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Pyelonephritis
Sara M. O'Hara, MD, FAAP
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KEY FACTS

  • Terminology

    • Imaging

      • Clinical Issues

        TERMINOLOGY

        • Synonyms

          • Acute lobar nephronia, focal bacterial nephritis
        • Definitions

          • Acute infection of renal parenchyma
          • Overview
            • Classic imaging appearance: Focal swelling & ↓ perfusion of affected parenchyma visible on nuclear scintigraphy, US, CT, & MR
            • Associated vesicoureteral reflux (VUR) in ~ 1/3 of cases
            • Permanent scarring is more likely in children < 2 years old
            • Variable presentation: Fever, lethargy, irritability, vomiting, abdominal/flank pain, hematuria, or dysuria
          • Imaging work-up of urinary tract infection (UTI) is controversial; professional society guidelines vary internationally

        IMAGING

        • General Features

          • Radiographic Findings

            • Ultrasonographic Findings

              • CT Findings

                • MR Findings

                  • Nuclear Medicine Findings

                    • Imaging Recommendations

                      DIFFERENTIAL DIAGNOSIS

                        PATHOLOGY

                        • General Features

                          • Gross Pathologic & Surgical Features

                            • Microscopic Features

                              CLINICAL ISSUES

                              • Presentation

                                • Demographics

                                  • Natural History & Prognosis

                                    • Treatment

                                      DIAGNOSTIC CHECKLIST

                                      • Consider

                                        • Image Interpretation Pearls

                                          Selected References

                                          1. 't Hoen LA et al: Update of the EAU/ESPU guidelines on urinary tract infections in children. J Pediatr Urol. 17(2):200-7, 2021
                                          2. Buettcher M et al: Swiss consensus recommendations on urinary tract infections in children. Eur J Pediatr. 180(3):663-74, 2020
                                          3. Freesmeyer M et al: Real-time DMSA-SPECT/US fusion imaging revealing nonscarring loss of function after pyelonephritis. Clin Nucl Med. 45(6):e274-5, 2020
                                          4. Lee YJ et al: Relationship between breastfeeding, birth history, and acute pyelonephritis in infants. J Korean Med Sci. 35(8):e32, 2020
                                          5. Pleniceanu O et al: Acute pyelonephritis in children and the risk of end-stage kidney disease. J Nephrol. ePub, 2020
                                          6. Simrén Y et al: Diffusion weighted imaging is a promising method to detect acute pyelonephritis in non-sedated free breathing infants. J Pediatr Urol. 16(3):320-5, 2020
                                          7. Sjöström S et al: Bladder/bowel dysfunction in pre-school children following febrile urinary tract infection in infancy. Pediatr Nephrol.36(6):1489-97, 2020
                                          8. Warner J et al: Unenhanced MRI of the abdomen and pelvis in the comprehensive evaluation of acute atraumatic abdominal pain in children. AJR Am J Roentgenol. 215(5):1218-28, 2020
                                          9. Zhu H et al: Semiquantitative analysis of power doppler ultrasonography versus Tc-99m DMSA scintigraphy in diagnostic and severity assessment of acute childhood pyelonephritis. Transl Pediatr. 9(4):487-95, 2020
                                          10. Bahat H et al: Predictors of grade 3-5 vesicoureteral reflux in infants ≤2 months of age with pyelonephritis. Pediatr Nephrol. 34(5):907-15, 2019
                                          11. Kosmeri C et al: An update on renal scarring after urinary tract infection in children: what are the risk factors? J Pediatr Urol. 15(6):598-603, 2019
                                          12. Millner R et al: Urinary tract infections. Pediatr Clin North Am. 66(1):1-13, 2019
                                          13. Shaikh N et al: Host and bacterial markers that differ in children with cystitis and pyelonephritis. J Pediatr. 209:146-53.e1, 2019
                                          14. Bosakova A et al: Diffusion-weighted magnetic resonance imaging is more sensitive than dimercaptosuccinic acid scintigraphy in detecting parenchymal lesions in children with acute pyelonephritis: a prospective study. J Pediatr Urol. 14(3):269.e1-7, 2018
                                          15. Lee JW et al: D-dimer as a marker of acute pyelonephritis in infants younger than 24 months with urinary tract infection. Pediatr Nephrol. 33(4):631-7, 2018
                                          16. Palmer LS et al: Cost-effectiveness of antimicrobial prophylaxis for children in the RIVUR trial. World J Urol. 36(9):1441-7, 2018
                                          17. Chung EM et al: Imaging of the pediatric urinary system. Radiol Clin North Am. 55(2):337-57, 2017
                                          18. Expert Panel on Pediatric Imaging:. et al: ACR Appropriateness Criteria® Urinary Tract Infection-Child. J Am Coll Radiol. 14(5S):S362-71, 2017
                                          19. Mattoo TK et al: Interobserver variability for interpretation of DMSA scans in the RIVUR trial. J Pediatr Urol. 13(6):616.e1-6, 2017
                                          20. Arlen AM et al: Computer model predicting breakthrough febrile urinary tract infection in children with primary vesicoureteral reflux. J Pediatr Urol. 12(5):288.e1-5, 2016
                                          21. Reaffirmation of AAP Clinical Practice Guideline: The Diagnosis & Management of the Initial Urinary Tract Infection in Febrile Infants & Young Children 2–24 Months of Age. American Academy of Pediatrics. Published December, 2016. Accessed March 2021. https://pediatrics.aappublications.org/content/138/6/e20163026
                                          22. Zhang GQ et al: The effect of vitamin A on renal damage following acute pyelonephritis in children: a meta-analysis of randomized controlled trials. Pediatr Nephrol. 31(3):373-9, 2016
