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Percutaneous Nephroureteral Catheter (PCNU)

A PCNU connects the renal collecting system to the bladder or urinary diversion through the ureter, while retaining a catheter segment and hub outside the flank. The external port can be connected to a bag or capped for internal drainage. Capping may remove the flank drainage bag in selected patients, but a conduit still empties into an ostomy appliance and the flank catheter remains in place.[1][2]

Distinguish the Devices​

DeviceCourse and accessMeaning of capping
PCNFlank to renal collecting system; does not itself bridge the ureterA planned trial may assess drainage through the native ureter or a separate internal stent.
PCNUFlank to collecting system and through the ureter to bladder/conduitUrine can drain internally through the catheter; the external hub remains.
Double-J stentFully internal ureteral drainageNo external drainage hub to cap; removal method depends on the device.
Retrograde transileal catheterFrom a conduit stoma retrograde to the kidneyExternal access/drainage is at the stoma, not the flank.

Catheter length, side-hole locations and retention loops differ by product. In a ureteral leak, side holes must not direct urine into the injured segment or extraluminal space.[1][2]

Advantages over a standard PCN.

  • Internal drainage when capped. A patient with a native bladder may void; with an ileal conduit, urine continues into the ostomy appliance. A capping trial is possible when the receiving bladder or conduit drains adequately.[1]
  • A second route. If the internal pathway obstructs (tumor progression, edema), the external limb can be reopened.
  • Ureteral splinting. The indwelling segment supports the ureter across a stricture, anastomosis or injury.
  • Access for later steps. The existing tract and wire route can be used for exchange or conversion to a fully internal stent.

Disadvantages.

  • External hub and skin care. The external segment can burden skin care and activity. A fully internal double-J stent avoids that segment when internal drainage is appropriate, but loses ready percutaneous access.[2][11] The reported self-care difference (RR 3.07) comes from PCN-versus-double-J studies.[2][11]
  • Bladder symptoms. A distal tip in the bladder produces stent-type irritative symptoms.[12]
  • Dislodgement and blockage. In a mixed series of 1,036 PCN, stent-placement and exchange procedures, displacement occurred after 3.57%, occlusion after 1.73%, hematuria after 1.16%, UTI after 0.87% and skin inflammation after 5.3%. Three major events (0.29%) were also reported: two deaths within 30 days attributed to procedural aggravation and one retroperitoneal bleed requiring surgery.[10]

When PCNU Is Useful​

Consider PCNU when the ureter can be crossed and ongoing external access is valuable: obstruction, selected leaks or fistulas, transplant ureteral complications, planned antegrade interventions, or a trial before conversion to an internal stent.[1][2] Ureteral leaks and fistulas are drained while the ureter is splinted, and the device can serve as a bridge to a double-J stent or, in an ileal conduit, to a retrograde transileal catheter.[1][2]

Evaluate the receiving bladder or conduit. A poorly emptying or high-pressure bladder may compromise internal drainage and requires its own management. CIRSE lists neurogenic or spastic bladders among contraindications to ureteric stenting and notes that stents require low bladder pressure for function; assess the patient’s bladder pressure and drainage before considering an internal stent.[1]

For an infected obstructed system, prompt decompression is the priority. An initial PCN with later crossing and internalization may be appropriate when sepsis, bleeding, severe obstruction or tortuosity makes prolonged manipulation undesirable. In sepsis from an obstructing stone, the EAU strongly recommends urgent percutaneous drainage or ureteral stenting.[3] For the antegrade PCNU pathway, CIRSE advises PCN decompression first when infection is active, with stent insertion after infection clears; single-session insertion is possible when infection is excluded, and no fixed 1–2-week interval is required.[1]

Placement and Exchange Principles​

Plan access with imaging and the intended future intervention in mind. Establish and confirm intraluminal wire passage across the lesion and into the receiving bladder or conduit before advancing the catheter. Hydrophilic wires and stiff support wires have different roles; neither should be forced through an uncertain path. Confirm the drainage side holes and retention portions are correctly positioned, and secure the external segment.[1][2]

