YMEM 6515 S0196-0644(15)01420-1 10.1016/j.annemergmed.2015.10.021 American College of Emergency Physicians CME Figure 1 Clinically important causes of acute flank pain that require urgent treatment.DVT, Deep venous thrombosis. Figure 2 Algorithm for management of acute unilateral flank pain and suspected ureteral stone. Dashed lines indicate options for the clinician to obtain additional imaging if concerned about clinically important diagnosis. *A strategy with no initial imaging is not based on randomized trial evidence but in my opinion represents reasonable care.POCUS, Point-of-care ultrasound;CT, computed tomography;IVF, intravenous. Figure 3 A, A curved ultrasonographic probe is placed in the flank in the coronal plane to produce an image of the long axis of the kidney. Inspect the renal pelvis for hydronephrosis.B, Longitudinal axis view of the kidney, with a clear view of the renal pelvis, marked with a white arrow. There is no appearance of hydronephrosis to indicate an obstructing stone.C, Longitudinal axis view of the kidney with mild to moderate hydronephrosis, marked with a white arrow.D, Transverse view of the bladder, with an ureterovesicular junction stone visible. Shadowing is present. Editor's Note:The Expert Clinical Management series consists of shorter, practical review articles focused on the optimal approach to a specific sign, symptom, disease, procedure, technology, or other emergency department challenge. These articles-typically solicited from recognized experts in the subject area-will summarize the best available evidence relating to the topic while including practical recommendations where the evidence is incomplete or conflicting. Supervising editor:Steven M. Green, MD Funding and support:ByAnnalspolicy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (seewww.icmje.org). The author has stated that no such relationships exist and provided the following details: This study was supported by funding from theAgency for Healthcare Research and Quality(grantK08 HS02181) andNational Center for Advancing Translational Sciences(grant8KL2 TR000143-08). Dr. Callaham has recused himself from the decisionmaking for this article. Apodcast for this article is available atwww.annemergmed.com. Continuing Medical Educationexam for this article is available athttp://www.acep.org/ACEPeCME/. General medicine/expert clinical management Managing Urolithiasis Ralph C. Wang MD * ralph.wang@ucsf.edu http://twitter.com/ralphcwang Department of Emergency Medicine, University of California, San Francisco, San Francisco, CA Department of Emergency Medicine University of California San Francisco, San Francisco CA * Corresponding Author. SEE EDITORIAL, P. 433 . Introduction Urolithiasis is a common disease, estimated to affect 11% of men and 7% of women in their lifetime.1 Ureteral stones can cause acute unilateral flank pain radiating to the groin, often accompanied by nausea, vomiting, and urinary symptoms.2 More than 1 million patients with suspected urolithiasis present to an emergency department (ED) each year in the United States.3 This review will describe ED evaluation, therapies, and the identification of patients who require urgent urologic intervention, with recommendations based on clinical trials; on guidelines from the American College of Emergency Physicians (ACEP), American College of Radiology, and American Urologic Association; and on anecdotal experience. Goals of the Evaluation When ureteral stone is suspected, our foremost goal is to identify those patients who require urgent, and in some cases, emergency treatment, either for important alternative diagnoses (eg, appendicitis, cholecystitis, ovarian torsion)4 or "stone-related emergencies" (Figure 1).2,5 Approximately 10% of ED patients with suspected urolithiasis are admitted,6-8 with prospective research identifying a 3.7% and 5.3% prevalence of important alternative diagnoses.8,9 Our secondary goal of confirming the presence of urolithiasis is of lesser importance because patients with an uncomplicated stone are almost always managed expectantly. Risk Assessment for Clinically Important Diagnoses Ureterolithiasis causes severe unilateral colicky flank pain, and patients usually present soon (within hours) of onset. The pain may radiate from the flank anteromedially toward the groin into the genitals and may be accompanied by nausea, vomiting, and hematuria.2,8 Lower urinary tract symptoms such as dysuria and urgency suggest distal ureteral stones. The classic appearance is that of a patient in distress, unable to find a position of comfort. Vital signs are often normal. Atypical clinical features such as hypotension or abnormalities on abdominal, testicular, or pelvic examination suggest