Diagnostic Imaging Pathways - Loin Pain (Renal Colic)
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This pathway provides guidance on the investigation of adult patients with renal colic, including those presenting for the first time and those with recurrent symptoms.
Date reviewed: September 2015
Date of next review: 2017/2018
Published: February 2016
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The relative radiation level (RRL) of each imaging investigation is displayed in the pop up box.
| SYMBOL | RRL | EFFECTIVE DOSE RANGE |
 | None | 0 |
 | Minimal | < 1 millisieverts |
 | Low | 1-5 mSv |
 | Medium | 5-10 mSv |
 | High | >10 mSv |
Images
Image GalleryNote: These images open in a new page | ||
|---|---|---|
| 1 |  |
Urolithiasis Image 1 (Plain Radiography of Kidneys, Ureter, Bladder - KUB): An opacity is present (arrow) at the left vesico-ureteric junction. |
| 2 |  |
Pelvicalyceal Dilatation Image 2 (Intravenous Pyelography): No stone is visualised, but there is dilatation of the ureter and pelvicalyceal system on the left side. |
| 3 |  |
Staghorn Calculus Image 3 (KUB): A staghorn calculus is present in the collecting system of the right kidney. |
| 4a |  |
Urolithiasis Image 4a and b (Computed Tomography): A 10mm calculus is present at the left pelviureteric junction responsible for mild left hydronephrosis and perinephric stranding. |
| 4b |  |
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Teaching Points
Teaching Points
- Non-enhanced CT is the ‘gold-standard’ for diagnosis of ureteric colic
- Low-dose CT protocols can be effectively used in acute renal colic
- Immediate imaging is required when patients do not improve after treatment and / or when there is fever and / or leukocytosis and / or the patient has renal failure or a single kidney
- However, because of concerns about ionising radiation and because the vast majority of ureteric stones pass without the need for intervention, ultrasound (US) has been increasingly recommended and used as the initial imaging modality, with no sacrifice in patient outcome, thus avoiding the need for CT in about 70% of cases
- Ultrasound is also capable of identifying most of the alternative diagnoses listed as mimickers of renal colic
- US in combination with plain x-ray KUB misses very few clinically important stones
- In pregnant patients, it should be borne in mind that unless a calculus is visualized it may be difficult to differentiate obstructive hydronephrosis due to a calculus from ‘physiological’ hydronephrosis of pregnancy. In selected cases, MRI urography may be then required
- Conventional IVP can now be considered almost obsolete for the diagnosis of renal colic
lr
Loin Pain (Renal Colic)
- Non-enhanced CT is the ‘gold-standard’ for diagnosis of ureteric colic and is used in many institutions. However, despite the introduction of low-dose CT protocols, because many patients are young and have recurrent episodes of renal colic, there is concern about cumulative radiation dose. Therefore, ultrasound (US) has been increasingly recommended and used as the initial imaging modality, with no sacrifice in patient outcome, thus avoiding the need for CT in about 70% of cases. 1 Despite the superior sensitivity of CT versus US, the outcome is the same whether CT or US is used for imaging 2
- Recent European Association of Urology Guidelines on urolithiasis recommend US as the primary imaging modality, 3 quoting a sensitivity of 45% and specificity of 94% for ureteric stones 4
- Because young patients with typical symptoms of renal colic have a low incidence of adverse outcomes, there is a valid argument for avoiding acute imaging altogether, and deferring investigating only if symptoms persist or the stone has not been known to pass
- Immediate imaging is required when patients do not improve after treatment and / or when there is fever and / or leukocytosis and / or the patient has renal failure or a single kidney
- Predictors for spontaneous passage of ureteric stones include
- Stone size - the large majority of stones <4-5 mm pass spontaneously
- Stone location - patients who present with stones in the distal ureter have a higher chance of spontaneous passage
- One group of investigators have found that increased concentrations of serum WBCs and neutrophils at the time of the acute phase of a renal colic to be associated with increased likelihood of spontaneous passage 5