PCNU placement can occur during initial access or by later conversion from a PCN, depending on infection and obstruction severity; the following describes conversion from a PCN. A standard PCN is placed first and, through the existing tract, a guidewire is advanced across the renal pelvis, the ureter and the lesion into the bladder; the tract is dilated and the PCNU is advanced over the wire until the distal pigtail forms in the bladder and the proximal end exits the flank. A stiff support wire and hydrophilic or torque-control wires help with tortuosity. Contrast confirms the distal tip in the bladder.[2]

A single-session approach has been compared with the staged route for antegrade double-J stents (not PCNU). In that retrospective series, technical success was 67/72 (93.1%) with first-hand access and 41/44 (93.2%) through a nephrostomy; median fluoroscopy times were 6.8 and 8.2 minutes, respectively, and among technically successful procedures the nephrostomy route was associated with higher adjusted odds of a recorded complication (OR 3.08, 95% CI 1.01–9.36; p = 0.047). Patients with urinary malignancy were more often stented through a nephrostomy.[4]

Capping Trials: What They Can and Cannot Show​

A trial should have an explicit purpose, monitoring plan and response to symptoms. Confirm that internal drainage is appropriate, then monitor pain, fever, pericatheter leakage, voiding or output and renal function as indicated. For an outpatient capping trial, provide a drainage bag and 24-hour contact information. Instruct the patient to uncap and reconnect to gravity drainage for fever, flank pain, new leakage or unexpectedly low urine output, contact the treating team, and seek urgent reassessment if symptoms persist.[1][2]

Capping is not proof that the ureteral obstruction has resolved

A capped PCNU still bypasses the ureteral lesion. Tolerance may support conversion to an internal stent. Removal requires a separate assessment of the underlying obstruction or leak. The capped port is also not an automatic pressure-release valve; it must be deliberately reopened when external drainage is needed.[1][2]

A PCN may also be capped when native or separately stented internal drainage is being assessed. Capping duration and testing depend on the clinical situation; 24–48 hours is not a universal removal rule.[1][2]

Maintenance and Problems​

Arrange image-guided exchange according to the device and local service, shortening the interval for blockage, encrustation or infection. Record the planned exchange and management plan in a hospital stent register.[1] The historical PCNU technique review describes starting at 6–8 weeks, with extension toward 12 weeks in patients without encrustation.[2] In a claims analysis of 19,689 nephrostomy exchanges (PCN), 41% occurred within 29 days, 67% within 59 days and 81% within 89 days.[9]

Leakage, falling output, flank pain or rising creatinine can indicate blockage, migration or malposition. Fever or systemic illness requires infection assessment and attention to drainage. Persistent or substantial bleeding needs investigation. New or intermittent gross hematuria in a patient with chronic nephroureteral catheterization and prior pelvic surgery or radiation should raise concern for ureteroarterial fistula before tube exchange or removal.[13][14] External securement and patient education remain important even while capped.[1][5]

Bacteriuria alone is not synonymous with UTI. Follow the infection treatment and procedural prophylaxis companions; pregnancy and mucosa-traumatizing endourologic procedures require specific assessment.[6]

Selected Scenarios and Evidence Limits​

Ileal conduit: a retrograde transileal catheter can provide accessible drainage into the ostomy appliance and avoid a flank tube. Internal Double-J drainage is also used. Access anatomy, mucus, patency, symptoms and maintenance burden guide choice; neither route is universally superior.[2] In a retrospective comparison of 30 patients with chronic retrograde transileal stents and 71 with PCN, renal function change did not differ. Retrograde stents needed fewer nonroutine interventions (5.9% vs 20.1%) but shorter routine exchange intervals (median 8.5 vs 12.9 weeks at 3 years, because of encrustation), and had more moderate to severe adverse events (30% vs 4.2%), mostly dislodgements that needed a new PCN.[8]

Refractory gross hematuria. In a six-patient retrospective salvage series, hematocrit remained stable, no further transfusions were needed over 30 days, and no PCNU was obstructed by clot; two patients were readmitted after tube dislodgement.[7] The authors inferred bilateral drainage clinically, but obtained no postprocedure imaging.[7] The authors intended the approach for venous bleeding, did not expect it to control arterial hemorrhage, and noted that trigonal tumor or obstructed ureteral orifices may preclude placement.[7]

Malignant obstruction. Assess drainage feasibility, prognosis, treatment goals and patient preference. CIRSE notes that high-volume pelvic malignancy can predict internal-stent failure and an irritable bladder can predict debilitating symptoms; it describes a PCNU trial in selected patients because conversion to PCN is straightforward if bladder irritation is intolerable.[1]

