How to assess if a nephrostomy (percutaneous nephrostomy tube) tube is functioning properly?

Assessment of Nephrostomy Tube Function

To properly assess if a nephrostomy tube is functioning, monitor for adequate urine output, check for tube patency, and evaluate for complications such as obstruction, displacement, or infection. 1

Primary Assessment Methods

• Urine Output Monitoring: Adequate and consistent drainage is the most direct indicator of proper nephrostomy tube function. Monitor the volume, color, and consistency of urine output 1, 2
• Tube Patency Check: Ensure there is no kinking, obstruction, or displacement of the tube. Obstruction can manifest with signs of hydronephrosis or flank pain 2
• Physical Examination of Tube Site: Look for proper positioning at the skin exit site, absence of leakage around the tube, and signs of infection (redness, swelling, discharge) 2

Diagnostic Evaluations

Imaging Studies

• Ultrasonography: First-line imaging to assess for hydronephrosis, which may indicate tube obstruction or malfunction 1
• Loopogram/Nephrostogram: Contrast study through the nephrostomy tube to evaluate collecting system patency and detect any obstruction or leakage 1
• CT Urography: Gold standard for comprehensive evaluation of the urinary tract when more detailed assessment is needed 1

Laboratory Tests

• Urine Analysis: Check for signs of infection (pyuria, bacteriuria) or bleeding (hematuria) 2
• Serum Creatinine: Rising levels may indicate inadequate drainage and worsening renal function 1
• Drain Fluid Analysis: In cases where leakage is suspected, drain fluid creatinine-to-serum creatinine ratio can help identify urinary leaks 1

Common Complications to Monitor

• Obstruction: May present with decreased or absent urine output, flank pain, or hydronephrosis on imaging 1, 2
• Displacement/Dislodgement: One of the most common complications (up to 10% in some series), requiring prompt repositioning 3, 4
• Infection: Manifests as fever, increased white blood cell count, or purulent drainage; may progress to sepsis if untreated 1, 2
• Bleeding: Mild hematuria is common (present in ~50% of patients after PCN), but persistent or severe bleeding requires further evaluation 1, 4

Troubleshooting Algorithm

1. For decreased/absent drainage:

   • Check for kinks in the tubing 2
   • Ensure collection bag is positioned below kidney level 2
   • Consider gentle irrigation with 3-5 mL sterile saline if obstruction is suspected (caution: only perform if trained) 2
   • If unsuccessful, obtain urgent imaging and consult interventional radiology or urology 1

2. For tube displacement:

   • Do not attempt to reposition a completely dislodged tube 2
   • Secure any partially dislodged tube in place and obtain urgent imaging 3, 2
   • Apply sterile dressing to the site and seek immediate specialist consultation 2

3. For signs of infection:

   • Obtain urine culture and blood cultures if systemically unwell 2
   • Initiate appropriate antibiotic therapy 1
   • Ensure adequate drainage; consider tube exchange if infected 2

Preventive Measures

• Proper Tube Fixation: Use secure anchoring techniques to prevent dislodgement; consider reinforcement methods for high-risk patients 3
• Regular Site Care: Clean the exit site and change dressings according to institutional protocols 2
• Patient Education: Instruct on proper tube care, signs of complications, and when to seek medical attention 2

Important Caveats

• Mild hematuria is common after nephrostomy tube placement (up to 50% of cases) but should gradually resolve 1
• Asymptomatic bacteriuria is common in patients with nephrostomy tubes and generally should not be treated unless symptomatic 2
• Technical success rates for PCN placement approach 95-100% when performed with proper imaging guidance, but complications still occur in approximately 10% of cases 1, 5
• One-step PCN techniques have shown higher success rates and fewer complications compared to traditional fascial dilator systems, especially in challenging cases 6