Ureteral Anatomy — Clinical Relevance for Dilatation
The ureter is a muscular tube approximately 25–30 cm in length, spanning from the renal pelvis to the urinary bladder. Its wall consists of three layers — urothelium, lamina propria, and smooth muscle — affording both distensibility and structural resilience under controlled radial force. Understanding the anatomical narrowings and their clinical behaviour underpins safe balloon dilatation technique.
Three physiological narrowings are of particular procedural importance: the ureteropelvic junction (UPJ), the crossing of the iliac vessels (mid-ureter), and the ureterovesical junction (UVJ). Of these, the UVJ is the narrowest segment and most frequently the site of both calculus impaction and pathological stricture formation.
UPJ
Ureteropelvic Junction
Common site of congenital obstruction; approach with careful pre-dilatation assessment
Mid
Iliac Crossing
Posterior crossing adds tortuosity; kink-resistant shaft design critical for balloon advancement
UVJ
Ureterovesical Junction
Most frequent stricture site; high-pressure balloon most often required for adequate dilatation
Why High Pressure Matters
Ureteral strictures — particularly post-inflammatory, post-surgical, or radiation-induced — develop dense fibrotic walls with significantly increased tensile strength. Standard low-pressure balloons (≤ 8 ATM) are frequently insufficient to achieve sustained radial expansion in these tissues. High-pressure rated balloons (up to 20 ATM) are designed to deliver complete, uniform dilation without balloon waisting, eliminating the risk of partial dilatation that predisposes to early recurrence.
Ureteral Stricture Classification
Classifying strictures prior to intervention guides both balloon size selection and intraoperative pressure targets. Aetiology, length, and degree of fibrosis all independently affect procedural planning.
| Aetiology | Typical Location | Fibrosis Density | Pressure Requirement |
|---|---|---|---|
| Post-ureteroscopic instrumentation | UVJ / distal ureter | Mild – Moderate | 10–15 ATM |
| Post-surgical (ureteral reimplantation) | UVJ / anastomosis | Moderate – Dense | 15–20 ATM |
| Radiation-induced fibrosis | Variable (pelvic field) | Dense – Very dense | Up to 20 ATM |
| Congenital UPJ obstruction | Ureteropelvic junction | Mild (membranous) | 8–12 ATM |
| Ischemic (transplant ureter) | UVJ / anastomosis | Dense | 15–20 ATM |
| Calculus-induced (impacted stone) | UVJ or mid-ureter | Mild – Moderate | 10–18 ATM |
Staging Recommendation
For strictures of unknown aetiology, or those arising in a field with prior radiation or ischaemia, pre-operative cross-sectional imaging (CT urogram or MRI urogram) and urine cytology are recommended before dilatation. Malignant ureteral obstruction requires tissue sampling before any dilatation procedure is undertaken.
Indications & Contraindications
Indications
- • Benign ureteral stricture with obstructive uropathy
- • UPJ obstruction (primary or recurrent)
- • Pre-ureteroscopy dilatation to facilitate scope passage
- • Access dilatation for ureteral access sheath placement
- • Post-surgical anastomotic stricture (renal transplant)
- • Ureterovesical junction stenosis following stone impaction
- • Dilatation prior to ureteroscopic lithotripsy in narrow ureters
Contraindications
- • Suspected or confirmed malignant ureteral obstruction (until excluded)
- • Active untreated urinary tract infection
- • Ureteral perforation or recent iatrogenic injury
- • Uncorrected coagulopathy (relative)
- • Inability to advance guidewire across the stricture
- • Complete ureteral obstruction not amenable to guidewire passage
EAU Guideline Position (2024)
The EAU guidelines on upper urinary tract urothelial carcinoma and urolithiasis recommend that balloon dilatation of the ureter is a first-line endoscopic option for short (< 2 cm) benign ureteral strictures, particularly when recurrence risk is low. For longer or denser strictures, endoureterotomy or open/laparoscopic reconstruction may offer superior long-term patency and should be considered as early as the first recurrence after dilatation.
Balloon Selection Principles
Correct balloon selection is critical to procedural success. Key parameters include balloon diameter, balloon length, shaft length, guidewire compatibility, and rated burst pressure.
1. Balloon Diameter — Match to Target Lumen
Select the balloon diameter to match the target post-dilatation lumen. For pre-ureteroscopy access dilatation, 12–15 Ch is typically appropriate to accommodate the scope. For stricture treatment aiming at long-term patency, diameter should match normal adjacent ureteral calibre — generally 15–18 Ch in the proximal ureter, 12–15 Ch at the UVJ. Over-dilation risks mucosal tearing and accelerated re-stenosis.
