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Special Article

Clinical Effectiveness Protocols for Imaging in the Managementof Ureteral Calculous Disease: AUA Technology Assessment

Pat Fox Fulgham,*,† Dean G. Assimos,* Margaret Sue Pearleand Glenn M. PremingerFrom the Texas Health Presbyterian Hospital of Dallas (PFF) and University of Texas Southwestern Medical Center (MSP), Dallas, Texas;Wake Forest University School of Medicine, Winston-Salem (DGA), and Duke University Medical Center, Durham (GMP),North Carolina

Purpose: This technology assessment addresses the optimal use of imaging inthe evaluation and treatment of patients with suspected or documented ureteralstones.Materials and Methods: A comprehensive literature search addressing 4 guidingquestions was performed for full text in English articles published betweenJanuary 1990 and July 2011. The search focused on major subtopics associatedwith the imaging of ureteral calculi, and included specific imaging modalitiesused in the diagnosis and management of ureteral calculous disease such asunenhanced (noncontrast) computerized tomography, conventional radiography,ultrasound, excretory urography, magnetic resonance imaging and nuclear med-icine studies. Protocols (in the form of decision tree algorithms) were developedbased on this literature review and in some instances on panel opinion. The 4questions addressed were 1) What imaging study should be performed forsuspected ureteral calculous disease? 2) What information should be ob-tained? 3) After diagnosis of a ureteral calculus, what followup imaging shouldbe used? 4) After treatment of a ureteral calculus, what followup imagingstudies should be obtained?Results: Based on these protocols, noncontrast computerized tomography is rec-ommended to establish the diagnosis in most cases, with a low energy protocoladvocated if body habitus is favorable. Conventional radiography and ultrasoundare endorsed for monitoring the passage of most radiopaque stones as well as formost patients undergoing stone removal. Other studies may be indicated basedon imaging findings, and patient, stone and clinical factors.Conclusions: The protocols generated assist the clinician in establishing thediagnosis of ureteral calculous disease, monitoring stone passage and followingpatients after treatment. The protocols take into account not only clinical effec-tiveness but also cost-effectiveness and risk/harm associated with the variousimaging modalities.

Abbreviations

and Acronyms

BMI � body mass indexCT � computerized tomographyhydro � hydronephrosisIV � intravenousIVP � excretory urographyKUB � plain x-ray of the kidneys,ureters and bladderMET � medical expulsive therapyNCCT � noncontrastcomputerized tomographysono � ultrasonographySWL � shock wave lithotripsy

Accepted for publication October 11, 2012.* Funding of the committee was provided by the

AUA and Committee members received no remu-neration for their work. Each member of the com-mittee provides an ongoing conflict of interest dis-closure to the AUA. All panel members completedCOI disclosures. Relationships that have expired(more than 1 year old) since the panel’s initialmeeting are listed. Those marked with (C) indicatethat compensation was received and relationshipsdesignated by (U) indicate no compensation wasreceived. Consultant/Advisor: Dean Assimos, Oxalo-sis and Hyperoxaluria Foundation (U); ScientificStudy or Trial: Dean Assimos, National Institutes ofHealth (C); Other-Investment Interest: Pat F. Ful-gham, Urology Clinics of North Texas (C); Other-Health Publishing: Dean Assimos, Med Review inUrology (C), Urology Times (C); Partnership: Pied-mont Stone (C).
Key Words: ureteral calculi, clinical protocols, diagnostic imaging
IMAGING for urinary calculous diseaseor the symptoms and signs associatedwith renal calculous disease accountsfor a significant portion of all imagingperformed by urologists.1 Patients
with suspected ureteral calculi often
0022-5347/13/1894-1203/0THE JOURNAL OF UROLOGY®

© 2013 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION AND RES

undergo repeated imaging studies be-fore, during and after treatment. Fur-thermore, because patients with uri-nary calculous disease are at highrisk for recurrence, repeat imaging is
common.2 Imaging accounts for 16%
http://dx.doi.org/10.1016/j.juro.2012.10.031Vol. 189, 1203-1213, April 2013

EARCH, INC. Printed in U.S.A.

† Correspondence: Department of Urology,Texas Health Presbyterian Dallas, Dallas, Texas75231 (e-mail: [email protected]).