                                          23. de Bessa J Jr et al: Antibiotic prophylaxis for prevention of febrile urinary tract infections in children with vesicoureteral reflux: a meta-analysis of randomized, controlled trials comparing dilated to nondilated vesicoureteral reflux. J Urol. 193(5 Suppl):1772-7, 2015
                                          24. Morello W et al: Acute pyelonephritis in children. Pediatr Nephrol. 31(8):1253-65, 2015
                                          25. Narchi H et al: Renal tract abnormalities missed in a historical cohort of young children with UTI if the NICE and AAP imaging guidelines were applied. J Pediatr Urol. 11(5):252.e1-7, 2015
                                          26. Shaikh N et al: Procalcitonin, C-reactive protein, and erythrocyte sedimentation rate for the diagnosis of acute pyelonephritis in children. Cochrane Database Syst Rev. 1:CD009185, 2015
                                          27. Sood A et al: Incidence, admission rates, and economic burden of pediatric emergency department visits for urinary tract infection: data from the nationwide emergency department sample, 2006 to 2011. J Pediatr Urol. 11(5):246.e1-8, 2015
                                          28. Cerwinka WH et al: Comparison of magnetic resonance urography to dimercaptosuccinic acid scan for the identification of renal parenchyma defects in children with vesicoureteral reflux. J Pediatr Urol. 10(2):344-51, 2014
                                          29. Jacobson D et al: Perinephric abscesses in the pediatric population: case presentation and review of the literature. Pediatr Nephrol. 29(5):919-25, 2014
                                          30. Strohmeier Y et al: Antibiotics for acute pyelonephritis in children. Cochrane Database Syst Rev. 7:CD003772, 2014
                                          31. Yang TH et al: Obesity and a febrile urinary tract infection: dual burden for young children? Urology. 84(2):445-9, 2014
                                          32. La Scola C et al: Different guidelines for imaging after first UTI in febrile infants: yield, cost, and radiation. Pediatrics. 131(3):e665-71, 2013
                                          33. Leroy S et al: Association of procalcitonin with acute pyelonephritis and renal scars in pediatric UTI. Pediatrics. 131(5):870-9, 2013
                                          34. Shaikh N et al: Risk of renal scarring in children with a first urinary tract infection: a systematic review. Pediatrics. 126(6):1084-91, 2010
                                          35. Brenner M et al: Comparison of 99mTc-DMSA dual-head SPECT versus high-resolution parallel-hole planar imaging for the detection of renal cortical defects. AJR Am J Roentgenol. 193(2):333-7, 2009
                                          36. Siomou E et al: Implications of 99mTc-DMSA scintigraphy performed during urinary tract infection in neonates. Pediatrics. 124(3):881-7, 2009
                                          37. Cerwinka WH et al: Magnetic resonance urography in pediatric urology. J Pediatr Urol. 4(1):74-82; quiz 82-3, 2008
                                          38. Urinary tract infection in children: diagnosis, treatment & long-term management. National Collaborating Centre for Women's & Children's Health. Commissioned by the National Institute for Health & Clinical Excellence. Published August 2007. Updated 2017. Accessed March 2021. https://www.nice.org.uk/guidance/cg54/evidence/full-guideline-pdf-196566877
                                          39. Gonzalez E et al: Impact of vesicoureteral reflux on the size of renal lesions after an episode of acute pyelonephritis. J Urol. 173(2):571-4; discussion 574-5, 2005
                                          40. Wang YT et al: Correlation of renal ultrasonographic findings with inflammatory volume from dimercaptosuccinic acid renal scans in children with acute pyelonephritis. J Urol. 173(1):190-4; discussion 194, 2005
                                          41. Hoberman A et al: Imaging studies after a first febrile urinary tract infection in young children. N Engl J Med. 348(3):195-202, 2003
                                          42. Maturen KE et al: Computed tomographic diagnosis of unsuspected pyelonephritis in children. Can Assoc Radiol J. 53(5):279-83, 2002
                                          43. Kraus SJ: Genitourinary imaging in children. Pediatr Clin North Am. 48(6):1381-424, 2001
                                          44. Majd M et al: Acute pyelonephritis: comparison of diagnosis with 99mTc-DMSA, SPECT, spiral CT, MR imaging, and power Doppler US in an experimental pig model. Radiology. 218(1):101-8, 2001
                                          45. Roberts KB: A synopsis of the American Academy of Pediatrics' practice parameter on the diagnosis, treatment, and evaluation of the initial urinary tract infection in febrile infants and young children. Pediatr Rev. 20(10):344-7, 1999
                                          46. Yen TC et al: Identification of new renal scarring in repeated episodes of acute pyelonephritis using Tc-99m DMSA renal SPECT. Clin Nucl Med. 23(12):828-31, 1998
                                          47. Winters WD: Power Doppler sonographic evaluation of acute pyelonephritis in children. J Ultrasound Med. 15(2):91-6; quiz 97-8, 1996
                                          48. AAP Gateway: Urinary tract infection: clinical practice guideline for the diagnosis & management of the initial UTI in febrile infants & children 2 to 24 months. Published August, 2011. Accessed May 2016. http://pediatrics.aappublications.org/content/early/2011/08/24/peds.2011-1330
                                          49. NICE: NICE guidelines. Published August 2007. Accessed May 2016. https://www.nice.org.uk/guidance/cg54
                                          Related Anatomy
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                                          Related Differential Diagnoses
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                                          References
                                          Tables