- It should additionally be noted that US is also capable of identifying most of the alternative diagnoses listed as mimickers of renal colic
us
Ultrasound (US) Urinary Tracts
- CT is the gold-standard’ for diagnosis of ureteric calculi
- However, because
- Of concerns about ionising radiation in this cohort of patients who have a high incidence of recurrent disease
- The vast majority of ureteric stones pass without the need for intervention
- CT in the emergency department rarely alters immediate management 6,7
- There is a trend towards a more discriminate use of CT of the kidneys, ureters and urinary bladder (KUB) in patients with clinical uncomplicated acute renal colic, particularly in young female patients, in whom there is a relatively high incidence of negative CT examinations, and in whom radiation is more of an issue 8,9
- Adverse events are rare among patients <50 years old with flank pain when CT was not required according to the clinical assessment of the Emergency Physician 10
- Therefore, it has been suggested by several authors, including the European Association of Urology 3 that ultrasound (US) should be considered the primary imaging technique. It is a reproducible, non-invasive and non-expensive imaging technique, achieving accurate diagnosis in most cases without the need for radiation 1
- A recent study comparing ‘point-of-care’ US, US performed in the radiology department and CT showed that initial US was associated with lower cumulative ionising radiation doses but no other significant difference in outcomes. 2 It is therefore, apparent that despite the inferior sensitivity of US, the outcome is the same whether CT or US is used for imaging
- The US diagnosis of ureteric colic is based on the following findings
- Visualization of calculi. The sensitivity of US for the detection of ureteral stones varies according to stone size and location, with reported sensitivities being very variable - usually in the range of 60-90% plus. 4,11,12,13 Mid-ureteric calculi are particularly difficult to visualize on US. However, specificity of US for detecting ureteric calculi is 94-100% 3,13
- Indirect findings
- Hydronephrosis
- Asymmetry or absence of ureteric jet
- Increased Resistive Index in affected kidney
- Colour Doppler ‘twinkling’ artifact Incorporating these indirect findings in to the analysis significantly increases the sensitivity of US 13
- Stones missed on ultrasound however, are typically small (<5 mm) and pass spontaneously 14,15
ct_kub
Computed Tomography of the Kidneys, Ureters and Urinary Bladder (CT KUB)
- Unenhanced (i.e. no IV contrast) CT scan - so called CT KUB or NCCT is the most accurate and widely used imaging investigation for diagnosis of ureteric stones. However, despite the superior sensitivity of CT versus ultrasound (US), the outcome is the same whether CT or US is used for imaging 2
- CT can identify the presence of stones with very high accuracy (>95%), 16 allows accurate measurement of stones ( the major factor in determining whether stones will pass without intervention) and, to some extent, stone composition. CT is also able to identify alternative diagnoses that can mimic renal colic in up to 10% of cases, 17 e.g.
- Pyelonephritis
- Acute adnexal pathology in women
- Appendicitis
- Diverticulitis
- Abdominal aortic aneurysm rupture or aortic dissection
- Colonic diverticulitis
- However, it should be noted that US is also capable of identifying most of the alternative diagnoses listed as mimickers of renal colic
- Studies using "low-dose" protocols have shown sensitivities of 93-97% and specificities of 86-97%, when compared to standard dose CT, 18 and radiation doses equal to or lower than that of intravenous pyelogram (IVP). 18,19,20 More recent studies confirm the accuracy of low dose protocols in patients with a BMI<30; low-dose CT was 86% sensitive for detecting ureteral calculi <3 mm and 100% sensitive for detecting calculi >3 mm. 21 These low-dose protocols can be effectively used in acute renal colic. 22,23 In addition, alternative diagnoses mimicking renal colic can be diagnosed. 17,24 Two studies demonstrated no difference in detecting alternative or additional pathology between "low-dose" and "standard dose" protocols 18,25