2. Balloon Length — Centre on the Stricture
Balloon length must exceed stricture length to ensure complete coverage. For focal strictures, a 2–4 cm balloon is appropriate. For extended or multifocal strictures, longer balloons reduce the number of inflation cycles required. The radiopaque markers at each end of the balloon — both proximal and distal — confirm correct positioning under fluoroscopy before inflation is initiated.
3. Shaft Design — Kink Resistance in Tortuous Anatomy
The ureter presents multiple curves and may be excessively tortuous in post-surgical or obese patients. A kink-resistant catheter shaft maintains axial column strength during advancement and prevents balloon mispositioning from shaft deflection. The hydrophilic coating on the shaft distal end reduces friction on insertion through tight segments and is essential in tortuous or oedematous ureters.
4. Rated Burst Pressure — Choose High-Pressure for Fibrotic Strictures
Fibrotic ureteral strictures require inflation to rated burst pressure for effective dilatation. Standard balloons rated at 8–10 ATM are insufficient for dense fibrosis. High-pressure balloons rated up to 20 ATM allow the surgeon to escalate inflation pressure until the waist (the fluoroscopic indentation at the stricture site) fully resolves — confirming complete dilatation. Waist persistence at maximum rated pressure is an indication for alternative strategies including endoureterotomy.
Special Case: Ureteroscopy Balloon Dilatation
When scope access is required for inspection or lithotripsy without first withdrawing the ureteroscope for balloon exchange, a ureteroscopy-specific balloon catheter delivered through the working channel eliminates the need for scope removal. These devices feature an ultra-low-profile shaft (fitting a 5 Fr working channel), maintaining scope-in-ureter position whilst dilating a distal stricture or tight UVJ. This approach reduces operative time and minimises repeated ureteral trauma from scope exchanges.
Step-by-Step Procedural Technique
The following technique applies to standard over-the-wire ureteral balloon dilatation under fluoroscopic guidance. Pre-operative urine culture must be negative, or an appropriate antibiotic administered if culture-positive.
Cystoscopy & Ureteral Orifice Identification
Position the patient in lithotomy. Perform cystoscopy and identify the ipsilateral ureteral orifice. Confirm orifice configuration and degree of stenosis under direct vision. For very tight or fibrosed orifices, a hydrophilic-coated guidewire facilitates entry.
Guidewire Placement & Fluoroscopic Confirmation
Advance a 0.035" or 0.038" hydrophilic guidewire through the ureteral orifice and across the stricture under fluoroscopy. Confirm wire position in the renal pelvis. If resistance is encountered at the stricture, a gentle torquing technique with a J-tip wire or angled-tip wire may facilitate passage. Never force the wire against resistance — consider ureteroscopic guidance if guidewire passage cannot be achieved fluoroscopically.
Balloon Catheter Advancement
Thread the balloon catheter over the guidewire and advance to the stricture. The hydrophilic coating on the balloon and distal shaft reduce friction during advancement through the oedematous or inflamed ureteral wall. Maintain guidewire position throughout — do not advance the catheter without wire support.
Fluoroscopic Positioning — Marker Band Alignment
Under fluoroscopy, align the proximal and distal radiopaque marker bands so that the stricture lies entirely within the balloon segment. The waist of the stricture should be visible as an indentation between the markers. Confirm both markers are visible and centred before inflation.
Controlled Inflation to Rated Pressure
Inflate the balloon with dilute contrast medium using an inflation syringe or pressure gauge. Increase pressure incrementally — pausing at 5, 10, 15 ATM to observe fluoroscopic waist resolution. Inflate to the rated burst pressure (up to 20 ATM for the Tahina™ balloon) and hold for 60–120 seconds. Complete waist resolution confirms adequate dilatation. If the waist persists at maximum rated pressure, deflate, reposition and re-inflate, or consider that this stricture may require endoureterotomy.
Deflation, Removal & Stenting
Fully deflate the balloon before withdrawal. Inspect the dilatation site ureteroscopically or by fluoroscopy with contrast. Place a ureteral stent (double-J, 4–6 Fr) over the guidewire and leave in situ for 4–6 weeks to maintain patency while the urothelium heals. Stent dwell time may be extended to 8–12 weeks for denser strictures. Remove the stent and perform a nuclear medicine diuresis renogram or CT urogram at 3 months to assess outcome.
