A patient who had a ureteral stent placed for kidney stones removed today now presents with sudden severe ipsilateral flank pain briefly relieved after passing a blood clot, leukocytosis with neutrophil predominance, and impaired renal function (eGFR ~46 mL/min, creatinine 139 µmol/L). What is the appropriate immediate management?

Immediate Management of Post-Stent Removal Complications with Leukocytosis and Renal Impairment

This patient requires urgent imaging with contrast-enhanced CT urography and immediate broad-spectrum IV antibiotics (ceftriaxone 1-2g daily), with strong consideration for emergent urinary decompression via percutaneous nephrostomy or retrograde ureteral stenting if imaging reveals obstruction, perinephric stranding, or abscess formation. 1, 2

Clinical Interpretation

Your patient presents with a constellation of findings highly concerning for obstructive pyelonephritis or pyonephrosis:

• Leukocytosis (WBC 14.3) with neutrophil predominance (12.1) indicates high probability of bacterial infection, with a likelihood ratio of 3.7 for documented infection even without fever 2
• Acute severe flank pain (10/10) that transiently improved after passing a blood clot suggests either:
  • Clot obstruction of the ureter that temporarily relieved when passed, OR
  • Ongoing bleeding with potential re-obstruction
• Impaired renal function (eGFR 46, creatinine 139 µmol/L) in the context of recent instrumentation raises concern for obstruction or infection-related acute kidney injury 3

Urgent Diagnostic Work-Up

Immediate Laboratory Studies

• Obtain blood cultures (minimum two sets) and urine culture BEFORE starting antibiotics to identify causative pathogens and guide definitive therapy 1
• The combination of leukocytosis and recent stent manipulation creates high risk for urosepsis 3, 2

Imaging Requirements

Contrast-enhanced CT urogram is mandatory as first-line imaging to assess: 1

• Stent position (if any fragment remains) or complete removal
• Presence of perinephric stranding, abscess, or hematoma
• Degree of hydronephrosis
• Residual stone burden or new obstruction
• Any perforation or urinoma formation

Do not postpone imaging when clinical status suggests infection—prompt CT is required to identify correctable anatomic causes such as retained stent fragments, new obstruction, or perinephric collections 1

Immediate Antibiotic Therapy

Start IV ceftriaxone 1-2g daily immediately as first-line empiric therapy—it demonstrates superior clinical and microbiological cure rates compared with fluoroquinolones for obstructive pyelonephritis 2

Preprocedural antibiotics are essential when urosepsis is suspected, as postprocedural bacteremia and sepsis are common when infected urinary tracts are drained 3, 1

Indications for Emergent Urinary Decompression

Percutaneous nephrostomy (PCN) should be instituted without delay if the patient demonstrates: 1, 2

• Sepsis or hemodynamic instability
• Worsening renal function
• Persistent fever despite antibiotics
• CT evidence of:
  • Severe persistent hydronephrosis
  • Perinephric abscess or pyonephrosis
  • Retained stent fragment causing obstruction

PCN provides superior drainage compared to internal stents in pyonephrosis and improves early and long-term cure rates, with patient survival of 92% versus 60% for medical therapy alone 3, 2

Retrograde ureteral stenting is an equivalent alternative if the patient is hemodynamically stable, though prolonged guidewire manipulation can increase urosepsis risk 3, 2

Critical Pitfalls to Avoid

• Antibiotics alone are insufficient in treating acute obstructive pyelonephritis—decompression is essential 2
• Do not delay drainage while awaiting antibiotic effect; obstruction impedes drug delivery to the infected kidney 2
• Close monitoring for worsening sepsis is required immediately intraprocedure and postprocedure, as bacteremia is common when infected urinary tracts are drained 3, 1
• Hematuria lasting >48-72 hours post-stent removal warrants diagnostic evaluation for complications such as obstruction or infection 1

Post-Decompression Management

After infection control and definitive culture results:

• Tailor antimicrobial therapy to sensitivities and continue monitoring until temperature, WBC count, and inflammatory markers normalize 1
• Definitive stone treatment should be delayed until sepsis is resolved and the patient completes a full course of IV antibiotics 2, 4
• Follow-up imaging should verify complete resolution of underlying pathology before considering any further intervention 1

Alternative Diagnosis Considerations

If imaging reveals no obstruction or infection, consider:

• Stent migration (occurs in 5-8% of cases) 3, 5, 6
• Ureteral injury from stent removal (occurs in 6% of cases) 3
• Retained stent fragment causing irritation or bleeding 5, 7

However, given the leukocytosis and neutrophil predominance, infection remains the most likely and dangerous diagnosis requiring immediate action 2