Editor’s Note: This article is the

first of 5 published in this issue for

which category 1 CME credits can

be earned. Instructions for obtain-

ing credits are given with the

questions on pages 1608 and 1609.

www.jurology.com 1203

mailto:[email protected]

IMAGING FOR URETERAL CALCULI1204

of the total expenditure for each episode of care inthe management of urinary calculous disease.3

The EAU (European Association of Urology)-AUA(American Urological Association) Clinical Guide-lines for the Management of Ureteral Calculicover the evidence for clinical recommendationsfor the management of ureteral calculous disease.4

The American College of Radiology Appropriate-ness Criteria® document performance characteris-tics of various imaging studies for a given clinicalscenario.5 However, neither document addressescritical questions about how imaging technologyshould be used to maximize its effectiveness in thetreatment of patients with suspected or documentedureteral stones. This need served as the impetus forthe generation of this document.

Noncontrast computerized tomography has emergedas the most sensitive and specific modality for detect-ing ureteral calculi. Therefore, CT is frequently usedin the initial diagnosis of ureteral calculous disease,6

and to a lesser extent in the followup of known ure-teral calculi before and after treatment. Protocolsguiding imaging use in the management of ureteralcalculous disease are desirable because of the poten-tially harmful cumulative effects of radiation exposureto patients and the increased cost of high resolutionaxial imaging modalities.

There were 4 questions that provided the frame-work for the generation of the protocols in this doc-ument. 1) What imaging study should be performedfor suspected ureteral calculous disease? 2) Whatinformation should be obtained? 3) Once a ureteralcalculus has been diagnosed, what imaging modalityshould be used? 4) After treatment of a ureteralcalculus, what followup imaging studies should beobtained?

Current research fails to provide objective evi-dence to support the answers to some of these ques-tions about imaging. When objective evidence doesnot exist, the most effective course of action is theone that 1) has a reasonable probability of answer-ing the clinical questions at hand, 2) causes the leastpotential harm and 3) is cost-effective.

This Technical Assessment was developed to com-plement the EAU-AUA Clinical Guideline for theManagement of Ureteral Calculi.4 Methodology sim-ilar to that used in the development of AUA Guide-lines was used in the development of this technicalassessment. Unlike the Guidelines, these protocolsare based on clinical outcomes and consideration ofthe potential harm and cost-effectiveness of eachapproach. The clinical judgment of the physicianand the preferences and expectations of the patientshould continue to be the main determinants for theappropriate management of ureteral calculi. Practi-
cal considerations regarding the availability of im-
aging modalities in a given environment may influ-ence the choice of imaging study. However, of note,imaging is merely a tool to support clinical decisions.

To assist the clinician, decision tree algorithmshave been developed to select the most effective imag-ing study for a given clinical scenario. The scenariosare divided into 1) initial presentation, 2) followup orsurveillance of a known ureteral calculus and 3) fol-lowup after treatment or passage of a ureteral calcu-lus.

In summary, the protocols were developed specifi-cally to support clinicians in decision making for acommon clinical condition. These protocols are in-tended to enhance the effective use of imaging forsuspected or proven ureteral calculous disease by urol-ogists, emergency physicians and primary care physi-cians.

METHODOLOGY PROTOCOL

AND LITERATURE SEARCH

To assist in the development of these clinical effec-tiveness protocols, the panel crafted 31 guidingquestions classified by index patient, specific modal-ity and other factors. A comprehensive search of theliterature related to these guiding questions wasperformed for full text in English articles publishedbetween January 1990 and July 2011, and was tar-geted toward major subtopics associated with theimaging of ureteral calculi. (See Appendix A of thefull-text assessment for a full explanation of meth-odology and findings at http://www.auanet.org/content/media/imaging_assessment.pdf.)

