Last updated: Lesson of the Month - October 2017…
on 17 Oct 2017

June 2013

Timothy Evans MRCS and Yogita Aggarwal MRCP


A 21 year old female diabetic was admitted acutely to ED with severe left sided abdominal and flank pain, pyrexia and generalised systemic upset.  Her symptoms had started gradually some 18 hours earlier but had deteriorated quickly over the few hours preceding presentation. On arrival in the emergency department she had the following baseline observations:

  1. Temp: 38.2
  2. Pulse: 130 sinus tachycardia
  3. BP: 80/50
  4. General Appearance:  Vasodilated and rolling around in pain.
  5. Venous acid-base: Normal acid-base and a lactate of 2.4

The patient received aggressive fluid resuscitation and intravenous morphine analgesia. An initial working diagnosis of an acute surgical abdomen was raised; and urgent surgical and medical opinions were requested.

Her past medical history was obtained from electronic records and it was discovered that the patient had had a neonatal partial pancreatectomy (although she could not remember why she had required this) but she had been diabetic since and over the last 5 years had HBA1c readings of over 15% (Normal 6-7%). Her BMs were frequently over 25 and often over 30. She also had a history of recurrent lower urinary tract infections and saw her GP for ‘monthly’ antibiotics. No urine cultures were available on electronic records, but she did recount episodes of left and right sided pyelonephritis 3-4 times a year which had not always required hospital admission. She was not under any renal or urological follow-up.

She had also had a prolonged ITU admission a few months earlier having presented with a fully-sensitive Escherichia coli septicaemia with pneumonic changes and multi-organ failure requiring invasive ventilation, inotropic support and haemofiltration. Abdominal imaging at the time had shown no acute abnormalities, and two normal sized kidneys containing bilateral parenchymal scarring. The E.coli had only been grown in blood cultures – there had been a delay in sending urine for culture following initiation of antibiotics.

Assessment in the emergency department by the medical and surgical teams (after analgesia) confirmed the patient’s pain was localised to her left renal angle, however the intensity of her pain was out of keeping with the typical presentation of an acute uncomplicated pyelonephritis. She denied any lower urinary tract symptoms and her last course of antibiotics had been some 4 weeks earlier. Her pregnancy test was negative and the urine dipstix showed:

  1. +ve nitrites
  2. 2+ leucocytes                                 
  3. 2+protein
  4. 3+ blood
  5. 3+ glucose
  6. 1+ ketones

Historical notes revealed that the urine usually contained a trace of protein only.The patient also complained of subjective hypoparaesthesia of her left entire leg. There was no evidence of any objective neurological or vascular abnormality.

Given the intensity of the patient’s pain, recurrent nature of ascending renal infections, poorly controlled diabetes and altered left leg sensorium, urgent imaging was requested with particular interest to the patient’s left retroperitoneal space.  A CT was advised by the surgical team, and as the patient was stabilising with fluids and appropriate antibiotics, a decision was made to wait for the UEs before proceeding to contrast administration.

Her blood tests showed an acute kidney injury in the presence of infection:

  1. Na - 140           
  2. K - 5.6
  3. Urea - 15 (baseline 4)
  4. Creat - 224 (baseline 80)
  5. Hb - 15
  6. Plat - 600
  7. INR - 1.4
  8. WCC - 28 (>70% neutrophilia)
  9. CRP - 150
  10. Glucose 22
  11. Serum Ketone 1.0 (normal < 1.5)
  12. HBA1c  15%
  13. LFTs - normal with mild hypoalbunminaemia

Clinically the patient was septic and given the blood picture the working diagnosis was that the patient had a left complicated pyelonephritis secondary to some form of obstruction. Urgent imaging +/- radiological urological intervention was requested. A non-contrast CT was arranged (given the degree of acute renal impairment):

The arrow points to the left kidney, which is much larger than the normal right kidney due to air and inflammation. The black pockets (highlighted by the white dots) are air which are in the kidney and track into the ureter. These are abnormal findings. There is also peri-nephric fat stranding around the left kidney, suggesting inflammation.

The patient was discussed with the on call microbiologist as typically (for emphysematous pyelonephritis) broader antibiotic cover is required – usually gram negative, positive and anaerobic. The patient was also discussed with the on call urology and interventional radiology teams. She had a decompression nephrostomy in-situ within 5 hours of coming into ED and was then transferred to HDU under joint urology and diabetology care.

The nephrostomy drained pus. On this admission, blood, urine and pus cultures grew a fully sensitive E.coli. She had a nephrostogram which showed a mid-ureteric stenosis thought to be due to either a stricture or debris. After more than a week of IV antibiotics, whilst being infection free the patient had a ureteric stent inserted and was discharged home with a creatinine at her baseline.

Her follow-up included robust DM and renal management. Better control of her diabetes was essential in reducing stent bacterial colonisation and secondary infections.


Emphysematous pyelonephritis (EPN) is a severe necrotising infection of the renal parenchyma.  It causes gas formation within the collecting system, renal parenchyma, and/or peri-renal tissues. EPN is common in diabetics, and can present similar to an acute pyelonephritis but the clinical course of EPN can be severe and life-threatening if not recognized and treated promptly[i]. Altered consciousness, altered sensorium, multiple organ failure, hyperglycaemia, and elevated leukocyte count were all indicators of a poor prognosis. Associated mortality can be over 11%. [ii] The commonest organisms are Escherichia coli (in 66%), Klebsiella (in 26%), Proteus, Pseudomonas, and Streptococcus.

The severity of EPN is related to the extent of emphysematous tracking.  It can be unilateral or bilateral, and involve the ureters and bladder.  The key points in the management are focused on the emergency decompression of the infected collecting systems and broad spectrum antimicrobial cover.  Patients require intensive, and often invasive, monitoring during their recovery.  Urological opinion should be sought early as nephrectomy may be indicated, based on the extent of spread and the patient’s response to initial management.

Learning points from this case:

  1. Pain disproportionate to the expected clinical presentation should be alarming to the presence of other pathology.
  2. Poor diabetic control – worse outcome in sepsis and infection. They also deteriorate quickly.
  3. VBG and lactate did not demonstrate how sick the patient was and thus can be falsely reassuring regarding the level of sepsis on board – trust clinical the signs and your intuition.
  4. A rise in creatinine is a separate indicator for urgent imaging. An obstructed infected renal system is a renal/urological emergency and needs urgent decompressive radiological or urological intervention.
  5. Broad-spectrum antibiotic cover to include gram positive, gram negative and anaerobic cover: a suggested regime is gentamicin, ampicillin (vancomycin if pencillin allergic) and metronidazole.
  6. Close monitoring of patient and renal function – often an HDU bed is required.  A close eye on sepsis as it can progress to requiring a nephrectomy.
  7. Patient already has CKD, most likely secondary to diabetes.  Further, the patient had a BMI of 18, and given her muscle mass, the baseline creatinine of 84 was too high and an estimated value should have been around 60.

EPN has a migh mortality in the event of late diagnosis. Often a high index of suspicion is required to make a timely diagnosis. In this case the team managed the patient extremely well with appropriate imaging and out of hours intervention to relieve the obstructed, infected renal tract. A late diagnosis could have been potentially fatal. The key lesson here is to trust your clinical judgment and have a low threshold for imaging in suspected cases of EPN.

Shetty S. Emphysematous Pyelonephritis - E-Medicine - Medscape

Olvera-Posada D, García-Mora A, Culebro-García C, et al. Prognostic Factors in Emphysematous Pyelonephritis. Actas Urol Esp. Dec 19 2012

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