis in lower part of

ureters with the alpha 1 blockers-tamsulosin. J Urol Nephrol (Paris) 2002;34:25.

[49] Yilmaz E, Batislam E, Basar MM, et al. The comparison and efficacy of 3 different (alpha)

1-adrenergic blockers for distal ureteral stones. J Urol 2005;173(6):20102.

[50] Jackman SV, Potter SR, Regan F, et al. Plain abdominal x-rays versus computerized tomography

screening: sensitivity for stone localization after nonenhanced spiral computerized tomography.

J Urol 2000;164(2):30810.

[51] Oner S, Oto A, Tekgul S, et al. Comparison of spiral CT and US in the evaluation of pediatric

urolithiasis. Organe de la Societe Royale Belge de Radiologie 2004;87(5):21923.

[52] Streem SB, Yost A, Mascha E. Clinical implications of clinically insignificant stone fragments

after extracorporeal shock wave lithotripsy. J Urol 1996;155(4):118690.

[53] Afshar K, McLorie G, Papanikolaou F, et al. Outcome of small residual stone fragments

following shock wave lithotripsy in children. J Urol 2004;172(4, Part 2):16003.

[54] Fine JK, Pak CY, Preminger GM, et al. Effect of medical management and residual fragments

on recurrent stone formation following shock wave lithotripsy. J Urol 1995;153(1):2733.


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