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Indications / Contraindications
Indications
- Routine scheduled exchange: Standard nephrostomy catheters exchange every 3 months. Pigtail/Cope loop catheters prone to encrustation and occlusion.
- Catheter malfunction: Occlusion, poor drainage, or leaking around catheter
- Catheter dislodgement (partial): Wire still accessible through tract — exchange, not new placement
- Catheter degradation (softening, cracking of external hub)
- Suspected/confirmed catheter-associated infection with drain dysfunction
- Upsizing catheter for improved drainage or tract dilation
Not an Exchange
Complete dislodgement of catheter with no wire/catheter access = new PCN placement required. Treat immature tract (<4-6 weeks) dislodgement as urgent — new PCN, not exchange.
Contraindications
- Complete dislodgement — no catheter access remaining through tract
- Uncooperative patient (local only; if patient can't hold still, consider moderate sedation)
- Uncorrectable coagulopathy (relative — Cat 1 procedure, very low bleeding risk)
SIR Bleeding Risk
Category 1. Mature tract — exchange is low risk. No routine coagulation testing required.
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Pre-Procedure Checklist
Confirm catheter can be accessed. Is any portion still in tract? If completely dislodged → new PCN placement required, not exchange.
Check existing catheter date and last exchange. Note catheter size and type. Have same size (or 2 Fr larger if upsizing) ready before starting.
Antibiotics: NOT routine. Consider ceftriaxone 1g IV only if: active UTI on urine culture, immunocompromised, diabetic, or infected urine on prior culture.
Local anesthesia only. Mature tract is fibrosed — 1% lidocaine at skin entry site only. Warn patient they may feel pressure but not sharp pain.
Review any recent imaging. New stone burden, significant collecting system change — may affect whether exchange is appropriate or new access needed.
Patient positioning: prone. Standard PCN access position.
New catheter confirmed in room before removing old catheter. Have correct size ready.
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Relevant Anatomy
The Mature Nephrostomy Tract
- Mature tract: Fibrosed channel from skin → subcutaneous tissue → retroperitoneal fat → renal capsule → renal parenchyma → target calyx. Takes 4-6 weeks to mature.
- Tract window: After catheter removal, a mature tract stays open for approximately 15-30 minutes before beginning to close. Do NOT remove old catheter until new one is ready and wire is confirmed in collecting system.
- Immature tract (<4-6 weeks): May close rapidly — treat dislodgement as urgent. New access often needed.
- The tract is avascular once mature — exchange is low risk for bleeding. Main risk is wire loss.
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Technique
Default RadCall approach · share your own below
Supplies
Fluoroscopy (C-arm)
Dilute contrast + syringe
0.035" Amplatz super-stiff guidewire
New nephrostomy catheter (same size or 2 Fr larger)
1% lidocaine (minimal)
#11 blade (only if upsizing significantly)
Suture material (0-silk)
Sterile drape + ChloraPrep
Steps
1
Prepare field
Sterile prep and drape around catheter exit site. Note current external length marking on catheter — this is your reference depth for the new catheter.
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Nephrostogram FIRST
Inject 10-15 mL dilute contrast through existing catheter. Document catheter position, drainage pattern, collecting system appearance. Confirm catheter is actually where you think it is. Check for any new stones or collecting system changes.
3
Unlock pigtail locking string
Do not skip this step. Most nephrostomy catheters have a locking string that forms the pigtail curl. If you don't unlock it, the wire cannot advance distally and will kink at the loop. Unlock before wire passage.
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Advance guidewire
Advance 0.035" Amplatz super-stiff wire through existing catheter into collecting system. Advance well into renal pelvis — ideally into proximal ureter for maximum purchase. Confirm wire position under fluoroscopy.
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Hold wire, remove old catheter
Pinch wire at skin entry with one hand. Do NOT let go. With other hand, withdraw old catheter over the wire. Watch fluoroscopy to confirm wire tip stays coiled in renal pelvis/ureter. This is the highest-risk moment of the procedure.
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Confirm wire position
Brief fluoroscopic check: wire tip still coiled in renal pelvis or ureter. Not displaced to retroperitoneum. If wire position uncertain — inject contrast alongside wire if any catheter remnant present, or place a new catheter immediately.
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Advance new catheter
Advance new nephrostomy catheter over wire to same depth as old catheter (match external length marking). Form pigtail/release locking mechanism. Withdraw wire.
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Post-exchange nephrostogram
Inject contrast through new catheter. Confirm: pigtail coiled in renal pelvis, free drainage, no extravasation. This confirms correct positioning before securing.
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Secure new catheter
Suture at skin. Connect to drainage bag. Document new catheter size, date, external catheter length, and next exchange date (3 months). Provide patient/nursing education.
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Troubleshooting
Problem
Wire won't advance through existing catheter
Likely cause: Catheter kinked, coated with encrustation, or pigtail lock not released.