                                          Tables

                                          KEY FACTS

                                          • Terminology

                                            • Imaging

                                              • Clinical Issues

                                                TERMINOLOGY

                                                • Synonyms

                                                  • Acute lobar nephronia, focal bacterial nephritis
                                                • Definitions

                                                  • Acute infection of renal parenchyma
                                                  • Overview
                                                    • Classic imaging appearance: Focal swelling & ↓ perfusion of affected parenchyma visible on nuclear scintigraphy, US, CT, & MR
                                                    • Associated vesicoureteral reflux (VUR) in ~ 1/3 of cases
                                                    • Permanent scarring is more likely in children < 2 years old
                                                    • Variable presentation: Fever, lethargy, irritability, vomiting, abdominal/flank pain, hematuria, or dysuria
                                                  • Imaging work-up of urinary tract infection (UTI) is controversial; professional society guidelines vary internationally

                                                IMAGING

                                                • General Features

                                                  • Radiographic Findings

                                                    • Ultrasonographic Findings

                                                      • CT Findings

                                                        • MR Findings

                                                          • Nuclear Medicine Findings

                                                            • Imaging Recommendations

                                                              DIFFERENTIAL DIAGNOSIS

                                                                PATHOLOGY

                                                                • General Features

                                                                  • Gross Pathologic & Surgical Features

                                                                    • Microscopic Features

                                                                      CLINICAL ISSUES

                                                                      • Presentation

                                                                        • Demographics

                                                                          • Natural History & Prognosis

                                                                            • Treatment

                                                                              DIAGNOSTIC CHECKLIST

                                                                              • Consider

                                                                                • Image Interpretation Pearls

                                                                                  Selected References

                                                                                  1. 't Hoen LA et al: Update of the EAU/ESPU guidelines on urinary tract infections in children. J Pediatr Urol. 17(2):200-7, 2021
                                                                                  2. Buettcher M et al: Swiss consensus recommendations on urinary tract infections in children. Eur J Pediatr. 180(3):663-74, 2020
                                                                                  3. Freesmeyer M et al: Real-time DMSA-SPECT/US fusion imaging revealing nonscarring loss of function after pyelonephritis. Clin Nucl Med. 45(6):e274-5, 2020
                                                                                  4. Lee YJ et al: Relationship between breastfeeding, birth history, and acute pyelonephritis in infants. J Korean Med Sci. 35(8):e32, 2020
                                                                                  5. Pleniceanu O et al: Acute pyelonephritis in children and the risk of end-stage kidney disease. J Nephrol. ePub, 2020
                                                                                  6. Simrén Y et al: Diffusion weighted imaging is a promising method to detect acute pyelonephritis in non-sedated free breathing infants. J Pediatr Urol. 16(3):320-5, 2020
                                                                                  7. Sjöström S et al: Bladder/bowel dysfunction in pre-school children following febrile urinary tract infection in infancy. Pediatr Nephrol.36(6):1489-97, 2020
                                                                                  8. Warner J et al: Unenhanced MRI of the abdomen and pelvis in the comprehensive evaluation of acute atraumatic abdominal pain in children. AJR Am J Roentgenol. 215(5):1218-28, 2020