INITIAL PRESENTATION

Patients who are suspected of having a ureteralstone frequently experience severe flank and occa-sionally abdominal pain. Noncontrast CT is the pre-ferred initial imaging study for the index patient(Level A Evidence). This selection is based on thereported median sensitivity and specificity forNCCT in the detection of ureteral calculi as 98% and97%, respectively, far superior to other imaging mo-dalities. Based on a review of the literature, thereappears to be consensus that the upper threshold forlow dose CT is 4 mSv. Low dose CT is preferred forpatients with a BMI of 30 kg/m2 or less as thismodification to standard CT imaging limits the po-tential long-term side effects of ionizing radiationwhile maintaining sensitivity and specificity at 90%or greater.7–9 However, low dose CT is not recom-mended for those with a BMI greater than 30 kg/m2

due to the lower sensitivity and specificity for detect-
ing ureteral stones.
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tion (d

IMAGING FOR URETERAL CALCULI 1205

When a ureteral calculus is demonstrated on CT,the stone is also identifiable on CT scout approxi-mately 50% of the time.10 A CT scout film is per-formed at a lower mA than a standard kidney, ure-ter, bladder film, accounting in part for the decreasedsensitivity in detecting stones. Standard KUB shouldbe performed when the stone is not demonstrated onthe CT scout as the stone will be seen in 10% of thesepatients.10,11 Followup KUB is obtained in thosewho are candidates for observation and in whom thestone was identified on the CT scout or initial KUBas it serves as an indicator of stone progression. Afollowup KUB should also be considered in those inwhom the stone was not seen on the initial CT scoutor KUB because it was positioned in the sacroiliacarea, thus limiting its visualization. Oblique filmsmay also be considered in such cases, either at thetime of the original CT or at followup, as theseimages may further facilitate stone visualization(fig. 1).

Certain parameters and findings should be as-sessed on CT imaging to facilitate subsequent man-agement decisions. The majority of patients with

Figure 1. Initial presenta

ureteral stones will have some degree of hydrone-

phrosis, a mean of 83% based on our review of 48studies. However, the presence of hydronephrosisdoes not predict the need for intervention.12 Thepresence or the degree of hydronephrosis has beenshown to influence results with shock wave litho-tripsy of ureteral stones, but this has less impact onureteroscopic removal.13–19

Alternative imaging modalities are considered forspecific patient groups. The combination of renal ul-trasonography and KUB is a viable option for a knownstone former who has previously had radiopaquestones. Sensitivities of 58% to 100% and specificities of37.2% to 100% have been reported for this combinationof modalities (Level C Evidence).20–26

Renal ultrasonography, despite its lower sensitiv-ity, is the preferred initial imaging modality for chil-dren because of radiation concerns.27 Low dose CT isa consideration if renal ultrasonography is not diag-nostic for children in whom a ureteral stone is sus-pected.28,29 Renal ultrasonography is the initial im-aging modality of choice for pregnant patients withsuspected colic.30–36 If the diagnosis is not estab-lished with this study during the first trimester,

ecision tree diagram 1)

magnetic resonance imaging without contrast should be


considered as second line imaging as the fetus ismost susceptible to potential radiation induced in-jury in the first trimester. Women in the second andthird trimesters are candidates for low dose CT ifultrasonography is not diagnostic.37 An AmericanCollege of Obstetricians and Gynecologists commit-tee on obstetric practice endorses the use of low doseCT when clinically indicated and notes that an ex-posure of less than 5 rads, a threshold well above theaverage for a low dose CT, is not associated with thedevelopment of fetal anomalies or fetal loss.38

OBSERVATION OF

KNOWN URETERAL CALCULUS

The chance of spontaneous passage of a known ure-teral calculus is based primarily on stone size andlocation. Perhaps the best study investigating thenatural history of a known ureteral calculus demon-strated that 83% of patients will pass their stonewithout the need for intervention.39 One of the moreimportant aspects of this study was the observationthat among the stones that passed spontaneously,95% passed within 6 weeks of followup.

The EAU-AUA Guideline on the Management ofUreteral Calculi suggests as an Option that medicalexpulsive therapy should be considered as first linetreatment for most patients with ureteral stoneswhose symptoms are controlled. As a Standard, theGuidelines recommend that patients “should be fol-lowed with periodic imaging studies to monitorstone position and to assess for hydronephrosis.”4

The Panel sought to validate the reliability ofhydronephrosis as a proxy for the degree of obstruc-tion in patients with suspected ureteral calculi. Inparticular, if hydronephrosis is present with aknown ureteral calculus, what is the best way toassess obstruction or the potential for loss of renalfunction? The majority of these studies used IVP toassess renal obstruction/function (see evidence re-port in Appendix B, available at http://www.auanet.org/content/media/imaging_evidence_report.pdf). Therewas a distinct paucity of studies on the use of nuclearrenography to determine obstruction in this setting.Of note, differences in threshold parameters used toclassify obstruction in these studies contributed tothe variability in the reported sensitivity and spec-ificity.

