eMedicine Specialties > Radiology > Genitourinary

Emphysematous Pyelonephritis: Imaging

Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR, LRCP, Chairman of Medical Imaging, Professor of Radiology, NGHA, King Fahad National Guard Hospital, King Abdulaziz Medical City, Riyadh, Saudi Arabia
Coauthor(s): Sumaira MacDonald, MBChB, PhD, MRCP, FRCR, Lecturer, Sheffield University Medical School; Endovascular Fellow, Sheffield Vascular Institute; Colm Boylan, MRCP, FRCR, Specialist Registrar, Department of Radiology, North Manchester General Hospital NHS Trust, UK; Brendan Costello, MD, Clinical Director, Department of Urology, North Manchester General Hospital; Khalid Mahmood, MBBS, FCPS, Locum Appointment Training Specialist Registrar, Department of Radiology - Paediatric, Royal Liverpool (Alder Hey) Children's Hospital
Contributor Information and Disclosures

Updated: Jan 25, 2008

Radiography

Findings

  • Plain radiographs may show bubbles of gas within the region of the renal bed and in the upper renal collecting system. These may be diagnostic in the appropriate clinical setting.14
  • Gas within the collecting system without evidence of renal parenchymal gas may be seen in patients with diabetes and does not have the same ominous prognosis.
  • Intravenous urography shows significant renal enlargement associated with delayed or absent excretion.
  • Acute renal edema with obliteration of the renal pelvis can be seen.
  • Retrograde pyelography can be used to establish the presence of ureteral obstruction.

Degree of Confidence

Plain radiographic findings may be diagnostic in ill patients with diabetes who have signs of acute pyelonephritis.

False Positives/Negatives

Renal fossa gas may be confused with gastrointestinal gas. A false-positive diagnosis may occur with retroperitoneal gas and a psoas abscess secondary to gas-forming organisms. Reflux of air from the bladder and bronchorenal, enterorenal, or cutaneorenal fistulae (as may occur with xanthogranulomatous pyelonephritis17 ) may also lead to false-positive findings. Air can be seen in focal renal abscesses.

Computed Tomography

Findings

CT is the examination of choice for diagnosing EPN.13,16,19

  • Intraparenchymal, intracalyceal, and intrapelvic gas and extension into the perinephric space are readily identified on nonenhanced CT scans.19
  • Mottled areas of low attenuation extend radially along the pyramids.
  • Occasionally, pus may be seen extending into the renal veins.

Degree of Confidence

CT is the most reliable and sensitive modality in diagnosing EPN.

False Positives/Negatives

EPN should be differentiated from reflux of air from the bladder and bronchorenal, enterorenal, or cutaneorenal fistulae (as may occur with xanthogranulomatous pyelonephritis17 ). Air also can be seen in focal renal abscesses, but it is not life threatening.

Magnetic Resonance Imaging

Findings

MRI is not the modality of choice in the diagnosis of EPN. MRI findings reported are a signal void on both T1-weighted and T2-weighted images. Perinephric and intraparenchymal fluid collections are demonstrated well on MRIs.13,14

Degree of Confidence

MRI is not the modality of choice in the diagnosis of EPN. When CT is available, it should be used instead.

False Positives/Negatives

Signal voids on MRIs may occur with renal calculi or rapidly flowing blood.

Ultrasonography

Findings

  • Intrarenal gas causes high-amplitude echoes within the renal sinus/renal parenchyma associated with dirty acoustic shadowing.
  • Ring-down artifacts may result from air bubbles trapped in fluid.
  • Shadowing from gas bubbles in the perinephric space may be seen. These make visualization of the kidney difficult.
  • Perinephric fluid, if any, tends to be obscured by gas.

Degree of Confidence

Ultrasonography is usually the first imaging modality for assessing renal pathology. The sonographic findings often guide clinicians in choosing the next modality, such as CT, to achieve a more specific diagnosis.13

False Positives/Negatives

Gas within the kidney and/or renal pelvis mimics renal calculi. In select patients, particularly those with diabetes in whom sonograms suggest renal calculi, obtaining a coned radiograph of the renal area is worthwhile to preclude missing an EPN.