                                                                                  9. Zhu H et al: Semiquantitative analysis of power doppler ultrasonography versus Tc-99m DMSA scintigraphy in diagnostic and severity assessment of acute childhood pyelonephritis. Transl Pediatr. 9(4):487-95, 2020
                                                                                  10. Bahat H et al: Predictors of grade 3-5 vesicoureteral reflux in infants ≤2 months of age with pyelonephritis. Pediatr Nephrol. 34(5):907-15, 2019
                                                                                  11. Kosmeri C et al: An update on renal scarring after urinary tract infection in children: what are the risk factors? J Pediatr Urol. 15(6):598-603, 2019
                                                                                  12. Millner R et al: Urinary tract infections. Pediatr Clin North Am. 66(1):1-13, 2019
                                                                                  13. Shaikh N et al: Host and bacterial markers that differ in children with cystitis and pyelonephritis. J Pediatr. 209:146-53.e1, 2019
                                                                                  14. Bosakova A et al: Diffusion-weighted magnetic resonance imaging is more sensitive than dimercaptosuccinic acid scintigraphy in detecting parenchymal lesions in children with acute pyelonephritis: a prospective study. J Pediatr Urol. 14(3):269.e1-7, 2018
                                                                                  15. Lee JW et al: D-dimer as a marker of acute pyelonephritis in infants younger than 24 months with urinary tract infection. Pediatr Nephrol. 33(4):631-7, 2018
                                                                                  16. Palmer LS et al: Cost-effectiveness of antimicrobial prophylaxis for children in the RIVUR trial. World J Urol. 36(9):1441-7, 2018
                                                                                  17. Chung EM et al: Imaging of the pediatric urinary system. Radiol Clin North Am. 55(2):337-57, 2017
                                                                                  18. Expert Panel on Pediatric Imaging:. et al: ACR Appropriateness Criteria® Urinary Tract Infection-Child. J Am Coll Radiol. 14(5S):S362-71, 2017
                                                                                  19. Mattoo TK et al: Interobserver variability for interpretation of DMSA scans in the RIVUR trial. J Pediatr Urol. 13(6):616.e1-6, 2017
                                                                                  20. Arlen AM et al: Computer model predicting breakthrough febrile urinary tract infection in children with primary vesicoureteral reflux. J Pediatr Urol. 12(5):288.e1-5, 2016
                                                                                  21. Reaffirmation of AAP Clinical Practice Guideline: The Diagnosis & Management of the Initial Urinary Tract Infection in Febrile Infants & Young Children 2–24 Months of Age. American Academy of Pediatrics. Published December, 2016. Accessed March 2021. https://pediatrics.aappublications.org/content/138/6/e20163026
                                                                                  22. Zhang GQ et al: The effect of vitamin A on renal damage following acute pyelonephritis in children: a meta-analysis of randomized controlled trials. Pediatr Nephrol. 31(3):373-9, 2016
                                                                                  23. de Bessa J Jr et al: Antibiotic prophylaxis for prevention of febrile urinary tract infections in children with vesicoureteral reflux: a meta-analysis of randomized, controlled trials comparing dilated to nondilated vesicoureteral reflux. J Urol. 193(5 Suppl):1772-7, 2015
                                                                                  24. Morello W et al: Acute pyelonephritis in children. Pediatr Nephrol. 31(8):1253-65, 2015
                                                                                  25. Narchi H et al: Renal tract abnormalities missed in a historical cohort of young children with UTI if the NICE and AAP imaging guidelines were applied. J Pediatr Urol. 11(5):252.e1-7, 2015
                                                                                  26. Shaikh N et al: Procalcitonin, C-reactive protein, and erythrocyte sedimentation rate for the diagnosis of acute pyelonephritis in children. Cochrane Database Syst Rev. 1:CD009185, 2015
                                                                                  27. Sood A et al: Incidence, admission rates, and economic burden of pediatric emergency department visits for urinary tract infection: data from the nationwide emergency department sample, 2006 to 2011. J Pediatr Urol. 11(5):246.e1-8, 2015
                                                                                  28. Cerwinka WH et al: Comparison of magnetic resonance urography to dimercaptosuccinic acid scan for the identification of renal parenchyma defects in children with vesicoureteral reflux. J Pediatr Urol. 10(2):344-51, 2014