Next step: First check that pigtail locking string is released. Try rotating catheter while advancing wire. Inject contrast first — may show kink or obstruction. If wire truly won't pass: place new wire alongside existing catheter under fluoroscopy using any visible portion of the tract.
Problem
Lost wire access
Likely cause: Wire withdrawn accidentally during catheter removal.
Next step: STOP. Place sterile gauze over site. If tract is mature (>4 weeks) and fresh, can attempt blind wire re-insertion or dilating sounds to re-establish tract access. If tract immature or access cannot be re-established → new PCN placement required. This is the most feared complication of exchange.
Problem
New catheter won't advance over wire
Likely cause: Tract narrowed, skin adhesion, or catheter too large without dilation.
Next step: Dilate tract with 1-2 dilators. Or use a peel-away sheath to maintain tract access. Can safely upsize 2-4 Fr without formal dilation in mature tracts — larger upsizing requires dedicated tract dilation procedure.
Problem
Post-exchange hematuria — frank red blood
Likely cause: Usually tract oozing into collecting system; rarely vascular injury.
Next step: Confirm catheter is well-positioned in renal pelvis on fluoroscopy. Pink/red urine is expected — should clear. If persistent bright red blood: CT to evaluate for vascular injury (pseudoaneurysm, AV fistula).
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Complications
Immediate
- Wire loss — most feared; requires new PCN placement or tract salvage attempt. Prevention: never let go of wire.
- Post-exchange hematuria — common, usually self-limited. Pink urine expected ×24-48h.
- Catheter malposition — pigtail not in renal pelvis; confirmed/corrected with post-exchange nephrostogram
- Urinoma — from extravasation during exchange if catheter placed outside collecting system
Delayed
- Tract infection — skin/peristomal; local wound care ± antibiotics
- Catheter occlusion — requires earlier than scheduled exchange
- Subcapsular hematoma — rare after exchange of mature tract
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Post-Procedure Care
Monitoring
- Output monitoring for 2-4h post-exchange
- Urine color: pink → clear expected over 24-48h. Frank bright red blood: reassess on fluoroscopy.
- No activity restrictions specific to exchange (patient already has established drain)
Documentation
- Catheter size, date of exchange, and next scheduled exchange date (3 months)
- External catheter length at skin entry
- Nephrostogram findings (pre- and post-exchange)
- Suture placement confirmed
- Patient/nursing education provided
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Critical Pearls
✦
NEVER let go of the wire. Wire loss = new PCN placement. Pinch wire firmly at skin entry before withdrawing the old catheter. Watch fluoroscopy the entire time. This is the most important technical point of the entire procedure.
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Unlock the pigtail locking string BEFORE advancing wire. Easily forgotten in routine cases. If you don't unlock it, the wire cannot advance past the coil and will buckle. Always unlock first.
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Stiff wire (Amplatz) is essential. A floppy wire buckles in the renal pelvis and fails to provide support during catheter advancement. Amplatz super-stiff is the default for exchange.
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Take a nephrostogram BEFORE the exchange. Confirms catheter position, provides a roadmap, and occasionally reveals the catheter is malpositioned or that the collecting system has changed significantly. Never skip it.
✦
If the tract is immature (<4-6 weeks) and catheter is dislodged — treat as urgent, not routine exchange. An immature tract closes fast. This is a time-sensitive procedure requiring new PCN access if the wire cannot be re-established immediately.
✦
Upsizing safely: Can go 2-4 Fr larger without dedicated dilation in a mature tract. Need to go larger (e.g., 8 Fr → 14 Fr or more)? Schedule a formal tract dilation procedure, not just an exchange.
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Exchange Schedule & Documentation
Standard Exchange Intervals
| Catheter Type | Exchange Interval |
|---|---|
| 8-10 Fr pigtail (Cope loop) | Every 3 months |
| 14 Fr pigtail | Every 3-4 months |
| Silicone catheters | Every 4-6 months |
| Any catheter | Earlier if: occlusion, infection, or malfunction |
Documentation Checklist
- Date of exchange
- Previous catheter size and type
- New catheter size and type
- Pre-exchange nephrostogram findings
- Post-exchange nephrostogram findings
- External catheter length at skin
- Suture placement confirmed
- Next exchange date
- Patient/nursing education provided
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References & Resources
Primary sources · Key data · Related procedures
Key Guidelines
- SIR practice standards for tube exchanges
Primary References
- Ramchandani P, Cardella JF, Grassi CJ, et al. Quality improvement guidelines for percutaneous nephrostomy. J Vasc Interv Radiol. 2003;14(9 Pt 2):S277–S281.
- Dyer RB, Regan JD, Kavanagh PV, et al. Percutaneous nephrostomy with extensions of the technique: step by step. Radiographics. 2002;22(3):503–525.
- Smith AD, Lange PH, Miller RP, Reinke DB. Controlled comparison of percutaneous nephrostomy and ureteral stent in obstructive uropathy. J Urol. 1979;122(4):425–428.