alternative diagnoses. Complicated urolithiasis should be suspected if there is persistent pain, vomiting, fever, pyuria, elevated creatinine level, anuria, or a history of a solitary or transplanted kidney. A history of urolithiasis decreases the risk of important alternative diagnosis.10 Although hematuria is common in urolithiasis, it does not by itself exclude or reliably identify the diagnosis, with reported sensitivities ranging from 71% to 95% and specificities ranging from 18% to 49% for urolithiasis.11-13 A positive pregnancy test result should lead to consideration of ectopic pregnancy as a cause of pain and also limits the choice of imaging to ultrasonography. With urolithiasis, the absence of pyuria cannot exclude a complicating urinary tract infection, with a reported sensitivity and specificity of 86% and 79%, respectively.14 Accordingly, stone patients at higher risk (female patients and those with pyuria or urinary tract infection symptoms) should receive a urine culture.14 Selection of Appropriate Imaging The need for and type of imaging vary with underlying risk of important alternative diagnosis, ureteral stone, or a stone-related emergency (Figure 2). Emergency physicians should use clinical judgment to make this assessment. The STONE score is a clinical decision rule that sorts patients with suspected ureterolithiasis into low-, moderate-, and high-risk groups, with those with a high score in the original study having an 89% probability of a stone and a 1.6% probability of alternative diagnosis.8 In an external validation, the sensitivity and specificity of a high score were 53% and 87%, with a 1.2% probability of important alternative diagnosis (upper 95% confidence interval of 3.6%).9 Thus, the STONE score alone cannot rule in or rule out stones or exclude clinically important diagnoses. Its role for imaging decisions remains undefined but has the potential to be used as part of an algorithm for suspected urolithiasis. Moderate to High Risk of a Clinically Important Diagnosis Patients at moderate or high risk of a stone emergency or a clinically important alternative diagnosis should receive an unenhanced computed tomography (CT) scan. The accuracy of CT scan for ureteral stones is excellent, and CT scan can identify hydronephrosis, characterize stone size and location, and detect important alternative diagnoses.15-18 The American College of Radiology gives their highest appropriateness rating for CT in patients with first-time acute flank pain,19 and 70% of patients who received a diagnosis of urolithiasis received a CT scan in 2007.3 Despite this, routine CT does not appear to improve outcomes. A national survey found no change in the diagnosis of kidney stone, alternative diagnoses, or hospitalization despite a 10-fold increase in CT use between 1995 and 2007.20 The ability of CT to characterize stone size and location at the initial ED visit is not routinely necessary, and this imaging increases costs, incidental findings, length of stay, and the risk of subsequent cancer.21-23 Thus, CT should be reserved for patients who would most benefit by increasing diagnostic certainty for clinically important diagnoses or experience less harm from radiation exposure. ACEP recommends avoiding CT scan in patients younger than 50 years and with a history of kidney stones presenting with recurrent symptoms. There is promise for reduced-dose CT scan protocols.24,25 Low Risk of a Clinically Important Diagnosis Patients at low risk of a stone emergency or a clinically important alternative diagnosis should receive ultrasonography, performed by either an emergency physician or the radiology department. Ultrasonography is less sensitive (24% to 57%) than CT for the identification of ureteral stone, especially small stones, and missed occasional occurrences of hydronephrosis in older studies, perhaps in dehydrated patients.26-28 In a more recent prospective study, it was shown to accurately identify hydronephrosis (Figure 3).28,29 Ultrasonography is first line for a number of important alternative diagnoses, such as cholecystitis and ovarian torsion, and is an acceptable initial test in appendicitis and aortic aneurysm. ACEP has identified urinary tract point-of-care ultrasonography as a core application since 2001.30 Its main limitation is operator skill; fellowship-trained emergency physicians have excellent sensitivity and good specificity for hydronephrosis, whereas those without fellowship training have modest accuracy.31 In a multicenter randomized trial of point-of-care ultrasonography versus radiology ultrasonography versus CT scan, there was no significant difference in missed serious diagnosis or adverse events.7 A CT scan may be obtained if the clinician