                                                                                  29. Jacobson D et al: Perinephric abscesses in the pediatric population: case presentation and review of the literature. Pediatr Nephrol. 29(5):919-25, 2014
                                                                                  30. Strohmeier Y et al: Antibiotics for acute pyelonephritis in children. Cochrane Database Syst Rev. 7:CD003772, 2014
                                                                                  31. Yang TH et al: Obesity and a febrile urinary tract infection: dual burden for young children? Urology. 84(2):445-9, 2014
                                                                                  32. La Scola C et al: Different guidelines for imaging after first UTI in febrile infants: yield, cost, and radiation. Pediatrics. 131(3):e665-71, 2013
                                                                                  33. Leroy S et al: Association of procalcitonin with acute pyelonephritis and renal scars in pediatric UTI. Pediatrics. 131(5):870-9, 2013
                                                                                  34. Shaikh N et al: Risk of renal scarring in children with a first urinary tract infection: a systematic review. Pediatrics. 126(6):1084-91, 2010
                                                                                  35. Brenner M et al: Comparison of 99mTc-DMSA dual-head SPECT versus high-resolution parallel-hole planar imaging for the detection of renal cortical defects. AJR Am J Roentgenol. 193(2):333-7, 2009
                                                                                  36. Siomou E et al: Implications of 99mTc-DMSA scintigraphy performed during urinary tract infection in neonates. Pediatrics. 124(3):881-7, 2009
                                                                                  37. Cerwinka WH et al: Magnetic resonance urography in pediatric urology. J Pediatr Urol. 4(1):74-82; quiz 82-3, 2008
                                                                                  38. Urinary tract infection in children: diagnosis, treatment & long-term management. National Collaborating Centre for Women's & Children's Health. Commissioned by the National Institute for Health & Clinical Excellence. Published August 2007. Updated 2017. Accessed March 2021. https://www.nice.org.uk/guidance/cg54/evidence/full-guideline-pdf-196566877
                                                                                  39. Gonzalez E et al: Impact of vesicoureteral reflux on the size of renal lesions after an episode of acute pyelonephritis. J Urol. 173(2):571-4; discussion 574-5, 2005
                                                                                  40. Wang YT et al: Correlation of renal ultrasonographic findings with inflammatory volume from dimercaptosuccinic acid renal scans in children with acute pyelonephritis. J Urol. 173(1):190-4; discussion 194, 2005
                                                                                  41. Hoberman A et al: Imaging studies after a first febrile urinary tract infection in young children. N Engl J Med. 348(3):195-202, 2003
                                                                                  42. Maturen KE et al: Computed tomographic diagnosis of unsuspected pyelonephritis in children. Can Assoc Radiol J. 53(5):279-83, 2002
                                                                                  43. Kraus SJ: Genitourinary imaging in children. Pediatr Clin North Am. 48(6):1381-424, 2001
                                                                                  44. Majd M et al: Acute pyelonephritis: comparison of diagnosis with 99mTc-DMSA, SPECT, spiral CT, MR imaging, and power Doppler US in an experimental pig model. Radiology. 218(1):101-8, 2001
                                                                                  45. Roberts KB: A synopsis of the American Academy of Pediatrics' practice parameter on the diagnosis, treatment, and evaluation of the initial urinary tract infection in febrile infants and young children. Pediatr Rev. 20(10):344-7, 1999
                                                                                  46. Yen TC et al: Identification of new renal scarring in repeated episodes of acute pyelonephritis using Tc-99m DMSA renal SPECT. Clin Nucl Med. 23(12):828-31, 1998
                                                                                  47. Winters WD: Power Doppler sonographic evaluation of acute pyelonephritis in children. J Ultrasound Med. 15(2):91-6; quiz 97-8, 1996
                                                                                  48. AAP Gateway: Urinary tract infection: clinical practice guideline for the diagnosis & management of the initial UTI in febrile infants & children 2 to 24 months. Published August, 2011. Accessed May 2016. http://pediatrics.aappublications.org/content/early/2011/08/24/peds.2011-1330
                                                                                  49. NICE: NICE guidelines. Published August 2007. Accessed May 2016. https://www.nice.org.uk/guidance/cg54