The quality of the body of evidence regarding thefollowup of a ureteral calculus is low (Level C Evi-dence). The Panel took into account not only thesensitivity/specificity of various imaging modalitiesin determining their ability to follow known ureteralcalculi, but also assessed the impact of radiation ex-posure and costs of the imaging studies when making
their recommendations. Based on these studies and
expert Panel opinion, a decision tree diagram and rec-ommendations are offered (fig. 2).

After a period of MET in a patient with a knownradiopaque ureteral calculus less than 10 mm indiameter with minimal to moderate associated hy-dronephrosis and no evidence of renal damage, as-suming the symptoms are well controlled, the Panelbelieves that ultrasonography combined with plainKUB offers the best combination of sensitivity/spec-ificity with minimal radiation exposure and signifi-cantly reduced cost compared to NCCT imaging. Inpatients who continue to have symptoms without evi-dence of stone passage, the ultrasonography/KUBcombination can assess stone progression as well asongoing hydronephrosis. However, if ultrasonographyand KUB fail to demonstrate hydronephrosis or per-sistent stone, further imaging with plain radiographsor low dose NCCT limited to the area of interest maybe warranted to definitively ascertain the continuedpresence of the stone.

In those patients with a radiolucent stone, lowdose NCCT can assess stone progression and thedegree of hydronephrosis. Clinical acumen combinedwith new findings on imaging studies will assist theclinician in determining whether continued observa-tion combined with MET or surgical intervention iswarranted. It may be reasonable to consider confirma-tory radiographic imaging before surgical interven-tion.

FOLLOWUP URETERAL

CALCULUS AFTER TREATMENT

After definitive surgical intervention for a ureteralcalculus, followup imaging is obtained to assure com-plete stone removal and/or the absence of obstruction.Ureteral instrumentation and particularly stone frag-mentation warrant postoperative imaging to docu-ment 1) the clearance of the stone/fragments, 2) theresolution of hydronephrosis and/or 3) the develop-ment of unanticipated obstruction such as that fromureteral stricture. Although the incidence of ureteralstricture after ureteroscopy is low (1% to 4%), its oc-currence is not entirely predictable.4,40 Ureteral stric-ture formation after SWL is distinctly uncommon (0%to 2%)4,40 and in most reports is likely the result ofadjunctive instrumentation (ureteral catheterization,stone push-back) or stone impaction. However, afterSWL the passage of fragments and resolution of asso-ciated obstruction should be confirmed.

Although the need for an imaging study to con-firm stone/fragment clearance after SWL or ureter-oscopy with lithotripsy is widely accepted, the needfor followup studies in asymptomatic patients toassess for obstruction is subject to debate. At thecenter of the controversy is the reliability with which
symptoms predict obstruction. Weizer et al reviewed
http://www.auanet.org/content/media/imaging_evidence_report.pdf

http://www.auanet.org/content/media/imaging_evidence_report.pdf

eteral


241 patients at a mean of 5.4 months after ureter-oscopy using NCCT, renal ultrasound, IVP, diureticrenography or retrograde pyelogram.40 Of 188 pa-tients with no pain at postoperative followup, 7(3.7%) nonetheless had obstruction on postoperativeimaging studies. Bugg et al also reviewed 118 pa-tients who underwent 143 ureteroscopic procedures,and were evaluated with IVP, renal ultrasound orCT at a mean of 7 months postoperatively.41 Among77 patients with complete followup who weretreated for renal or ureteral calculi, 1 of 25 (4%)without preoperative obstruction who reported res-olution of their symptoms postoperatively was foundto have persistent obstruction. Karadag et al iden-tified silent obstruction in only 1 of 228 asymptom-atic patients (0.4%) in their review of 268 patientsundergoing ureteroscopy for calculi who underwentimaging with IVP at 3 months after ureteroscopy.42

