Year : 2009 | Volume
: 20 | Issue : 5 | Page : 838--841
Emphysematous pyelonephritis - case report and evaluation of radiological features
Ritesh Mongha, Bansal Punit, Das K Ranjit, Kundu K Anup
Department of Urology, Institute of Post Graduate Medical Education and Research, Kolkata, India
Department of Urology, IPGMER and SSKM Hospital, Kolkata
Emphysematous pyelonephritis (EPN) is an acute necrotizing parenchymal and perirenal infection caused by gas-forming uropathogens. The predisposing factors are diabetes mellitus and ureteric obstruction. E. coli is the most frequently identified pathogen. The overall mortality is 43%. Computerized tomography (CT) is the imaging procedure of choice in determining the extent of infection and guiding management. Management of EPN has evolved from aggressive surgical intervention to conservative management. Although there are reports of improved renal function after medical therapy combined with relief of obstruction, most of the patients still require nephrectomy. We present a case of EPN and also evaluate the radiological features, prognosis, and current management of this disease.
|How to cite this article:|
Mongha R, Punit B, Ranjit DK, Anup KK. Emphysematous pyelonephritis - case report and evaluation of radiological features.Saudi J Kidney Dis Transpl 2009;20:838-841
|How to cite this URL:|
Mongha R, Punit B, Ranjit DK, Anup KK. Emphysematous pyelonephritis - case report and evaluation of radiological features. Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2021 Nov 30 ];20:838-841
Available from: https://www.sjkdt.org/text.asp?2009/20/5/838/55373
Emphysematous pyelonephritis (EPN) is a rare condition. It is an acute necrotizing parenchymal and perirenal infection caused by gasforming uropathogens. Most busy urological departments get to see around one case yearly. Because of its rarity, most of the information has been from case reports. We present a case of EPN with an evaluation of radiological features, prognostic factors, and current management of this disease.
A 40-year-old man presented to the emergency room with complaints of pain left side upper abdomen and fever with chills for the previous 7 days. There was no significant past medical or surgical history.The patient appeared alert and oriented, but dehydrated. There was a tender lump palpable in his left upper quadrent of the abdomen.
The laboratory invesigations revealed hemoglobin; 11 g/dL, total leukocyte count; 12,800 with polymorphs 90%, random blood glucose: 364 mg/dL, blood urea nitrogen (BUN): 78 mg/ dL, creatinine: 1.6 mg/dL, serum Na + : 126 mmol/ L, and K + : 3.8 mmol/L. The urinalysis showed plenty of pus cells with glucosuria. Urine culture grew E. coli with sensitivity to ceftriaxone and levofloxacin. The KUB X-ray did not reveal reveal any radio-opaque shadows. The utrasound demonstrated a heterogenous mass replacing the whole left kidney with the presence of strong focal echoes suggesting intraparenchymal gas [Figure 1].
The patient was hydrated, and intravenous ceftriaxone 2 g i.v. twice daily was administered. He responded to conservative measures including the initiation of insulin injections. Noncontrast CT scan was done, which showed renal and perirenal fluid collections with gas in the collecting system [Figure 2], intraparenchymal gas [Figure 3] and extension of gas into the perinephric space [Figure 4]. The left sided ureter was also dilated. We contemplated double-J stenting of the left side, but on the 2 nd day of admission, the patient had sudden onset frank pyuria, which drained around one liter of pus with resolution of the lump and fever. He was continued on conservative management with oral Levofloxacin after 7 days of parenteral therapy, and his blood sugar was controlled. His renal function tests improved to BUN 36 mg/dL and creatinine 1 mg/dL. After 4 weeks, his DMSA scan showed no cortical uptake on left side. Eventually, a left side nephrectomy was performed, and the post-operative period was uneventful.
The predisposing factors EPN are diabetes mellitus and ureteric obstruction. All the documented cases of emphysematous pyelonephritis have been in adults.  Juvenile diabetic patients do not appear to be at risk, and women are affected more often than men. Almost all patients display the classic triad of fever, vomiting, and flank pain.  Pneumaturia is absent unless the infection involves the collecting system. Bacteriuria, positive blood culture results, and leukocytosis are often present. Results of urine cultures are invariably positive. E. coli is the most frequently identified pathogen; Klebsiella and Proteus are less common. The mortality rate is 60-75% with antibiotic therapy and 21-29% after antibiotic treatment and nephrectomy. When this infection extends into the perinephric space, the mortality rate increases sharply to 80%; the overall mortality is 43%. 
The pathogenesis is poorly understood. It has been postulated that the high tissue glucose levels provide a substrate for microorganisms such as E. coli, which are able to produce carbon dioxide by fermentation of sugar. Therefore, EPN should be considered as a complication of severe pyelonephritis rather than a distinct entity. Diagnosis of EPN is usually established radiologically; the hallmark is the intraparenchymal gas. Plain radiographs are good to depict air, which appears as mottled gas shadows over the involved kidney; however, it is often mistaken for bowel gas. Ultrasonography usually demonstrates strong focal echoes, which suggest the presence of intraparenchymal gas. 
Excretory urography is rarely of value, because the affected kidney is usually non functioning or poorly functioning. The CT is the imaging procedure of choice to determine the extent of infection and guide management. Obstruction is revealed in around 25% of the cases. In our case, the cause of obstruction could be papillary necrosis or obstruction by tissue debris, which passed off spontaneously with relief of obstruction. Contrast CT is not recommended in the acute disease due to compromised renal reserve, and functional assessment is not required in the presence of active infection.
Two types of EPN are identified; type I EPN is characterized by parenchymal destruction with either absence of fluid collection or presence of streaky or mottled gas, while Type II EPN is characterized by renal or perirenal fluid collections with bubbly or loculated gas, or gas in the collecting system. The mortality rate for type I EPN is higher (69%) than that for type II (18%). 
EPN is also classified according to the extent of gas invasion and kidneys involvement as class 1: gas confined to collecting system; class 2: gas confined to renal parenchyma; class 3a: extension of gas to perinephric space; class 3b: extension of gas to pararenal space; class 4: bilateral or solitary kidney with EPN. 
Emphysematous pyelonephritis is a surgical emergency. Management of EPN has evolved from aggressive surgical intervention to conservative management such as parenteral antibiotics and fluid resuscitation. Percutaneous drainage or D-J stenting is recommended in case the kidney was obstructed. Thrombocytopenia, shock, altered sensorium and renal function impairment are poor prognostic factors. If the above measures fail or there is worsening of the general condition, an emergency nephrectomy should be considered; if the patient's condition improves nephrectomy can be deferred. Nuclear scan should be done after 3-4 weeks in the patients managed conservatively to evaluate the functional status of the kidney.
Although there are reports of recovery of renal function after medical therapy combined with relief of obstruction, yet most of the patient's require nephrectomy. 
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