Emphysematous Pyelonephritis

NYU Case of the Month, October 2019

Case of the Month Emphysematous Pyelonephritis NYU Case of the Month, October 2019 Frederick A. Gulmi, MD Vice Chair of Urology, NYU School of Medicine, New York, NY; Chief of Urology, NYU Langone Hospital—Brooklyn, Brooklyn, NY [Rev Urol. 2019;21(4):175–177] © 2020 MedReviews®, LLC A 64-year-old woman with a history of kidney stones status post–multiple procedures for the stones in the past presents to the emergency department (ER) with a chief complaint of abdominal distention, hematuria, nausea, vomiting, and abdominal pain mostly in the right upper quadrant for the past 2 days. She was also experiencing fever and chills for a day before her presentation to the ER. Past Medical History: Diabetes mellitus, hypertension, kidney stones, hyperlipidemia Past Surgical History: Extracorporeal shockwave lithotripsy (ESWL), ureteroscopy with laser lithotripsy 3 2, ureteral stent placement, cesarean delivery 3 2, total abdominal hysterectomy Smoking History: Smoking 1 pack per day for 20 years Review of Systems: Not contributory Physical Examination Temperature, 36.70 C; heart rate, 78; respiration, 20; BP, 88/48 mm Hg; constitution, no acute distress, not diaphoretic and appears ill Abdomen, distended with tenderness in the right upper quadrant; no masses and no organomegaly Back, positive for right CVA tenderness Neurologic, alert and oriented 3 3; moving all four extremities with good strength Laboratory Data Complete Blood Count with Differential: WBC, 13.8 3 103/uL; Hemoglobin, 11.6 g/dL; Hematocrit, 34%; Platelet count, 118,000/uL with shift to the left on differential with neutrophils % at 94. Comprehensive Metabolic Panel: Sodium, 126 mmol/L; Potassium, 4.2 mmol/L; Chloride, 95 mmol/L; Carbon dioxide, 24 mmol/L; Blood urea nitrogen, 71mg/dL; Creatinine, 1.950 mg/dL; Glucose, 451 mg/dL; Albumin, 2.1 g/dL; eGFR MDRD, 26 mL/min/1.73 m2 Venous Blood Gas: Venous pH, 7.472; Venous PCO2, 28.7 mm Hg; Venous PO2, 34 mm Hg; Venous HCO3, 21 mmol/L; Base deficit, 3 mmol/L; Venous SO2 calculated, 70%; Venous TCO2 calculated, 22 mmol/L; Venous lactate, 2.84 mmol/L Urinalysis: pH, 5.5; Specific gravity, 1.022; WBC, loaded; Bacteria, many; RBC, 10; HPF blood culture, Escherichia coli 3 2 bottles submitted Urine Culture: E coli . 100,000 CFU/mL; Klebsiella pneumoniae . 100,000 CFU/mL Imaging CT scan of the abdomen and pelvis demonstrated a large volume of gas in the upper-midpole right kidney consistent with emphysematous pyelonephritis. There are several radiopaque intrarenal calculi and a few proximal right ureteral calculi measuring up to 7 mm without hydronephrosis and mild mural wall thickening of the proximal right ureter with trace gas within the proximal collecting system consistent with Vol. 21 No. 4 • 2019 • Reviews in Urology • 175 Emphysematous Pyelonephritis continued A B C Figure 1. (a) Initial axial image of the CT scan of the abdomen and pelvis upon presentation the emergency room demonstrating multiple pockets of intrarenal air in the medial and lateral midportion of the right kidney. (b) Initial coronal image of the CT scan of the abdomen and pelvis upon presentation the emergency room demonstrating multiple pockets of intrarenal air in the medial upper pole and lateral midportion of the right kidney. (c) Initial coronal image of the CT scan of the abdomen and pelvis upon presentation the emergency room demonstrating air in the collecting system with several intrarenal stones of the right kidney. emphysematous pyelitis. Mild reactive right perinephric/periureteral fat stranding. The left kidney was normal, with no calculi or hydronephrosis (Figure 1). Management The patient was admitted to the hospital and given IV fluid resuscitation and antibiotics. She underwent emergent cystoscopy and placement of a ureteral double J stent. The patient was then admitted to the SICU. She was maintained on IV piperacillin/tazobactam. The patient’s overall condition improved; however, on hospital day 3, she began spiking fever again to 101.12°F, with a heart rate of 102 and an increase in her WBC count from 7.8 to 18.4 3 103 /uL. A repeat CT scan of the abdomen and pelvis again demonstrated multiple air and fluid containing abscesses in the renal parenchyma with some increase in their size (Figure 2). Interventional radiology was consulted, and two percutaneous drains were placed (Figure 3). The patient improved clinically but continued to have low-grade fevers of 99.9°F and interventional radiology drained the third collection by needle aspiration. A