Finally, Karod et al found no cases of silent obstruc-tion among 183 patients who underwent ureteros-copy and were evaluated radiographically at a meanof 73 days postoperatively.43

From these studies, it is clear that the incidenceof postoperative obstruction in asymptomatic pa-

Figure 2. Observation of known ur

tients is decidedly low (Level C Evidence). According

to Bugg et al, among the select group of patientswithout postoperative pain or preoperative obstruc-tion, 25 radiographic studies would be required todiagnose 1 case of persistent obstruction.41 Althoughseemingly a small price to pay to avoid the loss of 1renal unit, this need-to-treat value is hardly justifi-able from a strictly economic viewpoint. Nonethe-less, the Panel believes that the relatively low costand lack of ionizing radiation associated with renalsonography justify its use in the routine followup ofpatients treated for ureteral calculi.40

Obstruction with or without associated symptomsafter ureteroscopy is generally due to obstructingstone fragments or ureteral stricture. With the lowincidence of stricture (less than 1% in most series),obstructing fragments are likely to comprise themore common etiology overall and may be detectablewith KUB if radiopaque, thereby providing a meansto identify patients who require further functionalimaging and/or further treatment. In the future,perhaps with further subgroup analysis, periopera-tive patient or stone characteristics can be identifiedin those patients without obvious persistent stoneswho should undergo a functional imaging study or

calculus (decision tree diagram 2)

renal ultrasound. Based on current data and panel

s afte


opinion, we offer a decision tree diagram for thefollowup of ureteral calculi after treatment withMET or surgical intervention (SWL and ureteros-copy) (fig. 3).

For patients undergoing MET for a ureteral cal-culus in whom there is documented stone passage(stone in hand) and resolution of symptoms, no fur-ther imaging is necessary. If the patient remainssymptomatic despite documented passage, evalua-tion with a renal sonogram will demonstrate whetherpersistent obstruction is present and will indicatethe need for further imaging to identify an addi-tional stone, residual edema or obstruction.

For patients undergoing SWL, followup renalsonogram with KUB for radiopaque stones or with-out KUB for radiolucent stones will document stoneclearance and demonstrate the presence or absenceof hydronephrosis (fig. 3). If the patient is asymp-tomatic and KUB/sonogram shows no stones or hy-dronephrosis, no further imaging is required. If KUB/sonogram demonstrates hydronephrosis and/or residualfragments, further observation with repeat imagingor secondary treatment is indicated. Patients withradiolucent stones and no hydronephrosis who re-main symptomatic and/or have not passed frag-

Figure 3. Followup of ureteral calculu

ments should be further observed with repeat imag-

ing (low dose NCCT) or intervention as indicated(fig. 3).

For patients undergoing ureteroscopy, the decisiontree diagram distinguishes patients who undergo in-tact stone removal from those requiring stone frag-mentation because of differing imaging requirementsto document residual stones. For patients who un-dergo intact stone removal and whose symptoms haveresolved, a renal sonogram is sufficient to documentresolution of hydronephrosis (fig. 4). For symptomaticpatients with or without hydronephrosis or asymp-tomatic patients with hydronephrosis on renal sono-gram, CT of the abdomen and pelvis without andwith contrast will determine the presence and/orsite of obstruction, with further treatment dictatedby the findings.

For patients who underwent ureteroscopy withstone fragmentation and who are asymptomatic, fol-lowup imaging with a sonogram (radiolucent stones)or a sonogram/KUB (radiopaque stones) will docu-ment the presence of residual fragments and/or hy-dronephrosis (fig. 5). In the absence of hydronephro-sis and residual fragments, no further imaging isindicated. However, in patients with radiopaquestones, if residual fragments and/or hydronephrosis

r treatment (decision tree diagram 3)

are documented, further observation or intervention

tractio


is pursued at the discretion of the practitioner. Forpatients with nonopaque stones, hydronephrosis onsonogram should prompt further evaluation withlow dose NCCT to identify obstructing residual frag-ments.