- Some studies have reported ultra-low dose CT protocols with doses comparable to one plain KUB film with persisting high accuracy 16 allows accurate measurement of stones ( the major factor in determining whether stones will pass without intervention) and, to some extent, stone composition. CT is also able to identify alternative diagnoses that can mimic renal colic in up to 10% of cases 19,26
- For patients with BMI >30, discretionary increase in CT exposure parameters may be needed
- Earlier studies using "low-dose" multidetector CT (MDCT) protocols reported increased rates of false positive and false negative results in obese patients. 18,20 More recent studies have not reported similar difficulties 19,25
- Despite the above, the adoption of low-dose protocols has not been universal 27
- However, there is concern regarding cumulative dose from repeated studies required for follow-up of calculi, or in patients with recurrent stones 28,29 although this is much less of an issue if low-dose protocols are employed
- There is a trend towards a more discriminate use of CT KUB in patients with clinical uncomplicated acute renal colic, particularly in young female patients, in whom there is a relatively high incidence of negative CT examinations, and in whom radiation is more of an issue 8,9
- Of the issue of ionising radiation
- The vast majority of ureteric stones pass without the need for intervention
- CT in the emergency department rarely alters immediate management 6,7
- Adverse events are rare among patients <50 years old with flank pain when CT was not required according to the clinical assessment of the Emergency Physician 10
- Therefore, it has been recommended that US should be considered as the primary imaging technique. 3 It is a reproducible, non-invasive and non-expensive imaging technique, achieving accurate diagnosis in most cases without the need for radiation. 1 Stones missed on ultrasound, are typically small (<5 mm) and pass spontaneously 14,15
- However, the EAU guidelines also recommend that a positive US be followed by a non-contrast CT scan to “confirm diagnosis” and to assess stone diameter and density. Given that the large majority of stones pass spontaneously, this would appear to be over-investigation in most patients. It would be sensible to reserve CT in US positive patients for those in whom intervention is contemplated
- The recent use of dual-energy CT increases the ability to characterize all ureteral calculi, discriminating uric acid stones from calcium salt stones. 30,31,32,33 However, this technique is not yet widely available
- US in combination with plain x-ray KUB misses very few clinically important stones 34
- Conventional IVP can now be considered almost obsolete for the diagnosis of renal colic
xkub
Plain Radiography of the Kidneys, Ureters and Bladder (Plain X-ray KUB)
- The role of plain radiography (KUB) is as follows
- Sensitivity of 44-77% and specificity of 80-87% for detecting ureteric calculi 3
- Identifies radiopaque stones which are usually calcium-containing, struvite and cystine stones. Uric acid stones however, are usually radiolucent and are unlikely to be detected
- This will enable the progress of the stone to be followed using plain radiography alone
pgts
Pregnant Patients
- Ultrasound (US) is the first investigation of choice as it does not involve exposure to ionising radiation. However, it should be borne in mind that unless a calculus is visualized it may be difficult to differentiate obstructive hydronephrosis due to a calculus from ‘physiological’ hydronephrosis of pregnancy. In selected cases, MRI urography may be required 37
References
References
Date of literature search: September 2015
The search methodology is available on request. Email
References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document
- Nicolau C, Claudon M, Derchi LE, Adam EJ, Nielsen MB, Mostbeck G, et al. Imaging patients with renal colic-consider ultrasound first. Insights Imaging. 2015;6(4):441-7. (Review article). View the reference
- Smith-Bindman R, Aubin C, Bailitz J, Bengiamin RN, Camargo CA, Jr., Corbo J, et al. Ultrasonography versus computed tomography for suspected nephrolithiasis. N Engl J Med. 2014;371(12):1100-10. (Level II evidence). View the reference
