When is percutaneous nephrostomy (PN) recommended and what are the considerations for the procedure?

Percutaneous Nephrostomy: Indications and Procedural Considerations

Primary Indications

Percutaneous nephrostomy (PCN) is most critically indicated for obstructive uropathy complicated by infection and sepsis, where it reduces mortality from gram-negative septicemia from 40% to 8%. 1

Urgent/Emergent Indications

• Obstructed infected system with sepsis or hypotension - PCN is the procedure of choice when patients appear septic with fever, leukocytosis, and signs of obstructive uropathy 2
• Pyonephrosis - Infected hydronephrosis requires immediate decompression to prevent life-threatening urosepsis 3
• Failed retrograde ureteral stenting - When retrograde approaches cannot be accomplished, PCN provides definitive drainage 2, 4

Elective Indications

• Upper urinary tract obstruction (benign or malignant) when ureteral stent placement is not feasible 2, 4
• Ureteral injuries, leaks, or fistulas - PCN decompression as primary management decreases need for reoperation and reduces morbidity 2
• Renal transplant complications - Post-transplant ureteral leaks, fistulas, strictures, and obstructions 2
• Access for urological procedures - Including percutaneous nephrolithotomy, antegrade pyelography, and delivery of chemotherapeutic agents 2
• Assessment of recoverable renal function - In longstanding obstruction, PCN can predict functional recovery based on renal plasma flow response to decompression 1

Contraindications

The only absolute contraindication is uncorrectable coagulopathy. 5

• Marked coagulopathy or thrombocytopenia must be corrected before all but the most emergent procedures 5
• Relative contraindications should be weighed against the urgency of drainage, particularly in septic patients where mortality risk outweighs procedural risk 1

Pre-Procedural Considerations

Antibiotic Prophylaxis

• Antibiotics should be administered routinely before nephrostomy drainage to minimize risk of sepsis 5
• Choice based on patient-specific risk factors for bacteriuria 5

Imaging Guidance

• Ultrasound guidance is the primary modality, showing localization of renal cavities and kidney depth 6
• Advantages include use during pregnancy, in patients with contrast allergy, or reduced renal function 6
• Combined ultrasound and fluoroscopic guidance achieves success rates exceeding 98% 6

Technical Approach

Access Site Selection

• Puncture below the 11th rib (preferably below 12th rib when feasible) to minimize pleural complications 5
• Infracostal access reduces pleural complication risk to approximately 1% 7
• Target a posterior calyx (typically inferior calyx) using Broedel's avascular plane where posterior and anterior arterial systems meet 6
• Use 20-30 degree posterolateral oblique approach for single-wall calyceal puncture 5

Procedural Technique

• Seldinger technique is most commonly employed using an 18G needle for direct puncture under ultrasound guidance 6
• Achieve adequate visualization of calices before puncture 5
• Perform exchange transfusion for opacification rather than overdistention, which increases sepsis and retroperitoneal contamination risk 5
• Dilate tract with balloon dilation system for large-bore access 5
• Use only self-retaining drainage catheters to minimize inadvertent dislodgment 5
• Place "safety wire" for all complex manipulations to maintain access 5

Catheter Selection

• Polyurethane catheters are most ductile and commonly used 6
• May be external PCN or internal/external nephroureteral catheter (PCNU) for drainage through ureter and bladder 2
• Catheters should be exchanged every 3 months to prevent encrustation 3

Safety Precautions

Critical "Do's"

• Always confirm intracollecting system location by injecting contrast via catheter placed over wire 5
• Avoid unnecessary complicated or prolonged procedures in infected, obstructed systems 5
• Use normal saline irrigation to prevent electrolyte abnormalities 7

Critical "Don'ts"

• Never puncture above the 11th rib unless all other approaches exhausted - pleural complications should not exceed 15% 7, 5
• Never lose access once obstructed kidney is punctured 5
• Avoid overdistention of collecting system during opacification 5

Complications and Management

Overall Complication Rates

• Technical success approaches 95-100% with proper imaging guidance 3
• Major and minor complications occur in approximately 10% of cases, with major complications in 4-5% 3, 4
• Mortality rate is approximately 0.04% 5

Specific Complications

Vascular Injury and Hemorrhage:

• Mild hematuria is common and should gradually resolve 3
• Excessive bleeding usually controlled with tract tamponade using balloon catheter or appropriate-sized nephrostomy tube 5
• Almost all renal artery injuries treatable with selective embolization, preserving functioning parenchyma 5

Pleural Complications:

• Pneumothorax and pleural effusions from transthoracic entry should be treated only if large or symptomatic 5

Bowel Perforation:

• Transcolonic nephrostomy can generally be treated nonsurgically 5
• Ensure adequate urinary drainage via ureteral stent and bladder catheter before removing transcolonic catheter 5
• Withdraw catheter into colon for percutaneous colostomy drainage, allow tract to mature several days 5
• Administer appropriate antibiotics until tract heals completely 5

Infection:

• Monitor for fever, increased WBC, or purulent drainage 3
• May progress to sepsis if untreated, requiring urgent intervention 3

Catheter Obstruction:

• Presents with decreased/absent urine output, flank pain, or hydronephrosis on imaging 3
• Consider gentle irrigation with sterile saline or obtain urgent imaging and consult interventional radiology/urology 3

Post-Procedural Monitoring

• Monitor urine output volume, color, and consistency as most direct indicator of proper function 3
• Ultrasonography is first-line imaging to assess for hydronephrosis indicating obstruction 3
• Loopogram/nephrostogram evaluates collecting system patency 3
• CT urography is gold standard for comprehensive evaluation when detailed assessment needed 3
• Monitor serum creatinine for inadequate drainage and worsening renal function 3

Clinical Decision Algorithm by Scenario

Septic patient with obstructive uropathy: PCN is mandatory and preferred over retrograde stenting 2, 1

Pregnant patient (20+ weeks) with infected hydronephrosis: Either retrograde stenting or PCN is appropriate 2

Malignant obstruction with renal failure (eGFR <15): Retrograde stenting, PCN, or percutaneous antegrade stenting are equivalent alternatives 2

Ureteral injury post-surgery: PCN, retrograde stenting, or antegrade stenting are equivalent, with PCN providing access for definitive treatment 2

Post-cystectomy with urinary diversion and new hydronephrosis: PCN followed by delayed surgery is preferred approach 2