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Asymptomatic emphysematous pyelitis—a rare clinical entity
  1. Hannah Thorman,
  2. Nikita R Bhatt,
  3. Sona Kapoor and
  4. Azad Hawizy
  1. Urology Department, Ipswich Hospital, Ipswich, UK
  1. Correspondence to Hannah Thorman; h.thorman{at}


A 62-year-old asymptomatic woman with diabetes was referred to the urology department from nephrology due to deterioration in renal function with accompanied right-sided hydronephrosis on ultrasound. CT imaging subsequently revealed a right-sided staghorn calculus and a significant volume of gas in the right collecting system from the kidney to the distal ureter, in keeping with emphysematous pyelitis. She was admitted and managed with antibiotics and insertion of right nephrostomy in the first instance, followed by percutaneous nephrolithotomy to definitively manage the stone. The patient remained asymptomatic throughout the process.

  • urinary tract infections
  • acute renal failure
  • gas/free gas
  • urology

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Emphysematous pyelitis is a rare condition which is characterised by the presence of gas confined to the renal excretory system.1 It is more common in those with diabetes mellitus and may be associated with urolithiasis. Clinical presentation usually includes abdominal pain, dysuria, haematuria or fever. We present a case of emphysematous pyelitis diagnosed in an asymptomatic patient with diabetes with deteriorating renal function.

Case presentation

An asymptomatic 62-year-old woman was referred to nephrology due to gradually declining renal function with a serum creatinine of 113 μmol/L and estimated glomerular filtration rate (eGFR) 45 mL/min. Her baseline creatinine was 72 μmol/L and eGFR was 93 mL/min. Her medical history includes type 2 diabetes mellitus, anaemia, ischaemic heart disease and high triglycerides. Her full blood count, bone profile and liver function tests were unremarkable. An ultrasound scan of the urinary tract revealed right-sided hydronephrosis with multiple renal calculi. She was subsequently referred to urology and a CT scan of the urinary tract was performed to investigate the cause of hydronephrosis. This showed a staghorn calculus extending up to the right pelvi-ureteric junction (figures 1 and 2). It also demonstrated a significant volume of gas in the collecting system of the right kidney, with absence of gas in the renal parenchyma, therefore in keeping with a diagnosis of emphysematous pyelitis.

Figure 1

Coronal view of CT scan of the urinary tract.

Figure 2

Axial view of CT scan of the urinary tract.

The CT scan findings prompted concern that the patient could become acutely unwell with a possible risk of sepsis if not promptly managed, she was therefore referred to the on-call urology team for admission and further assessment. She was asymptomatic, her vital signs and clinical examination were unremarkable. On admission she had a creatinine of 155 μmol/L and eGFR 31 mL/min. Blood inflammatory markers were normal. Urine was sent for microscopy and culture which grew a multidrug resistant Escherichia coli, only sensitive to trimethoprim and pivmecillinam. It was resistant to co-amoxiclav, amoxicillin, cefalexin and nitrofurantoin. She was commenced on pivmecillinam and a right nephrostomy was inserted due to infection in the presence of obstruction. Following this her renal function improved and she was discharged home.

Outcome and follow-up

Her case was discussed at the multidisciplinary team meeting and the decision was made to offer percutaneous nephrolithotomy to treat her stone. She has subsequently undergone this procedure and is stone free. Her nephrostomy was successfully clamped and removed postoperatively. Her renal function improved postoperatively to a creatinine of 111 μmol/L and eGFR 46 mL/min. She is due to be followed up in the urology outpatient department 6 months postoperatively for further review and an X-ray of the urinary tract.


Emphysematous urinary infections are caused by gas-forming organisms and can be classified according to the distribution of gas in the urinary tract.1 Emphysematous pyelitis is a rare infection in which gas is confined to the renal-collecting system. It should be distinguished from emphysematous pyelonephritis, defined as the presence of gas in the renal parenchyma. This distinction is important due to variation in management approach and prognosis. Emphysematous pyelonephritis is associated with a 50% mortality, in comparison with up to 20% in emphysematous pyelitis.2

Approximately 50% of cases of emphysematous pyelitis are associated with diabetes mellitus.1 Other risk factors include urinary tract obstruction, of which calculi are the most common cause. The majority of patients present with a combination of abdominal pain, fever or symptoms of urinary tract infection, such as dysuria or haematuria (table 1). In the case we present, the patient was asymptomatic and clinical examination was unremarkable, so the patient was investigated for a declining renal function.

Table 1

Clinical presentation of emphysematous pyelitis as reported in previous literature1 2 5 7–20

Organisms most commonly associated with emphysematous pyelitis include E. coli, Klebsiella, Proteus mirabilis and Aerobacter.2 3

CT is the imaging modality of choice for diagnosis of emphysematous urinary tract infections.3 It allows differentiation of emphysematous pyelitis from emphysematous pyelonephritis and enables identification of any associated obstruction.

Huang and Tseng divided emphysematous pyelonephritis into four different classes (table 2).4 Class I describes emphysematous pyelitis, where gas is confined to the collecting system. In class II gas is located in the renal parenchyma without extension into the extrarenal space. Class IIIa and class IIIb refer to gas extending into the perinephric and pararenal space, respectively. Class IV is reserved for emphysematous pyelonephritis which is bilateral or affecting a solitary kidney.

Table 2

Huang and Tseng classification of emphysematous pyelonephritis4

Management is dependent on the above classification. Recommended treatment for patients with class I infection (emphysematous pyelitis) depends on the presence of urinary tract obstruction.4 In uncomplicated cases, broad spectrum antibiotics alone appear to provide adequate treatment.5 However, if complications such as abscess formation or obstruction are present, then percutaneous drainage is required in addition.6 In this case, the patient was managed with antibiotics and right nephrostomy insertion initially, followed by definitive procedure for the stone.

Hence, though uncommon, our case highlights the rare asymptomatic presentation of emphysematous pyelitis, a condition with a 20% mortality. Declining renal function in a patient with diabetes was appropriately investigated leading to a prompt diagnosis and management of this condition, ensuring a favourable outcome.

Learning points

  • Asymptomatic emphysematous pyelitis is rare with only one other reported case in the literature.

  • Emphysematous pyelitis is more prevalent in diabetics.

  • Initiate prompt management of emphysematous pyelitis to reduce risk of associated morbidity and mortality.

  • Significant deterioration in renal function should be thoroughly investigated.



  • Contributors AH was the responsible clinician for the patient. HT produced the initial draft. HT, NRB, SK and AH edited subsequent drafts and all approved the final manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.