- Turk C, Petrik A, Sarica K, Seitz C, Skolarikos A, Straub M, et al. EAU guidelines on diagnosis and conservative management of urolithiasis. Eur Urol. 2015:pii: S0302-2838(15)00699-5. [Epub ahead of print]. (Guidelines). View the reference
- Ray AA, Ghiculete D, Pace KT, Honey RJ. Limitations to ultrasound in the detection and measurement of urinary tract calculi. Urology. 2010;76(2):295-300. (Level III evidence). View the reference
- Sfoungaristos S, Kavouras A, Katafigiotis I, Perimenis P. Role of white blood cell and neutrophil counts in predicting spontaneous stone passage in patients with renal colic. BJU Int. 2012;110(8 Pt B):E339-45. (Level III evidence). View the reference
- Lindqvist K, Hellstrom M, Holmberg G, Peeker R, Grenabo L. Immediate versus deferred radiological investigation after acute renal colic: a prospective randomized study. Scand J Urol Nephrol. 2006;40(2):119-24. (Level II evidence). View the reference
- Zwank MD, Ho BM, Gresback D, Stuck LH, Salzman JG, Woster WR. Does computed tomographic scan affect diagnosis and management of patients with suspected renal colic? Am J Emerg Med. 2014;32(4):367-70. (Level III evidence). View the reference
- Patatas K, Panditaratne N, Wah TM, Weston MJ, Irving HC. Emergency department imaging protocol for suspected acute renal colic: re-evaluating our service. Br J Radiol. 2012;85(1016):1118-22. (Level III evidence). View the reference
- Aubrey-Bassler FK, Lee SD, Barter RB, Asghari S, Cullen R, Godwin M. Utility of computed tomography and derivation and validation of a score to identify an emergent outcome in 2,315 patients with suspected urinary tract stone. CJEM. 2013;15(5):261-9. (Level III evidence). View the reference
- Epstein N, Rosenberg P, Samuel M, Lee J. Adverse events are rare among adults 50 years of age and younger with flank pain when abdominal computed tomography is not clinically indicated according to the emergency physician. CJEM. 2013;15(3):167-74. (Level III/IV evidence). View the reference
- Ripolles T, Martinez-Perez MJ, Vizuete J, Miralles S, Delgado F, Pastor-Navarro T. Sonographic diagnosis of symptomatic ureteral calculi: usefulness of the twinkling artifact. Abdom Imaging. 2013;38(4):863-9. (Level III evidence). View the reference
- Patlas M, Farkas A, Fisher D, Zaghal I, Hadas-Halpern I. Ultrasound vs CT for the detection of ureteric stones in patients with renal colic. Br J Radiol. 2001;74(886):901-4. (Level III evidence). View the reference
- Sheafor DH, Hertzberg BS, Freed KS, Carroll BA, Keogan MT, Paulson EK, et al. Nonenhanced helical CT and US in the emergency evaluation of patients with renal colic: prospective comparison. Radiology. 2000;217(3):792-7. (Level III evidence). View the reference
- Ripolles T, Agramunt M, Errando J, Martinez MJ, Coronel B, Morales M. Suspected ureteral colic: plain film and sonography vs unenhanced helical CT. A prospective study in 66 patients. Eur Radiol. 2004;14(1):129-36. (Level III evidence). View the reference
- Catalano O, Nunziata A, Altei F, Siani A. Suspected ureteral colic: primary helical CT versus selective helical CT after unenhanced radiography and sonography. AJR Am J Roentgenol. 2002;178(2):379-87. (Level II evidence). View the reference
- Smith RC, Verga M, McCarthy S, Rosenfield AT. Diagnosis of acute flank pain: value of unenhanced helical CT. Am J Roentgenol. 1996;166:97-101. (Level II/III evidence). View the reference
- Pernet J, Abergel S, Parra J, Ayed A, Bokobza J, Renard-Penna R, et al. Prevalence of alternative diagnoses in patients with suspected uncomplicated renal colic undergoing computed tomography: a prospective study. CJEM. 2015;17(1):67-73. (Level III evidence). View the reference
- Tack D, Sourtzis S, Delpierre I, de Maertelaer V, Gevenois PA. Low-dose unenhanced multidetector CT of patients with suspected renal colic. AJR Am J Roentgenol. 2003;180(2):305-11. (Level II/III evidence). View the reference
- Kluner C, Hein PA, Gralla O, Hein E, Hamm B, Romano V, et al. Does ultra-low-dose CT with a radiation dose equivalent to that of KUB suffice to detect renal and ureteral calculi? J Comput Assist Tomogr. 2006;30(1):44-50. (Level II/III evidence). View the reference
- Hamm M, Knopfle E, Wartenberg S, Wawroschek F, Weckermann D, Harzmann R. Low dose unenhanced helical computerized tomography for the evaluation of acute flank pain. J Urol. 2002;167(4):1687-91. (Level II/III evidence). View the reference
