Infection · Hard
This case is fictional and exists for study. It describes no real patient.
58 years · female
A 58-year-old female with a 15-year history of poorly controlled type 2 diabetes mellitus presents to the emergency department with a 3-day history of worsening left flank pain, high-grade fevers, rigors, dysuria, and nausea. Over the past 12 hours, her family noted marked lethargy and confusion. On physical examination, she appears acutely ill, toxic, and confused. Marked left costovertebral angle tenderness is present on palpation, along with mild lower abdominal tenderness without guarding or rebound. Capillary blood glucose on arrival is 18.2 mmol/L. Intravenous access is established, and aggressive crystalloid fluid resuscitation is initiated.
Vital signs
- HR
- 118 bpm
- BP
- 88/54 mmHg
- RR
- 24/min
- Temp
- 39.1 °C
- SpO₂
- 94%
Examination findings
- Acutes ill appearance with dry mucous membranes
- Severe left costovertebral angle tenderness
- GCS 13 (E3 V4 M6)
Investigations
| Haemoglobin | 11.2 g/dL | reference: 12.0-15.5 |
| White blood cell count | 21.5 10^9/L | reference: 4.0-11.0 |
| Platelets | 110 10^9/L | reference: 150-400 |
| Serum creatinine | 185 µmol/L | reference: 44-80 |
| Urea | 14.2 mmol/L | reference: 2.5-7.8 |
| C-reactive protein | 210 mg/L | reference: < 5 |
Question 1 of 3
Which of the following is the most appropriate next diagnostic imaging investigation for this patient?
Non-contrast CT of the abdomen and pelvis is the primary diagnostic imaging modality of choice for suspected emphysematous pyelonephritis, renal abscess, or complex urolithiasis in diabetic patients with severe complicated pyelonephritis or urosepsis. CT has high sensitivity for detecting parenchymal gas, extent of infection, and anatomical obstruction. Renal ultrasound (Option C) can miss early parenchymal gas and retroperitoneal involvement due to acoustic shadowing from bowel gas. Intravenous urography (Option D) is obsolete in acute settings and carries a risk of contrast-induced nephropathy in acute kidney injury. MRI (Option A) is impractical, time-consuming, and unsuitable in an unstable, acutely septic patient.
Teaching point: Non-contrast CT scan of the abdomen and pelvis is the modality of choice for identifying emphysematous pyelonephritis in high-risk diabetic patients.
Question 2 of 3
CT imaging reveals gas within the left renal parenchyma and perinephric tissue without urinary tract obstruction. What is the most likely diagnosis?
The presence of gas within the renal parenchyma and perinephric space in a patient with poorly controlled diabetes presenting in septic shock is diagnostic of emphysematous pyelonephritis. Uncomplicated acute pyelonephritis (Option A) presents without tissue necrosis or gas formation on imaging. Xanthogranulomatous pyelonephritis (Option C) is a chronic granulomatous destructive process usually associated with long-standing staghorn calculi, not acute parenchymal gas accumulation. Emphysematous cystitis (Option D) is characterized by gas restricted to the urinary bladder wall or lumen without renal involvement.
Teaching point: Emphysematous pyelonephritis is a life-threatening necrotizing renal infection characterized by gas in the renal parenchyma, occurring primarily in individuals with diabetes.
Question 3 of 3
Alongside intravenous fluid resuscitation and broad-spectrum intravenous antimicrobial therapy, what is the most appropriate next step in definitive management?
Definitive management for emphysematous pyelonephritis combines intravenous antibiotics, glycaemic control, fluid resuscitation, and early percutaneous catheter drainage (PCD) by interventional radiology or urology. PCD preserves renal function and significantly reduces mortality compared to medical therapy alone or immediate nephrectomy. Immediate open nephrectomy (Option B) carries high surgical mortality in septic patients and is reserved for cases where percutaneous drainage fails. Delaying intervention for 48 hours (Option A) leads to high mortality in septic shock. Ureteric stenting (Option C) is beneficial for obstructing urinary calculi, but non-obstructed emphysematous pyelonephritis requires direct drainage of parenchymal gas/fluid collections.
Teaching point: Percutaneous catheter drainage combined with broad-spectrum intravenous antibiotics is the preferred initial treatment for emphysematous pyelonephritis.
Key learning points
- Emphysematous pyelonephritis is a severe, gas-forming necrotizing infection of the renal parenchyma occurring mostly in poorly controlled diabetes.
- Non-contrast CT scan of the abdomen and pelvis is the gold standard investigation to confirm the presence and extent of renal parenchymal gas.
- First-line management requires prompt fluid resuscitation, empirical parenteral broad-spectrum antibiotics, glycaemic control, and percutaneous catheter drainage.
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