Residency · Residency · Interventional Radiology

Ureteral Stenting: Antegrade Approach

Overview

Antegrade ureteral stent placement is performed via a percutaneous nephrostomy access to bypass ureteral obstruction. Indicated when retrograde (cystoscopic) stenting fails or is not feasible. Provides internal urinary drainage, eliminating the need for an external nephrostomy bag. Requires existing or de novo percutaneous nephrostomy access.

Indications

Failed Retrograde Stenting

Inability to traverse the obstruction from below (tight stricture, complete obstruction). Surgically altered anatomy (ileal conduit, neobladder, ureteral reimplantation). Ureterovaginal or ureterocutaneous fistula.

Malignant Ureteral Obstruction

Extrinsic compression from pelvic malignancies (cervical, bladder, prostate, colorectal, ovarian). Retroperitoneal lymphadenopathy. Direct tumor invasion of the ureter. Post-radiation stricture.

Benign Ureteral Obstruction

Ureteral stricture (post-surgical, post-radiation, inflammatory). Retroperitoneal fibrosis (idiopathic or drug-induced). Ureteropelvic junction obstruction. Ureteral injury repair. Post-transplant ureteral complications.

Stent Types

Polymer (Plastic) Ureteral Stents

Standard double-J or pigtail design (proximal pigtail in renal pelvis, distal pigtail in bladder). Materials: polyurethane, silicone, C-flex. Sizes: 6-8 Fr diameter, various lengths (20-30 cm). Require exchange every 3-6 months (encrustation risk). Suitable for benign obstruction and short-term malignant obstruction.

Metallic Ureteral Stents

Self-expanding metallic stents for malignant ureteral obstruction. Types: Resonance (coil design), Memokath (thermo-expandable), covered metallic stents. Advantages over polymer stents in malignant obstruction: Larger lumen → longer patency. Greater resistance to extrinsic compression. Exchange intervals: 6-12 months (longer than polymer). Resonance stent: tightly wound metallic coil, no true lumen but flow between coils; 12-month patency. Disadvantages: higher cost, MRI compatibility varies, removal can be difficult.

Nephroureteral Stent (Internal/External)

Catheter traverses from skin → renal pelvis → ureter → bladder. External end allows flushing and exchange without cystoscopy. Side holes along the entire length provide drainage at multiple levels. Used when long-term access is needed for exchanges or when complete internalization is not possible. Can be capped for internal drainage with external access preserved.

<image>Comparison of double-J polymer ureteral stent, metallic Resonance coil stent, and nephroureteral internal/external stent configurations with their respective drainage mechanisms</image>

Technique

Pre-Procedural Planning

Existing nephrostomy access preferred (tract matured ≥5-7 days). If de novo access needed: standard PCN technique with emphasis on upper or interpolar calyx for straight-line access to UPJ and ureter. Review imaging for level and nature of obstruction, ureteral anatomy, and bladder configuration. Estimate ureteral length for stent sizing.

Procedural Steps

Access through existing nephrostomy tract (remove existing catheter over wire). Antegrade nephrostogram to delineate collecting system and identify obstruction. Advance hydrophilic guidewire (Glidewire) and angled catheter through UPJ and down the ureter. Navigate through or around the obstruction. Hydrophilic wire + directional catheter for tight strictures. If unable to cross: consider balloon dilation, wire escalation, or combined antegrade-retrograde (rendezvous) approach. Advance wire into the bladder (confirm by fluoroscopic visualization of coiled wire in pelvis). For double-J stent: Advance stent over wire through the nephrostomy tract. Deploy with proximal pigtail in renal pelvis and distal pigtail in bladder. Remove wire; confirm curl formation under fluoroscopy. Remove nephrostomy access sheath; may leave safety nephrostomy for 24-48 hours. For nephroureteral stent: Advance catheter over wire; position side holes along ureter. Lock pigtail in bladder; external end secured at skin.

Difficult Crossings

Balloon dilation: 4-6 mm balloon for tight benign strictures. Stiff wire exchange: after initial crossing with hydrophilic wire, exchange for Amplatz stiff wire for support. Rendezvous technique: wire advanced antegrade through obstruction, snared from below via cystoscopy, providing through-and-through access. Cutting balloon or sharp recanalization: rare, for complete obstruction.

