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Nephroureteral Stent — Internal-External Drainage

A nephroureteral stent (NUS) — also called an internal-external stent — is a single catheter that traverses the entire collecting system from external skin to bladder, providing combined external and internal drainage through one tube.

Design​

  • Long catheter (up to 60+ cm) entering through a percutaneous nephrostomy tract, traversing the renal pelvis, ureter, and ending with a retention coil in the bladder
  • External hub and connector at the flank for drainage-bag attachment
  • Sideports along the length to allow flow into the ureter / bladder
  • Cap on the external end — when capped, urine drains internally to the bladder (like a DJ stent); when uncapped, it drains externally to a bag (like a nephrostomy tube)

Indications​

The NUS is chosen when both modes of drainage are anticipated or when a transition from external to internal is planned:

  • Ureteral stricture with failed retrograde stenting — antegrade NUS delivers both decompression and anatomic tract maintenance
  • Pre-operative decompression before complex ureteral reconstruction
  • Traversing a distal obstruction when a retrograde approach is impossible
  • Ureteral injury management — maintains the ureteral tract during healing
  • Transition to internal drainage — external mode during acute illness, then capped to internal mode as the patient improves

Advantages over Separate PCN + DJ​

  • Single catheter, single tract
  • Preserves ureteral luminal patency across a strictured or injured segment
  • Simple conversion between external and internal drainage
  • Fewer patient interventions

Disadvantages​

  • Larger tract profile than a ureteral stent
  • External component still requires dressing and skin care when uncapped
  • Generally more expensive than a simple PCN or DJ

Placement​

  • Antegrade via interventional radiology after nephrostomy access is established
  • Guidewire navigated through the ureter into the bladder
  • NUS advanced over the wire; distal coil deployed in bladder

Exchange​

  • Similar to nephrostomy — exchange every 8–12 weeks typical

See also: Double-J Stent, Nephrostomy Tube.