PCN, PCNU and Double-J Stent Compared​

FeaturePCNPCNUDouble-J stent
Drainage routeExternal onlyInternal and externalInternal only
Capping trialPossible only with a separate internal stent or native drainageYesNot applicable
External bagWhen uncapped; not during a planned capping trial.[1]Only when uncappedNo
Ureteral splintingNoYesYes
Exchange accessPercutaneousPercutaneousCystoscopic or device-specific
Main burdenExternal tube and dislodgementExternal hub, skin care and bladder symptomsStent symptoms

See also Metal & Long-Term Stents and Renal Anatomy.

References​

1. Ryan AG, Irvine I, Bardgett H, et al. CIRSE Standards of Practice on Nephrostomy and Ureteric Stent Placement and Exchange. Cardiovasc Intervent Radiol. 2026;49:464–479. doi:10.1007/s00270-025-04328-9

2. Makramalla A, Zuckerman DA. Nephroureteral Stents: Principles and Techniques. Semin Intervent Radiol. 2011;28:367–379. doi:10.1055/s-0031-1296079

3. European Association of Urology. EAU Guidelines on Urolithiasis, 2026. Sections on sepsis, ureteroscopy, stenting and pregnancy.

4. Arslan M, Aslan HS, Alver KH, Demirci M. Comparison of Percutaneous Antegrade Double-J Ureteral Stent Placement: First-Hand vs. Nephrostomy Route Approaches. British Journal of Radiology. 2024;97(1162):1683-1689. doi:10.1093/bjr/tqae143

5. Yoo MJ, Bridwell RE, Inman BL, Henderson JD, Long B. Approach to Nephrostomy Tubes in the Emergency Department. The American Journal of Emergency Medicine. 2021;50:592-596. doi:10.1016/j.ajem.2021.09.034

6. Nicolle LE, Gupta K, Bradley SF, et al. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by IDSA. Clin Infect Dis. 2019;68:e83–e110. doi:10.1093/cid/ciy1121

7. Spradling K, Elliott CS, Vo H, Reese J. Percutaneous Nephroureteral Tube: A Useful Tool for Management of Intractable Hematuria. Urology. 2019;126:232-235. doi:10.1016/j.urology.2019.01.003

8. Dawson C, Brar L, Rey C, Huynh MJ, Cool DW. Outcomes of Retrograde Transileal Ureteric Stents for Chronic Urinary Drainage: Comparison With Chronic Nephrostomy Tube Drainage. Journal of Vascular and Interventional Radiology. 2026;37(7):108785. doi:10.1016/j.jvir.2026.108785

9. Moon JT, Nguyen J, Ricci J, et al. Analysis of Percutaneous Nephrostomy Exchange Intervals: Insights From a Retrospective Merative MarketScan Analysis Between 2009–2021. World Journal of Urology. 2024;42(1):424. doi:10.1007/s00345-024-05132-9

10. Kaskarelis IS, Papadaki MG, Malliaraki NE, et al. Complications of Percutaneous Nephrostomy, Percutaneous Insertion of Ureteral Endoprosthesis, and Replacement Procedures. Cardiovascular and Interventional Radiology. 2001;24(4):224-228. doi:10.1007/s00270-001-0004-z

11. Zhang KP, Zhang Y, Chao M. Which Is the Best Way for Patients With Ureteral Obstruction? Percutaneous Nephrostomy Versus Double J Stenting. Medicine. 2022;101(45):e31194. doi:10.1097/MD.0000000000031194

12. Lange D, Bidnur S, Hoag N, Chew BH. Ureteral Stent-Associated Complications: Where We Are and Where We Are Going. Nature Reviews Urology. 2015;12(1):17-25. doi:10.1038/nrurol.2014.340

13. Ebata Y, et al. "A systematic review of management of ureteroarterial fistula." J Vasc Surg. 2022;76(5):1417-1423.e5. doi:10.1016/j.jvs.2022.05.015

14. Campbell JA, et al. "Massive hemorrhage and cardiac arrest due to ureteroarterial fistula following nephroureteral stent removal: A case report." Urology Case Reports. 2026;66:103426. doi:10.1016/j.eucr.2026.103426