Bilateral emphysematous pyelonephritis

1. Introduction

Emphysematous Pyelonephritis (EPN) is a rare necrotizing infection defined by gas production in the renal system. Bilateral disease has only been reported to occur in 10% of cases.¹ This condition is considered a urologic emergency as mortality and morbidity rates are exceedingly high. The most common predisposing factor to developing EPN, is long-term poorly controlled Diabetes Mellitus (DM), particularly in females.² Early intervention is crucial in decreasing mortality rates, though there is still discussion of the appropriate management. This report presents the unsuccessful conservative management of a critically ill patient with bilateral disease.

2. Case presentation

A 76-year-old diabetic female presented to the Emergency Department with altered mental status after being found down in a pool of blood and urine. Gross hematuria was noted after placement of Foley catheter, though physical exam was inconclusive due to the patient's altered mental status. The patient was afebrile and laboratory results showed multiple abnormalities, including blood urea nitrogen of 110 mg/dL and serum creatinine of 3.4 mg/dL. Complete blood count demonstrated thrombocytopenia and leukocytosis with left shift. Blood culture produced gram-negative rods, and grew Escherichia coli the next day. Relevant results of non-contrast Computed Tomography (CT) were read as status post bilateral nephrectomy with retroperitoneal extraluminal air occupying the empty renal fossae, despite any surgical history of such operation, and air within the lumen of the bladder and bladder wall thickening (Image 1–3). These findings were misinterpreted by the radiologist as anephria due to severe gas collections in both the kidney parenchyma and collecting system bilaterally, distorting the normal renal anatomy. Overall, initial work up resulted in the diagnosis of severe sepsis, hyperosmolar hyperglycemic non-ketotic syndrome, and acute kidney injury.

The patient was transferred to the Medical Intensive Care Unit and following fluid resuscitation, glucose control, administration of antibiotics, and pressor support, the patient was stabilized overnight, but remained anuric in critical condition with multisystem organ dysfunction on multiple inotropic agents. After review of CT imaging by the Urology team, the corrected interpretation yielded a diagnosis of bilateral emphysematous pyelonephritis. Emergent bilateral nephrectomy was strongly considered, but due to the patient's poor functional condition, poor cardiac and pulmonary status, and risk of intra-operative hypotension and death with significant blood loss, a more conservative, non-surgical approach was chosen.

In the operating room, cystoscopy with bilateral retrograde pyelogram was performed for the placement of ureteral stents on hospital day 2. Upon placement of the stents, gross purulent discharge was visualized. The patient tolerated this operation well. On hospital day 3, the patient remained anuric, so interventional radiology was consulted to place bilateral percutaneous renal abscess drains. Ultimately, neither stents nor percutaneous drains yielded significant output or improvement in the patient's clinical condition, and the patient expired on hospital day 5 (see Fig. 1, Fig. 2, Fig. 3).

Fig. 1.

Coronal view of the non-contrast computed tomography showing gas found within the renal parenchyma bilaterally (red arrows).

Fig. 2.

Transverse view of the non-contrast computed tomography showing gas within the renal parenchyma bilaterally (red arrows).

Fig. 3.

Transverse view of the non-contrast computed tomography showing gas within the bladder lumen and bladder wall thickening (red arrow).

3. Discussion

EPN is a rare disease defined by the acute necrosis and presence of gas within the renal parenchyma, collecting system, or perirenal tissue.¹ While the exact pathogenesis is still unclear, the primary factors for development are suggested to be hyperglycemia, decreased tissue perfusion, or impaired immune function, coupled with a gas-producing bacterial infection.¹ Each of these factors can be found in DM, explaining why DM has been reported in up to 90% of EPN.² Escherichia coli has been shown to be the predominant causative organism of EPN followed by Klebsiella, Proteus, and Pseudomonas.^1,2

Numerous clinical pictures have been described for EPN, but most common features are the classic signs of urinary tract infections, thrombocytopenia, renal impairment, altered mental status, and shock.^1,2 However, none of these findings help to differentiate EPN from other diseases, demonstrating the importance of radiologic findings.^1,2 The utility of plain X-ray or ultrasound in EPN is limited as studies have shown they are inferior to CT.³ The Huang classification system, based on CT findings of gas collection, is described as the most useful diagnostic and prognostic factor for EPN.1, 2, 3 Our patient's radiologic findings were initially misinterpreted as anephria by the radiologist, delaying diagnosis and surgical intervention. Emergent management is necessary and especially important of critically ill patients or those with bilateral disease, such as in our patient.

The management of EPN is a multifaceted approach initially focusing on fluid resuscitation, glucose control, and antibiotic treatment.² Traditionally, radical nephrectomy was the primary approach to EPN, due to poor outcomes for conservative management previously reported.¹ Concerns of radical nephrectomies include whether the patients are candidates for such invasive procedures and the potential lifelong implications of renal replacement therapy for nephrectomies, particularly in bilateral cases. Conservative approaches include intensive medical management, placement of ureteral stents and percutaneous drainage. Recently, Wang et al. described the successful use of vacuum sealing drainage while sparing the kidney from nephrectomy.⁴

Overall, the mortality rates of EPN have dropped to 21% due to improvements of imaging, antibiotics, and other management techniques over the years.¹ In recent studies, conservative management has been shown to be as effective as nephrectomy, even in bilateral disease, and associated with lower mortality rates.^1,2 However, the management for different severities of EPN is still unclear as there are conflicting reports as to whether emergent nephrectomy should be indicated in critically ill patients with severe EPN.^1,2,5

4. Conclusion

EPN is an emergent urological disease requiring immediate intervention to resolve. Early diagnosis via CT scan imaging is key to allow for timely management. While conservative management has been shown to be appropriate in many cases, literature is still unclear on the appropriate management of critically ill patients. The present case demonstrates the need for clinical awareness of the radiologic findings of this disease to avoid misinterpretation, and further investigation into the management of severe cases of EPN in patients deemed poor surgical candidates.

Conflicts of interest

None.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Appendix A. Supplementary data

The following is the supplementary data related to this article: