Emergency Medicine · Year 3 · from Emergency Medicine

Case 2: Obstructed Infected Kidney (Pyonephrosis)

Patient Demographics

  • Age: 54 years
  • Sex: Female
  • Occupation: Office manager

Chief Complaint

"I have terrible pain in my right side and I've been shaking with chills."

History of Present Illness

The patient presents with 2 days of progressively worsening right flank pain, now severe and constant, rated 10/10. She initially thought she had another kidney stone, as she has a history of calcium oxalate nephrolithiasis with two prior episodes. The pain was initially colicky but has become constant over the past 24 hours. She developed fever and rigors last night and has been unable to keep any food or fluids down due to nausea and vomiting. She reports dysuria and urinary frequency over the past several days. Her last kidney stone was 2 years ago and passed spontaneously after several days. She has no history of diabetes or immunocompromise.

Vital Signs

  • Temperature: 103.4 degrees F (39.7 degrees C)
  • Blood pressure: 92/58 mmHg
  • Heart rate: 118 bpm
  • Respiratory rate: 22/min
  • Oxygen saturation: 94% on room air

Physical Examination

General: Ill-appearing woman, diaphoretic, rigors observed during examination Cardiovascular: Tachycardic, regular rhythm, no murmurs Pulmonary: Clear to auscultation bilaterally, tachypneic Abdomen: Soft, mild right lower quadrant tenderness, no peritoneal signs Back: Severe right costovertebral angle tenderness Skin: Warm, flushed, no rashes

Laboratory Findings

  • WBC: 24,500/microL with 88% neutrophils and 8% bands (left shift)
  • Hemoglobin: 13.2 g/dL
  • Platelets: 168,000/microL
  • Sodium: 136 mEq/L
  • Potassium: 4.1 mEq/L
  • BUN: 32 mg/dL
  • Creatinine: 1.8 mg/dL (baseline 0.9)
  • Lactate: 4.2 mmol/L
  • Urinalysis: Cloudy, large leukocyte esterase, positive nitrites, >100 WBCs/HPF, many bacteria

Imaging

Non-Contrast CT Abdomen/Pelvis:

  • 9 mm obstructing stone at the right ureterovesical junction
  • Moderate right-sided hydronephrosis with perinephric fat stranding
  • Urothelial thickening suggesting pyelonephritis
  • No evidence of abscess formation

Diagnosis

Obstructed infected kidney (pyonephrosis) - urologic emergency requiring emergent decompression

  • Urosepsis with septic shock
  • Obstructing right ureteral stone

Management

Sepsis Resuscitation:

  1. Large-bore IV access x2, aggressive crystalloid resuscitation (30 mL/kg bolus)
  2. Blood cultures x2 obtained
  3. Urine culture obtained
  4. Broad-spectrum IV antibiotics: Piperacillin-tazobactam 4.5 g IV
  5. Foley catheter placed for urine output monitoring
  6. Arterial line placed for continuous blood pressure monitoring
  7. Norepinephrine initiated for persistent hypotension after 2L fluid resuscitation

Emergent Urologic Intervention:

  1. Emergent urology consultation
  2. Decision for emergent ureteral stent placement versus percutaneous nephrostomy
  3. Patient taken to cystoscopy suite for retrograde ureteral stent placement
  4. Grossly purulent urine drained upon stent placement
  5. Successful decompression achieved

Post-Procedure Management:

  • Admitted to ICU
  • Vasopressors weaned off within 24 hours
  • Blood cultures grew Escherichia coli
  • Urine culture grew E. coli >100,000 CFU/mL
  • Antibiotics narrowed to ceftriaxone based on sensitivities
  • Creatinine improved to 1.1 by day 3
  • Stone management deferred until infection resolved

Clinical Pearl

The combination of urinary obstruction and infection creates a closed-space infection that can rapidly progress to septic shock and death. This is one of the few urologic emergencies where emergent intervention (ureteral stent or percutaneous nephrostomy) is required regardless of time of day. Neither antibiotics nor fluid resuscitation alone will adequately treat this condition without decompression. The stone itself is addressed electively after the infection has resolved, typically 4-6 weeks later.

Clinical Image

Image Description: Non-contrast CT scan of the abdomen demonstrating moderate hydronephrosis with an obstructing ureteral stone at the ureterovesical junction and perinephric fat stranding indicating inflammation.

Attribution: Image from Wikimedia Commons, Category: CT images of hydronephrosis. Licensed under CC BY-SA 3.0. Source: https://commons.wikimedia.org/wiki/Category:CT_images_of_hydronephrosis

All cases for this lecture as Markdown