Nuclear Imaging

Findings

Radionuclide studies are nonspecific; therefore, they have a limited role in the evaluation of EPN. However, radionuclide study is an excellent modality for assessing differential function when nephrectomy is contemplated. Scintigraphy has been used to evaluate responses to antimicrobial therapy.

More on Emphysematous Pyelonephritis

Overview: Emphysematous Pyelonephritis
Imaging: Emphysematous Pyelonephritis
Follow-up: Emphysematous Pyelonephritis
Multimedia: Emphysematous Pyelonephritis
References
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References

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  2. Jain SK, Agarwal N, Chaturvedi SK. Emphysematous pyelonephritis: a rare presentation. J Postgrad Med. Jan-Mar 2000;46(1):31-2. [Medline].

  3. Roy C, Pfleger DD, Tuchmann CM, et al. Emphysematous pyelitis: findings in five patients. Radiology. Mar 2001;218(3):647-50. [Medline].

  4. Sathyanathan VP, Gomathy S, Potty RN, et al. Emphysematous pyelonephritis. J Assoc Physicians India. Jun 1998;46(6):562-3. [Medline].

  5. Shokeir AA, El-Azab M, Mohsen T, El-Diasty T. Emphysematous pyelonephritis: a 15-year experience with 20 cases. Urology. Mar 1997;49(3):343-6. [Medline].

  6. Falagas ME, Alexiou VG, Giannopoulou KP, Siempos II. Risk factors for mortality in patients with emphysematous pyelonephritis: a meta-analysis. J Urol. Sep 2007;178(3 Pt 1):880-5; quiz 1129. [Medline].

  7. Ronald A, Ludwig E. Urinary tract infections in adults with diabetes. Int J Antimicrob Agents. Apr 2001;17(4):287-92. [Medline].

  8. Tang HJ, Li CM, Yen MY, et al. Clinical characteristics of emphysematous pyelonephritis. J Microbiol Immunol Infect. Jun 2001;34(2):125-30. [Medline].

  9. Dahnart W. Radiology Review Manual. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2007.

  10. Komura S, Shindoh N, Minowa O, et al. Emphysematous pyelonephritis- conversion of type i to type II appearance on serial CT studies. Clin Imaging. Nov-Dec 1999;23(6):386-8. [Medline].

  11. Wan YL, Lee TY, Bullard MJ, Tsai CC. Acute gas-producing bacterial renal infection: correlation between imaging findings and clinical outcome. Radiology. Feb 1996;198(2):433-8. [Medline].

  12. Best CD, Terris MK, Tacker JR, Reese JH. Clinical and radiological findings in patients with gas forming renal abscess treated conservatively. J Urol. Oct 1999;162(4):1273-6. [Medline].

  13. Grozel F, Berthezene Y, Guerin C, et al. Bilateral emphysematous pyelonephritis resolving to medical therapy: demonstration by US and CT. Eur Radiol. 1997;7(6):844-6. [Medline].

  14. Huang JJ, Tseng CC. Emphysematous pyelonephritis: clinicoradiological classification, management, prognosis, and pathogenesis. Arch Intern Med. Mar 27 2000;160(6):797-805. [Medline].

  15. Kuo YT, Chen MT, Liu GC, et al. Emphysematous pyelonephritis: imaging diagnosis and follow-up. Kaohsiung J Med Sci. Mar 1999;15(3):159-70. [Medline].

  16. Craig WD, Wagner BJ, Travis MD. Pyelonephritis: radiologic-pathologic review. Radiographics. Jan-Feb 2008;28(1):255-77; quiz 327-8. [Medline].

  17. Punekar SV, Kinne JS, Rao SR, et al. Xanthogranulomatous pyelonephritis presenting as emphysematous pyelonephritis: a rare association. J Postgrad Med. Oct-Dec 1999;45(4):125. [Medline].