nuclear renal Figure 2. Coronal image of the CT scan of the abdomen and pelvis repeated demonstrating multiple pockets of intrarenal air in the medial upper pole and lateral midportion of the right kidney now with air fluid level and increase in size. Figure 3. Axial image of the CT scan of the abdomen and pelvis with percutaneous drains in place with decompression of the intrarenal air and abscess size. 176 • Vol. 21 No. 4 • 2019 • Reviews in Urology scan ordered by nephrology demonstrated 30% overall renal function by the right kidney. The patient remained on IV antibiotics and was discharged home on hospital day 14 after the removal of one renal drain. IV antibiotics were administered for a total of 28 days. The second drain was removed 23 days after placement. A repeat CT scan of the abdomen and pelvis 25 days after the admission showed resolution of the renal abscesses (Figure 4). The patient underwent successful ureteroscopy and stone fragmentation 1 month after her initial presentation. Figure 4. Axial image of the CT scan of the abdomen and pelvis with percutaneous drains removed demonstrating complete resolution of the intrarenal air and abscess cavities. Emphysematous Pyelonephritis Discussion Emphysematous pyelonephritis (EPN) is a necrotizing urinary tract infection that can be life threatening. It has been defined as an acute infection of the renal parenchyma and peri-renal tissue resulting in gas within the renal collecting system, parenchyma, or perinephric tissue.1,2 It is more prevalent in patients that are diabetic or immunocompromised with a female to male predominance of 4:1 and a mean age range of 57 years (range, 24-83).1,2 Historically, the mortality rate approached 50% in patients with EPN. However, with more recent treatment approaches as outlined by classification of the ENP and management according to this classification, the mortality has been reduced to 18%.1 Initially, a patient’s medical management should include antibiotics, fluid resuscitation, and control of blood sugar. The extent of the disease needs classification according to the CT images based on the Huang and Tseng3 classification system: Class I: Gas in the collecting system only Class II: Parenchymal gas only Class IIIa: Extension of the gas into the perinephric space Class IIIb: Extension of the gas into the pararenal space Class IV: solitary kidney or bilateral disease In mild cases of EPN (Class I and II), the management can be conservative with relief of any urinary obstruction by placement of a ureteral stent. This patient initially was Class II and was initially managed with a ureteral stent and IV antibiotics. Placement of a nephrostomy tube instead of a ureteral stent is acceptable. However, the patient initially improved and then deteriorated clinically with persistent fevers and an elevation of the WBC count. This prompted more aggressive treatment with percutaneous drainage. If the patient fails to respond to initial conservative treatment in Class I and II EPN or has a more severe case of EPN, then more aggressive treatment with percutaneous drainage should be performed. If the percutaneous drainage is not effective, then open drainage should be considered before the patient undergoes an emergency nephrectomy. This has been shown to lower the overall mortality rate. Aboumarzouk and colleagues, in a meta-analysis of 32 reports, showed the mortality of percutaneous drainage with delayed nephrectomy of 10.6%, percutaneous drainage alone of 13.8%, open drainage alone of 6 %, and initial emergency nephrectomy of 33.3%. Risk factors that contributed to the patient’s mortality in this same meta-analysis were urinary obstruction versus no obstruction, shock versus no shock, Huang Classification of Class I and II versus Class III and IV. This means fewer patients with obstruction, no shock, and Class I and II EPN died than those with no obstruction, shock, and Class III and IV EPN. Therefore, patients presenting with shock may need treatment in the ICU with an intensive-care specialist involved for supportive care. References 1. 2. 3. Aboumarzouk OM, Hughes O, Narahari K, et al. Emphysematous pyelonephritis: Time for a management plan with a evidence-based approach. Arab J Urol. 2014;12:106-115. Pontin AR, Barnes RD. Current management of emphysematous pyelonephritis. Nat Rev. Urol. 2009;6:272-279. Huang JJ, Tseng CC. Emphysematous pyelonephritis: clinicoradiologic classification, management, prognosis and pathogenesis. Arch Intern Med. 2000;160:797-805. Vol. 21 No. 4 • 2019 • Reviews in Urology • 177