What is the management for a patient with impaired renal function and decreased urine output following right Percutaneous Nephrolithotomy (PCNL) and left Retrograde Intrarenal Surgery (RIRS)?

Management of Rising Creatinine and Decreased Urine Output Post-PCNL and RIRS

Immediate bilateral urinary drainage via nephrostomy tubes or ureteral stents is mandatory in this clinical scenario, as obstructing pathology with declining renal function requires urgent decompression to prevent irreversible kidney injury and sepsis. 1

Immediate Assessment and Intervention

Urgent Drainage Required

• Patients with obstructing pathology and declining renal function must undergo urgent collecting system drainage to prevent progression to acute kidney injury and allow recovery of renal function 1
• The choice between percutaneous nephrostomy (PCN) and retrograde ureteral stenting depends on several factors, but both are equally appropriate in this setting 1
• If infection is suspected (fever, leukocytosis), drainage becomes even more critical as infected obstructed systems can rapidly progress to urosepsis 1

Evaluate for Bilateral Obstruction

• Post-operative bilateral procedures (right PCNL, left RIRS) create risk for bilateral collecting system compromise from edema, blood clots, or stone fragments 1
• Obtain urgent renal ultrasound or non-contrast CT to assess for hydronephrosis bilaterally 1
• Rising creatinine with decreased urine output suggests inadequate drainage from one or both kidneys 1

Drainage Strategy Selection

Percutaneous Nephrostomy (PCN)

• PCN is preferred when:
  • Patient is hemodynamically unstable or septic 1
  • Larger bore drainage is needed for blood clots or debris 1
  • Patient is high anesthesia risk 1
  • Pyonephrosis is suspected 1
• Technical success approaches 100% for dilated collecting systems 1
• Allows for subsequent antegrade procedures if needed 1

Retrograde Ureteral Stenting

• Retrograde stenting is appropriate when:
  • Patient is stable without signs of sepsis 1
  • Anatomy allows safe retrograde access 1
  • Avoiding external drainage is preferred for patient comfort 1
• May have higher urosepsis risk in extrinsic obstruction compared to PCN 1
• In the setting of obstructing stones with suspected infection, both PCN and stenting are acceptable, though stenting may result in higher fever rates 1

Critical Pitfall: Distinguishing Hemodynamic vs. Intrinsic Renal Injury

Assess Reversibility of Renal Dysfunction

• Hemodynamic-related GFR decline (from obstruction, edema) is potentially reversible with drainage, while intrinsic tubular injury may not be 1
• Post-PCNL, estimated GFR typically reaches its nadir at 48 hours, then gradually improves 2
• Check urinalysis for:
  • Hematuria, cellular casts, or acanthocytes suggesting intrinsic kidney disease 1
  • Proteinuria/albuminuria indicating glomerular injury (less reversible) 1
• Rising creatinine during decongestion/drainage does not necessarily indicate poor prognosis if related to hemodynamics 1

Monitor for Fluid Absorption Complications

• Both PCNL and RIRS involve high-pressure irrigation that can cause significant fluid absorption (20-573 mL for RIRS, 13-364 mL for PCNL) 3
• Absorbed irrigation fluid can contribute to volume overload and electrolyte abnormalities 3
• Only normal saline should be used for irrigation to prevent hemolysis and electrolyte disturbances 1

Post-Drainage Management

Immediate Post-Procedure Monitoring

• Measure serum creatinine at 6,24,48, and 72 hours after drainage to track recovery trajectory 2
• Monitor urine output from drainage tubes/bladder catheter separately to assess function of each kidney 1
• Avoid nephrotoxic agents, contrast studies, and repeat procedures during the first 48-72 hours when GFR is at its lowest 2

Assess for Complications

• Obtain chest radiograph to evaluate for pleural effusion, which occurs in up to 15% of supracostal PCNL cases 4
• Monitor for signs of SIRS/sepsis from fluid absorption or infected obstruction 3
• Check hemoglobin for bleeding complications 5, 6

Criteria for Successful Drainage

• Urine output should improve within 24-48 hours of adequate drainage 1
• Creatinine should stabilize or begin declining by 48-72 hours 1, 2
• If creatinine continues rising despite bilateral drainage, consider:
  • Inadequate decompression requiring tube repositioning 1
  • Intrinsic acute tubular necrosis from prolonged obstruction 1
  • Ongoing sepsis requiring broader management 1

When to Consider Renal Replacement Therapy

Indications for Dialysis

• Renal replacement therapy is indicated for stage 3 AKI (creatinine ≥3x baseline or requiring dialysis) 1
• Severe electrolyte abnormalities, volume overload, or uremic symptoms despite drainage 1
• Urine output <0.5 mL/kg/hr for >6 hours despite adequate drainage suggests need for RRT consideration 1

Timing of RRT Discontinuation

• Once drainage is established and kidney function recovers, RRT can be discontinued when urine output exceeds 400-500 mL/24h (though optimal thresholds vary widely from 191-1720 mL/24h across studies) 1
• Diuretic challenge may help predict successful RRT discontinuation, though evidence is mixed 1