In symptomatic patients with radiopaque stones,a sonogram and KUB also provide sufficient initialimaging to guide the need for further observation,interval imaging or secondary treatment as indi-cated. However, for those with radiolucent stones,low dose NCCT will optimally identify residual frag-ments or obstruction. If either is present, continuedobservation or secondary intervention is dictated bythe severity of symptoms and/or obstruction. In per-sistently symptomatic patients without hydrone-phrosis or residual fragments further managementis left to the discretion of the practitioner based onsuspicion of urinary pathology.

The role of IVP in the followup of patients withureteral calculi who have been treated surgically islimited. However, IVP or diuretic renography maybe used in lieu of CT with contrast in patients who

Figure 4. Followup after ureteroscopic ex

underwent ureteroscopic intact stone removal and

have persistent symptoms or hydronephrosis onsonogram, or in whom additional or residual ure-teral stones are not suspected but there is concernfor obstruction.

Finally, the timing of followup imaging studies orneed for secondary intervention is left to the discre-tion of the treating physician. Since the degree ofhydronephrosis does not correlate predictably withthe degree of obstruction, the level of concern of thepractitioner must dictate the need for and timing offurther functional studies or definitive secondaryintervention.

RISKS AND RESOURCE USE

ASSOCIATED WITH URETERAL IMAGING

The performance characteristics of imaging modali-ties used in the management of ureteral calculousdisease are well documented.5 However, despiteconsensus that NCCT of the abdomen and pelvisprovides the most sensitive and specific informa-tion about the size and location of ureteral cal-

n, intact stone (decision tree diagram 3C)

culi,44,45 the superb performance characteristics of

, requ


CT must be balanced against its potential harmsand costs.

RISKS ASSOCIATED

WITH URETERAL IMAGING

All forms of conventional radiography and CT de-pend on ionizing radiation to create an image. Ion-izing radiation is known to potentially cause harmthrough deterministic and stochastic effects. Deter-ministic effects (eg erythema of the skin and gener-ation of cataracts) occur at a given threshold, andthe effect is proportional to the dose. Stochasticeffects (eg the induction of secondary cancers orhereditary defects) may occur at any dose. Theprobability that a stochastic effect will occur in-creases with the dose, but the severity of the effectis independent of the dose. Deterministic effectsare rarely encountered with diagnostic radiationdoses associated with the management of ureteralcalculous disease.

It is useful to quantify the risk of radiation exposureto patients and health care providers using the conceptof effective dose. Effective dose (in mSv) estimates thepotential adverse biological effect of the sum of theequivalent doses of radiation to exposed organs. There-fore, radiation exposure from various types of diagnos-tic imaging studies can be compared in terms of rela-tive biological risk. Effective dose cannot be equated tothe actual absorbed dose for any individual. The actualabsorbed dose for an individual will depend on thescanning protocol and the equipment used. There iscompelling evidence of wide variability in the effectivedose produced during the same kind of examination(eg CT of the abdomen and pelvis) within an imaging

Figure 5. Followup after ureteroscopic extraction

facility and between imaging facilities.46 Actual doses

in clinical practice may be considerably higher due toseveral factors.46

In addition to the harms associated with radia-tion exposure, imaging studies using IV contrast(iodine or gadolinium) have associated risks. Ad-verse reactions including severe allergic reactions,impaired renal function, nephrogenic systemic fibro-sis and death have been reported.47

MINIMIZING RISKS

All imaging studies using ionizing radiation shouldaspire to the ALARA principle (As Low As Reason-ably Achievable),48 attempting to expose the patientto the least ionizing radiation that will answer theclinical question at hand. Thus, when 2 or moreimaging studies have equal or nearly equal clinicaleffectiveness, the study with the least ionizing radi-ation should be selected. A noncontrast study shouldbe selected over one using contrast when its perfor-mance would be equally effective.

Optimization of selected studies should be pursued.For example, the sensitivity of abdominal ultrasoundor KUB for the detection of a ureteral calculus may beoptimized by withholding food and fluid before theexamination to reduce the adverse effects of bowel gason sensitivity and specificity.49 Similarly, the optimi-zation of conventional radiographs used to identifyureteral calculi may be accomplished by measures todecrease bowel gas, or by adding oblique images ortomograms to reduce missed detection from underly-ing or overlying structures.