  18. Singh I, Pachisia SS, Kumar S, Arora VK, Kumar P. Emphysematous pyelonephritis: a consequence of adenocarcinoma of urinary bladder in a nondiabetic patient. J Postgrad Med. Oct-Dec 2005;51(4):324-5. [Medline].

  19. Portnoy O, Apter S, Koukoui O, Konen E, Amitai MM, Sella T. Gas in the kidney: CT findings. Emerg Radiol. Jun 2007;14(2):83-7. [Medline].

  20. Chen MT, Huang CN, Chou YH, et al. Percutaneous drainage in the treatment of emphysematous pyelonephritis: 10-year experience. J Urol. May 1997;157(5):1569-73. [Medline].

  21. Roberts JA. Management of pyelonephritis and upper urinary tract infections. Urol Clin North Am. Nov 1999;26(4):753-63. [Medline].

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Further Reading

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Keywords

EPN, upper urinary tract infection, renal tract infections with intraparenchymal renal gas, emphysematous pyelitis, perinephric emphysema, urinary tract infection, gas in the kidney, renal gas, Escherichia coli, E coli, Klebsiella pneumoniae, K pneumoniae, Proteus mirabilis, P mirabilis

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Contributor Information and Disclosures

Author

Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR, LRCP, Chairman of Medical Imaging, Professor of Radiology, NGHA, King Fahad National Guard Hospital, King Abdulaziz Medical City, Riyadh, Saudi Arabia
Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR, LRCP is a member of the following medical societies: American Institute of Ultrasound in Medicine, Radiological Society of North America, Royal College of Physicians, Royal College of Physicians and Surgeons of the United States, Royal College of Radiologists, and Royal College of Surgeons of England
Disclosure: Nothing to disclose.

Coauthor(s)

Sumaira MacDonald, MBChB, PhD, MRCP, FRCR, Lecturer, Sheffield University Medical School; Endovascular Fellow, Sheffield Vascular Institute
Sumaira MacDonald, MBChB, PhD, MRCP, FRCR is a member of the following medical societies: British Medical Association, Royal College of Physicians, and Royal College of Radiologists
Disclosure: Nothing to disclose.

Colm Boylan, MRCP, FRCR, Specialist Registrar, Department of Radiology, North Manchester General Hospital NHS Trust, UK
Colm Boylan, MRCP, FRCR is a member of the following medical societies: Royal College of Radiologists
Disclosure: Nothing to disclose.

Brendan Costello, MD, Clinical Director, Department of Urology, North Manchester General Hospital
Brendan Costello, MD is a member of the following medical societies: British Medical Association
Disclosure: Nothing to disclose.

Khalid Mahmood, MBBS, FCPS, Locum Appointment Training Specialist Registrar, Department of Radiology - Paediatric, Royal Liverpool (Alder Hey) Children's Hospital
Disclosure: Nothing to disclose.

Medical Editor

Steven Perlmutter, MD, FACR, Clinical Associate Professor, Radiology Residency Program Director, Radiology Medical Director, Department of Radiology, University Hospital at Stony Brook
Steven Perlmutter, MD, FACR is a member of the following medical societies: American College of Radiology, American Institute of Ultrasound in Medicine, American Medical Association, American Roentgen Ray Society, Association of Program Directors in Radiology, Association of University Radiologists, Medical Society of the State of New York, Radiological Society of North America, Society of Breast Imaging, Society of Nuclear Medicine, and Society of Uroradiology
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

Arnold C Friedman, MD, FACR, Associate Chairman, Department of Radiology, University of Florida Health Science Center; Chief, Department of Radiology, Shands-Jacksonville Hospital
Arnold C Friedman, MD, FACR is a member of the following medical societies: American College of Radiology, American Institute of Ultrasound in Medicine, American Roentgen Ray Society, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

Eugene C Lin, MD, Consulting Staff, Department of Radiology, Virginia Mason Medical Center
Eugene C Lin, MD is a member of the following medical societies: American College of Nuclear Medicine, American College of Radiology, Radiological Society of North America, and Society of Nuclear Medicine
Disclosure: Nothing to disclose.

 
 
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