<image>Fluoroscopic image showing antegrade placement of a double-J ureteral stent with the proximal pigtail in the renal pelvis and distal pigtail in the urinary bladder, with the nephrostomy access sheath being removed</image>

Stent Selection for Malignant Obstruction

Polymer stents for malignant obstruction have median patency of 3-4 months. Failure rate: 15-45% due to tumor ingrowth, encrustation, and extrinsic compression. Metallic stents (Resonance) have median patency of 6-12 months. Consider metallic stents when: Expected survival >3-6 months. Prior polymer stent failures. Bilateral obstruction (reduces exchange burden). Extrinsic compression from tumor (metal resists compression better).

Tandem Stenting

Two polymer stents placed side by side for wide-bore drainage. Used when single stent provides inadequate drainage. Alternative to metallic stent in some settings.

Follow-Up and Management

Monitoring

Renal function (creatinine) checked within 1 week. Imaging (KUB or CT) to confirm stent position. Monitor for stent-related symptoms (dysuria, frequency, flank pain, hematuria).

Stent Exchange Schedule

Polymer stents: every 3-4 months (malignant) or 4-6 months (benign). Metallic stents: every 6-12 months. Can be exchanged retrograde (cystoscopy) or antegrade (nephrostomy access). Late exchanges increase encrustation and difficulty of removal.

Stent Failure Signs

Rising creatinine. Recurrent hydronephrosis on imaging. Flank pain, fever (suggests obstruction or infection). Stent migration (visible on imaging).

Complications

Stent-Related

Irritative bladder symptoms (frequency, urgency, dysuria): very common (50-80%). Hematuria (usually self-limited). Stent migration (proximal or distal). Encrustation and obstruction. Stent fracture (rare, more common with long indwelling times). Ureteral erosion or perforation (rare).

Procedure-Related

Ureteral perforation during crossing attempt. False passage creation. Hemorrhage. UTI / sepsis (especially if manipulating infected system). Loss of nephrostomy access.

Clinical Pearls

Upper or interpolar calyx access provides the best angle for antegrade ureteral catheterization — lower pole access creates a sharp angle at the UPJ that makes wire advancement difficult. For malignant obstruction expected to be permanent, metallic stents reduce the exchange burden and improve quality of life. The Resonance metallic stent has no true lumen — urine flows between the metal coils; this unique design resists extrinsic compression better than conventional stents. A safety nephrostomy tube should be left for 24-48 hours after antegrade stent placement to ensure the stent drains adequately before the access is abandoned. If antegrade wire passage fails, coordinate a rendezvous approach with urology — through-and-through wire access provides maximum control. Bilateral malignant ureteral obstruction in a patient with advanced cancer requires a frank discussion about goals of care — bilateral nephrostomy tubes may significantly impact quality of life without meaningful survival benefit. Stent-related irritative symptoms are the most common patient complaint; alpha-blockers (tamsulosin) and anticholinergics can help but do not eliminate symptoms entirely. For retroperitoneal fibrosis, consider long-term ureteral stenting with periodic exchange until medical therapy (corticosteroids, tamoxifen) takes effect.

<image>KUB radiograph showing bilateral metallic ureteral stents (Resonance coil design) with proximal coils in each renal pelvis and distal coils in the bladder for bilateral malignant ureteral obstruction</image>

References

• Pavlovic K, et al. Metallic Ureteral Stents for Malignant Ureteral Obstruction: Systematic Review and Meta-Analysis. J Vasc Interv Radiol. 2019;30(5):684-693.
• Bahu R, et al. Antegrade Ureteral Stent Placement: Technique, Indications, and Outcomes. Tech Vasc Interv Radiol. 2009;12(3):193-198.
• Wah TM, et al. Ureteral Stenting: Current and Emerging Technologies. Cardiovasc Intervent Radiol. 2020;43(7):1019-1028.
• Barton DP, et al. Metallic Ureteral Stents: A Review. Semin Intervent Radiol. 2015;32(1):70-77.
• Ganatra AM, Loughlin KR. The Management of Malignant Ureteral Obstruction Treated with Ureteral Stents. J Urol. 2005;174(6):2125-2128.

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