Optimization of CT includes limited scanning pro-tocols confined to an anatomical region of interest (egpelvic CT) for evaluation of the distal ureter, adjust-

iring fragmentation (decision tree diagram 3C1)

ments of CT parameters for tissue thickness and body


habitus and limitation of phases (eg noncontrast onlyor combined injection and delayed phases) to reducetotal radiation exposure. Specific protocols to reduceradiation exposure for the detection of ureteral calcu-lous disease have been successful in decreasing theeffective dose of a standard abdominal and pelvic CTfrom 10 to 3 mSv.50

Specific scanning protocols for imaging facilities mayvary significantly based on the wide range of estimates ofeffective dose found in the literature for a given exami-nation. Clinicians will need to understand which scan-ning protocols are being used in imaging their patients.

RESOURCE USE

A study is justified when the benefits of the informa-tion obtained outweigh the potential physical and eco-nomic harms to the patient. Therefore, it is also rea-sonable to consider the cost of an imaging study to theindividual patient and to the health care system.Health care resources are finite. Therefore, cost-effec-tiveness becomes the third factor (along with perfor-mance characteristics and risks) in considering the over-all clinical effectiveness of an imaging study.

COSTS OF IMAGING

The costs of imaging vary widely and are dependent inpart on market related factors and who is responsiblefor payment. One surrogate for relative cost is themaximum allowable charges assigned to the study byCMS (Centers for Medicare & Medicaid Services). Ac-tual charges by imaging providers for each study maybe considerably higher than the CMS allowed charge.By looking at relative charges, it is possible to have asense of cost. For example, NCCT has charges that aretwice as high as ultrasound, while magnetic resonanceimaging charges are threefold higher than CT. How-ever, it is important to keep in mind that charges areartificial and may not correspond proportionately tocost, which reflects the actual cost of the resourcesrequired to provide a given service. In fact, the allow-able charge for CT has been aggressively cut by CMSin an attempt to limit use.

While medical decision making should not becompromised by cost, it is often possible to makerational medical decisions without additional imag-ing studies or with a lower cost option. In those casesin which the information may be obtained by 2equally sensitive or nearly equally sensitive imagingmodalities, the lower cost option should be favored.When a clinical question can be answered equally ornearly equally by 2 or more imaging modalities, themodality with the least harm and lowest overall
resource use should be selected.
SUMMARY

This Technology Assessment has produced clinicaleffectiveness protocols which attempt to summarizeinformation about the 1) performance characteris-tics, 2) risks and 3) costs of imaging studies to pro-vide a rational approach to imaging in the manage-ment of ureteral calculous disease.

ACKNOWLEDGMENTS

James Robert White provided methodological exper-tise and made invaluable contributions to the evi-dence review and analysis. Angela Clark providedproject management and support of the panel.

DISCLAIMER

This document was written by the Imaging PilotPanel of the American Urological Association(AUA) Education and Research, Inc., which wascreated in 2011. The Practice Guidelines Commit-tee of the AUA selected the panel chair. Panelmembers were selected by the chair. Membershipof the panel included urologists with specific ex-pertise in this area. The mission of the committeewas to develop guidance that is analysis-based orconsensus-based, depending on Panel processesand available data, for optimal clinical practicesin the use of imaging for the management of ure-teral calculus.

While this clinical effectiveness protocol does notnecessarily establish the standard of care, AUAseeks to recommend and to encourage compliance bypractitioners with current best practices related tothe condition being treated. As medical knowledgeexpands and technology advances, the documentwill change. Today, this guidance represents notabsolute mandates but provisional proposals fortreatment under the specific conditions described.For all these reasons, this document does not pre-empt physician judgment in individual cases.Treating physicians must consider variations inresources, and patient tolerances, needs, and pref-erences. Conformance with any clinical effective-ness protocol does not guarantee a successful out-come.

Although clinical effectiveness protocols are in-tended to encourage best practices and potentially en-compass available technologies with sufficient data asof close of the literature review, they are necessarilytime-limited. Clinical effectiveness protocols cannotinclude evaluation of all data on emerging technolo-gies or management, including those that are FDA
approved, which may immediately come to represent


accepted clinical practices. For this reason, the AUA
does not regard technologies or management which
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