- Poletti PA, Platon A, Rutschmann OT, Schmidlin FR, Iselin CE, Becker CD. Low-dose versus standard-dose CT protocol in patients with clinically suspected renal colic. AJR Am J Roentgenol. 2007;188(4):927-33. (Level III evidence). View the reference
- Jain N, Robinson S. Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. BET 4: Investigating flank pain: can the CT stay low? Emerg Med J. 2012;29(8):687-8. (Review article). View the reference
- Fulgham PF, Assimos DG, Pearle MS, Preminger GM. A clinical effectiveness protocols for imaging in the management of ureteral calculous disease: AUA technology assessment. J Urol. 2013;189(4):1203-13. (Review article). View the reference
- Moore CL, Daniels B, Singh D, Luty S, Molinaro A. 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. 2013;20(5):470-8. (Level III evidence). View the reference
- Kim BS, Hwang IK, Choi YW, Namkung S, Kim HC, Hwang WC, et al. Low-dose and standard-dose unenhanced helical computed tomography for the assessment of acute renal colic: prospective comparative study. Acta Radiol. 2005;46(7):756-63. (Level III evidence). View the reference
- McLaughlin PD, Murphy KP, Hayes SA, Carey K, Sammon J, Crush L, et al. Non-contrast CT at comparable dose to an abdominal radiograph in patients with acute renal colic; impact of iterative reconstruction on image quality and diagnostic performance. Insights Imaging. 2014;5(2):217-30. (Level III evidence). View the reference
- Lukasiewicz A, Bhargavan-Chatfield M, Coombs L, Ghita M, Weinreb J, Gunabushanam G, et al. Radiation dose index of renal colic protocol CT studies in the United States: a report from the American College of Radiology National Radiology Data Registry. Radiology. 2014;271(2):445-51. (Level III evidence). View the reference
- Manohar P, McCahy P. Repeated radiological radiation exposure in patients undergoing surgery for urinary tract stone disease in Victoria, Australia. BJU Int. 2011;108 Suppl 2:34-7. (Level III evidence). View the reference
- Katz SI, Saluja S, Brink JA, Forman HP. Radiation dose associated with unenhanced CT for suspected renal colic: impact of repetitive studies. AJR Am J Roentgenol. 2006;186(4):1120-4. (Level III evidence). View the reference
- Ascenti G, Siragusa C, Racchiusa S, Ielo I, Privitera G, Midili F, et al. Stone-targeted dual-energy CT: a new diagnostic approach to urinary calculosis. AJR Am J Roentgenol. 2010;195(4):953-8. (Level III evidence). View the reference
- Boll DT, Patil NA, Paulson EK, Merkle EM, Simmons WN, Pierre SA, et al. Renal stone assessment with dual-energy multidetector CT and advanced postprocessing techniques: improved characterization of renal stone composition--pilot study. Radiology. 2009;250(3):813-20. (Level III evidence). View the reference
- Grosjean R, Sauer B, Guerra RM, Daudon M, Blum A, Felblinger J, et al. Characterization of human renal stones with MDCT: advantage of dual energy and limitations due to respiratory motion. AJR Am J Roentgenol. 2008;190(3):720-8. (Level III evidence). View the reference
- Thomas C, Heuschmid M, Schilling D, Ketelsen D, Tsiflikas I, Stenzl A, et al. Urinary calculi composed of uric acid, cystine, and mineral salts: differentiation with dual-energy CT at a radiation dose comparable to that of intravenous pyelography. Radiology. 2010;257(2):402-9. (Level IV evidence). View the reference
- Ekici S, Sinanoglu O. Comparison of conventional radiography combined with ultrasonography versus nonenhanced helical computed tomography in evaluation of patients with renal colic. Urol Res. 2012;40(5):543-7. (Level III evidence). View the reference
- Foell K, Ordon M, Ghiculete D, Lee JY, Honey RJ, Pace KT. Does baseline radiography of the kidneys, ureters, and bladder help facilitate stone management in patients presenting to the emergency department with renal colic? Endourol. 2013;27(12):1425-30. (Level III evidence). View the reference
- Teichman JM. Clinical practice. Acute renal colic from ureteral calculus. N Engl J Med. 2004;350(7):684-93. (Review article). View the reference
- Masselli G, Derme M, Laghi F, Polettini E, Brunelli R, Framarino ML, et al. Imaging of stone disease in pregnancy. Abdom Imaging. 2013;38(6):1409-14. (Review article). View the reference
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