Severe emphysematous pyelonephritis managed with staged percutaneous drainage – A Changing paradigm

Abstract

Emphysematous pyelonephritis (EPN) is a potentially life-threatening infection of the renal parenchyma and perinephric tissues by gas-forming organisms. Historically, open surgical drainage or nephrectomy was the standard of care, however, in recent years percutaneous drainage as a minimally invasive approach has become popular. However, whether percutaneous drainage can be successful in more severe cases of EPN is less clear. We report a case of severe Class IIIb EPN managed successfully with multiple staged percutaneous drainage procedures guided by interval re-assessment of clinical, biochemical, and radiological progress in a 52-year-old male with poorly controlled Type 2 Diabetes.

1 Introduction

Emphysematous pyelonephritis (EPN) is a life-threatening, necrotising infection of the renal parenchyma and perinephric tissues by gas-forming organisms. The concept of emphysematous urinary tract infections was introduced in 1898 by Kelly and MacCallum who proposed that fermentation by certain organisms would cause pneumaturia. The term emphysematous pyelonephritis was subsequently coined in 1962 to describe this process.

Classically, EPN occurs in diabetic or immunocompromised patients, or in the setting of obstructive uropathy, and is more common in female patients. The commonest pathogens isolated from patients with EPN include Escherichia coli followed by Klebsiella pneumoniae, with other culprit organisms including Proteus and Pseudomonas species, or rarely fungal organisms such as Candida species. Gas production occurs during the fermentation of glucose into hydrogen and carbon dioxide gas and this process is facilitated in diabetic patients by glycosuria, blunted immune responses, and microangiopathy which promote the propagation of infection. Urinary obstruction produces parenchymal ischaemia and necrosis, favouring infection. In non-diabetic patients with EPN, obstructive uropathy is almost always present.

Imaging is essential to the diagnosis of EPN, with computed tomography (CT) being the gold standard, demonstrating the presence of gas within the renal parenchyma, collecting system, or perinephric tissues. Two subtypes of EPN were identified by Wan et al., in 1996 based on patterns of gas distribution and parenchymal destruction. Type I EPN was characterised by extensive parenchymal destruction with minimal perinephric fluid collections and a streaky or mottled gas pattern, whilst Type II EPN was defined by fluid collections with locules or bubbles of gas. In 2000, Huang and Tseng developed a radiological classification of EPN based on the extent of gas ( Table 1 ). These classifications were of prognostic significance, with Type I EPN, and a greater degree of gas extension generally predictive of poorer outcome. ^, Additionally, imaging is essential in identifying whether upper tract obstruction is present so that urgent decompression can be pursued.

Table 1

– Huang and Tseng classification of emphysematous pyelonephritis.

Huang and Tseng Class of Emphysematous Pyelonephritis	Extent of gas
Class I	Gas in the collecting system
Class II	Gas limited to the renal parenchyma
Class IIIb	Gas extending into the perinephric space
Class IIIb	Gas extending into the pararenal space (gas extension beyond Gerota’s fascia)
Class IV	Bilateral emphysematous pyelonephritis or EPN in a solitary kidney

Historical approaches to managing EPN involved either medical management alone with intravenous antibiotics in milder cases, or in conjunction with nephrectomy or open surgical drainage for source control. EPN was a fatal disease, with a reported mortality of up to 50 % depending upon patient and disease factors, with poorer outcomes in non-surgically managed cases. Recently, there has been a paradigm shift towards percutaneous drainage as a minimally-invasive, nephron-sparing alternative to surgery in managing EPN with positive outcomes reported in a number of case reports and case series’. Subsequent attempts at risk stratification to identify clinical, biochemical, or imaging characteristics that would identify patients suitable for minimally-invasive approaches and those who would require early nephrectomy have been inconclusive. Whether percutaneous drainage is a feasible technique in patients who have extensive unilateral EPN, or other high-risk features is not established, and a patient-specific approach is needed.

We present a case of severe class IIIb emphysematous pyelonephritis in a 52-year-old male successfully managed with multiple staged percutaneous drain insertions over a period of 32 days. To our knowledge, this is the first reported case of EPN managed using multiple planned percutaneous drainage procedures based on frequent assessment of radiological, clinical, and biochemical progress until resolution. This supports the growing paradigm that EPN can be initially managed using percutaneous drainage, with nephrectomy reserved for cases where patients have clinical deterioration despite minimally-invasive source control.

2 Case description

A 52-year-old male presented to the Emergency Department of a sub-acute hospital with 2 days of lethargy and high-grade fevers. On presentation, he met sepsis criteria with hypotension, tachycardia, and altered mental status, and received 6 L of intravenous crystalloid to maintain a non-invasive mean arterial pressure (MAP) greater than 60 mmHg. The patient reported no focal infective symptoms, though, initial investigations revealed a random blood sugar level of 29.0mmol/L, and a urinalysis positive for leukocytes and nitrites ( Table 2 ). A CT of the Abdomen and Pelvis with portal venous phase contrast revealed severe left-sided Huang and Tseng class IIIb emphysematous pyelonephritis with retroperitoneal gas extension ( Fig. 1 ).

Table 2

– Summary of relevant biochemical investigations on admission.

Investigation	Result
pH	7.45
pCO2	26 mmHg
HCO3	18mmol/L
Base excess	−4.5mmol/L
Sodium	123mmol/L
Lactate	2.4mmol/L
Urea	10.0mmol/L
Creatinine	124mmol/L
C reactive protein	342mg/L
White cell count	8.7 x 10 ⁹cells/L
Platelets	107 x 10 ⁹cells/L
Neutrophils	7.6 x 10 ⁹cells/L