is still uncertain about the presence of a clinically important diagnosis after ultrasonography; in the randomized trial, 25% of patients in the radiology ultrasonography arm and 40% of those in the point-of-care ultrasonography arm ultimately received a CT scan.7 Ultrasonography is preferred in patients at highest risk for complications fromionizing radiation (pregnant or pediatric patients) or who are less likely to benefit from CT (history of kidney stones).19 Very Low Risk of a Clinically Important Diagnosis In my opinion, well-appearing, afebrile patients with mild or transient symptoms could receive ultrasonography or instead be discharged without imaging, with a plan to return for persistent or worsening symptoms. In a national survey of ED imaging in 2005 to 2007, approximately half of patients with suspected urolithiasis did not receive either ultrasonography or CT.20 These may have been patients who had an alternative diagnosis that did not require imaging (such as pyelonephritis or low back pain) or had transient or straightforward renal colic. Treatment of Ureteral Stone Pain relief. Provide analgesia, antiemetics, and intravenous hydration as needed at the evaluation. Nonsteroidal anti-inflammatories (eg, ketorolac 15 to 30 mg intravenously) can provide effective analgesia,32 with opioids administered either concurrently for rapid relief or if the nonsteroidal anti-inflammatory effect is insufficient. Use oral nonsteroidal anti-inflammatories with or without opioids for patients who are less symptomatic or for analgesia after discharge. Intravenous hydration will benefit patients who are dehydrated or have been unable to drink as a result of vomiting; however, this use of such fluids to "flush out" a stone has not been shown to improve clinical outcomes.33 Patient Disposition Patients at risk for a stone-related emergency should be admitted and receive urology consultation (Figure 1). When an obstructing stone is accompanied by sepsis, the urinary collecting system should be decompressed as quickly as possible.5 Given the limitations of pyuria for the diagnosis,14 patients with a suspected urinary tract infection in the absence of hydronephrosis, fever, or ill appearance could be discharged with oral antibiotic treatment, a urine culture, and close follow-up.5 Among patients receiving a diagnosis of urolithiasis, 20% are admitted.7,20,34 Expectant Management for Stone Passage Patients with urolithiasis and no indications for urgent intervention can be discharged home with a plan of observation for spontaneous stone passage. Large and proximally located stones are less likely to pass spontaneously; stones less than 5 mm and 5 to 10 mm have been noted to pass in 68% and 47% of cases, respectively.35,36 Urologists typically offer ureteroscopy or shock wave lithotripsy to patients with retained stones and persistent symptoms.5 The American Urologic Association recommends urology consultation for stones greater than 10 mm and medical expulsive therapy (most commonly tamsulosin) for smaller stones.5 Tamsulosin was reported as effective in enhancing stone passage in a recent Cochrane review of 28 randomized controlled trials (risk ratio 1.5; 95% confidence interval 1.3 to 1.6).37 Two subsequent multicenter randomized trials have yielded conflicting results; one found no benefit, and one restricted to distal stones noted benefit in patients with larger stones (>5 mm).38,39 Given that larger stones are less likely to spontaneously pass, it seems logical that these patients may actually benefit more from tamsulosin.35,39 The principal adverse effect of these alpha-blockers is orthostatic hypotension (number needed to harm 19), although in most studies this did not require cessation of therapy.37 Dosing just before bedtime can mitigate the risk. Despite conflicting results between the Cochrane review and the trial with negative results, I believe currently the preponderance of the evidence suggests a benefit, and I would provide tamsulosin to patients who received a diagnosis of a ureteral stone. Finally, patients who receive a diagnosis of a ureteral stone should be instructed to follow up with a urologist and given appropriate instructions to return for worsening symptoms. References 1 C.D. Scales A.C. Smith J.M. Hanley Project Urologic Diseases of America Project Prevalence of kidney stones in the United States Eur Urol 62 2012 160 165 2 J.M.H. Teichman Clinical practice. Acute renal colic from ureteral calculus N Engl J Med 350 2004 684 693 3 C.-W. Fwu P.W. Eggers P.L. Kimmel Emergency department visits, use of imaging, and drugs for urolithiasis have increased in the United States Kidney Int 83 2013 479 486 4 C.L. Moore B. Daniels D. Singh Prevalence and clinical importance of alternative causes of symptoms using a renal colic computed tomography protocol in patients with flank or back pain and absence of pyuria Acad Emerg Med 20 2013 470 478 5 G.M. Preminger H.-G. Tiselius D.G. Assimos 2007 Guideline for the management of ureteral calculi J Urol 178 2007 2418 2434 6 A.C.H.R. Westphalen J. Maselli R.C. Wang Radiological imaging of patients with suspected urinary tract stones: national trends, diagnoses, and predictors Acad Emerg Med 18 2011 699 707 7 R. Smith-Bindman C. Aubin J. Bailitz Ultrasonography versus computed tomography for suspected nephrolithiasis N Engl J Med 371 2014 1100 1110 8 C.L. Moore S. Bomann B. Daniels Derivation and validation of a clinical prediction rule for uncomplicated ureteral stone-the STONE score: retrospective and prospective observational cohort studies BMJ 348 2014 g2191 9 R.C. Wang R.M Rodriguez M. Moghadassi External validation of the STONE score, a clinical prediction rule for ureteral stone: an observational multi-institutional study Ann Emerg Med 67 2016 423 432 10 A. Goldstone A. Bushnell Does diagnosis change as a result of repeat renal colic computed tomography scan in patients with a history of kidney stones? Am J Emerg Med 28 2010 291 295 11 T. Kobayashi K. Nishizawa J. Watanabe Clinical characteristics of ureteral calculi detected by nonenhanced computerized tomography after unclear results of plain radiography and ultrasonography J Urol 170 2003 799 802 12 P. Bove D. Kaplan N. Dalrymple Reexamining the value of hematuria testing in patients with acute flank pain J Urol 162 3 pt 1 1999 685 687 13 J.S. Luchs D.S. Katz M.J. Lane Utility of hematuria testing in patients with suspected renal colic: correlation with unenhanced helical CT results Urology 59 2002 839 842 14 F.M. Abrahamian A. Krishnadasan W.R. Mower Association of pyuria and clinical characteristics with the presence of urinary tract infection among patients with acute nephrolithiasis Ann Emerg Med 62 2013 526 533 15 R.C. Smith M. Verga S. McCarthy Diagnosis of acute flank pain: value of unenhanced helical CT AJR Am J Roentgenol 166 1996 97 101 16 N.C. Dalrymple M. Verga K.R. Anderson The value of unenhanced helical computerized tomography in the management of acute flank pain J Urol 159 1998 735 740 17 R.C. Smith M. Verga N. Dalrymple Acute ureteral obstruction: value of secondary signs of helical unenhanced CT AJR Am J Roentgenol 167 2012 1109 1113 18 H. Hoppe R. Studer T.M. Kessler Alternate or additional findings to stone disease on unenhanced computerized tomography for acute flank pain can impact management J Urol 175 2006 1725 1730 19 P. Fritzsche E.S. Amis Jr. L.R. Bigongiari Acute onset flank pain, suspicion of stone disease. American College of Radiology. ACR Appropriateness Criteria Radiology 215 2000 683 20 A.C. Westphalen R.Y. Hsia J.H. Maselli Radiological imaging of patients with suspected urinary tract stones: national trends, diagnoses, and predictors Acad Emerg Med 18 2011 699 707 21 R. Smith-Bindman J. Lipson R. Marcus Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer Arch Intern Med 169 2009 2078 22 R. Smith-Bindman D.L. Miglioretti E. Johnson Use of diagnostic imaging studies and associated radiation exposure for patients enrolled in large integrated health care systems, 1996-2010 JAMA 307 2012 2400 2409 23 R. Smith-Bindman D.L. Miglioretti E.B. Larson Rising use of diagnostic medical imaging in a large integrated health system Health Aff (Millwood) 27 2008 1491 1502 24 C.L. Moore B. Daniels M. Ghita Accuracy of reduced-dose computed tomography for ureteral stones in emergency department patients Ann Emerg Med 65 2015 189 198.e182 25 R. Smith-Bindman M. 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Daniels Effect of provider experience on clinician-performed ultrasonography for hydronephrosis in patients with suspected renal colic Ann Emerg Med 64 2014 269 276 32 A. Holdgate T. Pollock Systematic review of the relative efficacy of non-steroidal anti-inflammatory drugs and opioids in the treatment of acute renal colic BMJ 328 2004 1401 33 A.S. Worster W. Bhanich Supapol Fluids and diuretics for acute ureteric colic Cochrane Database Syst Rev 2 2012 CD004926 34 Foster G, Stocks C, Borofsky MS. Statistical brief #139. Agency of Healthcare Research and Quality Report. 2012:1-10. 35 D.M. Coll M.J. Varanelli R.C. Smith Relationship of spontaneous passage of ureteral calculi to stone size and location as revealed by unenhanced helical CT AJR Am J Roentgenol 178 2002 101 103 36 L. Papa I.G. Stiell G.A. Wells Predicting intervention in renal colic patients afteremergency department evaluation CJEM 7 2005 78 86 37 T. Campschroer Y. Zhu D. 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