A Severe Case of Emphysematous Pyelonephritis

This is the case of a 59-year-old woman who presented with first-time diabetic ketoacidosis on a one-week history of severe generalised abdominal pain.  Her inflammatory markers were severely elevated with a C-reactive protein of greater than 700, and her renal function was markedly deranged with a serum creatinine of 220 micromoles/L. She was subsequently admitted to ICU.

An initial CT abdomen/pelvis showed enlarged and destroyed left renal parenchyma with gas fluid levels in the perinephric space and destruction of greater than 75% of the renal parenchyma. There was also significant finding of retroperitoneal free gas. (Images 1a,1b,1c)

After multidisciplinary discussion, a decision was reached that a nephrostomy would be inserted by the Interventional Radiology team. Foul-smelling gas was released from the left flank airspace. A 10.2-Fr Cook MP catheter was inserted and left on free drainage. (Images 2a,2b,2c)

A follow-up CT abdomen/pelvis showed a reduction in size of the air and fluid collection in the left perinephric space, now measuring 10.2 cm compared to 12.3 cm previously, and improved inflammatory change around the left PUJ and proximal ureter. There was also a decrease in the remaining enhancing left renal parenchyma. (Images 3a,3b,3c)

Background

Emphysematous pyelonephritis is an acute severe necrotizing infection of the renal parenchyma and surrounding tissues that results in the presence of gas in the renal parenchyma, collecting system, or perinephric tissue. A background of uncontrolled diabetes mellitus is seen in up to 95% of patients and was seen in this case. [1] Septic complications are the primary cause of mortality, with mortality rates approaching 50%. [2] Due to the rarity of the disease, much of the literature centres upon case reports, and as a result, there is lack of best management guidelines, with many patients often requiring nephrectomy due to failed antimicrobial response. In 2008, Derouiche et al. published a paper on the management of Emphysematous Pyelonephritis based on a series of 21 case reports. Of note from this study, a range of management strategies were utilised, from surgical to conservative, with no best management conclusions able to be drawn. CT was, however, the imaging modality used to establish diagnosis in all 21 cases.

Clinical Perspective

Due to the rarity of the condition, clinical diagnosis is difficult, with patients often presenting with severe sepsis. Pneumaturia may be present but clinical assessment remains a poor diagnostic marker. Imaging is required to reach a diagnosis of emphysematous pyelonephritis, and CT remains the most reliable diagnostic modality. [3]

Imaging Perspective

With clinical assessment being an unreliable diagnostic tool in emphysematous pyelonephritis, early imaging is fundamental. CT is considered diagnostic and is used to assess the presence of gas in the renal parenchyma, collecting system, or perinephric tissue. In our case, there was destruction of greater than 75% of the renal parenchyma.

Outcome

After careful consideration, a decision was reached to perform percutaneous drainage of the left kidney.  A 10.2-Fr Cook multipurpose catheter was inserted into the peri-renal bed by the Interventional-Radiology team. Foul-smelling gas was aspirated, and the catheter was left on free drainage. Follow-up CTs showed decreased peri-renal and retroperitoneal free air post drain insertion, with improved inflammatory change around the left PUJ and proximal ureter, as well as an interval decrease in the remaining enhancing left renal parenchyma. In addition, there was a pronounced improvement in inflammatory markers and eventual normalisation of renal function.

Take-Home Message / Teaching Points

Early clinical suspicion with early imaging and subsequent diagnosis can allow for multidisciplinary conservative management, including Diagnostic and Interventional Radiology, and potentially prevent the need for nephrectomy even in severe instances, as was demonstrated by this interesting case report.

Written informed patient consent for publication has been obtained.