Ureteroscopy Balloon Dilatation — Through-the-Scope Technique
The Tahina™ Ureteroscopy Balloon Dilator is purpose-designed for delivery through a 5 Fr working channel of a flexible ureteroscope. This through-the-scope approach is particularly advantageous in scenarios where the surgeon requires simultaneous dilatation and endoscopic inspection — such as confirming stone clearance in a dilated calyx, or managing a distal stricture without removing the scope.
When to use through-the-scope dilatation
- • Tight UVJ encountered during scope insertion — dilate without scope withdrawal
- • Ureter tightened during ureteroscopic lithotripsy — dilate to allow scope repositioning
- • Intraoperative post-lithotripsy access sheath placement after proximal fragment clearance
- • Infundibular or calyceal neck dilatation for lower pole stone access
Technical key points
- • Advance the 3.5 Fr shaft through the working channel under direct vision
- • Confirm radiopaque marker alignment before inflation
- • Maintain scope position — do not advance the scope during balloon inflation
- • Inflate to rated burst pressure (up to 20 ATM); hold for 60–90 seconds
- • Deflate fully before advancing or withdrawing through the working channel
- • Inspect with the scope immediately after deflation to assess dilatation result
Scope Protection During Dilatation
When inflating a balloon through the working channel, ensure the scope is not in a fully deflected position as this may restrict balloon passage and risk working channel damage. Straighten the scope tip before advancing the balloon catheter. Monitor fluoroscopically for balloon migration — if the balloon shifts proximally during inflation, immediately deflate before repositioning.
Complication Avoidance
Ureteral Avulsion — Prevention
Avulsion is the most catastrophic complication of ureteral dilatation. Risk is highest when the balloon is inflated too rapidly, when the balloon diameter significantly exceeds the target lumen, or when the balloon is inflated outside the stricture segment. Always inflate under fluoroscopic control, always confirm both marker bands are visible and centred on the stricture, and never exceed the rated burst pressure of the chosen balloon.
Ureteral Perforation
Perforation typically occurs at the point of maximum pressure, particularly if the balloon is eccentrically positioned or if the stricture is very short. If extravasation of contrast is observed during balloon inflation, immediately deflate and assess the extent of perforation. Minor perforations may be managed by leaving the guidewire in place, stenting, and observation. Major perforations require ureteral stenting, urinary diversion, and surgical review.
Stricture Recurrence — Optimising Long-Term Patency
Balloon dilatation achieves short-term patency rates of 50–85% at 12 months for benign strictures, but recurrence is the primary limitation. Key strategies to reduce recurrence include: use of high-pressure balloons to achieve complete initial dilatation (waist elimination), appropriate post-dilatation stenting duration (minimum 4 weeks), and treating any underlying cause (e.g. calculus clearance, infection control, optimising renal transplant immunosuppression).
| Complication | Incidence | Prevention |
|---|---|---|
| Post-procedural fever / UTI | 5–15% | Pre-op sterile urine; peri-procedural antibiotic prophylaxis |
| Haematuria (transient) | 50–80% | Expected; resolves within 24–48 h; ensure adequate hydration |
| Ureteral perforation | 1–3% | Fluoroscopic guidance; correct balloon sizing; incremental inflation |
| Balloon migration during inflation | 5–10% | Confirm marker placement before inflation; maintain steady guidewire position |
| Ureteral avulsion | < 0.5% | Never exceed rated burst pressure; fluoroscopy mandatory; correct balloon diameter |
| Stricture recurrence at 12 months | 15–50% | Complete waist resolution; adequate stent dwell time; treat underlying cause |
Guideline Summary — Key Recommendations
EAU Guideline Position — Ureteral Stricture Disease (2024)
- • Balloon dilatation is a first-line endoscopic option for short benign strictures (< 2 cm)
- • Success rates of 50–85% at 1 year for benign strictures; lower for radiation or ischaemic aetiology
- • For recurrent or longer strictures, open or laparoscopic ureteral reconstruction is preferred
- • Post-dilatation stenting for a minimum of 4–6 weeks is recommended
- • Malignant obstruction must be excluded before balloon dilatation is performed
AUA Best Practice Statement — Ureteroscopy & Ureteral Dilatation
- • Routine pre-ureteroscopy ureteral dilatation is not required in most adult patients
- • Dilatation is indicated when scope passage is impeded and cannot be safely forced
- • Balloon or fascial dilators are preferred over sequential metal dilators for reduced trauma
- • Fluoroscopic guidance is strongly recommended for all ureteral balloon dilatation procedures
Envaste Products for Ureteral Dilatation
The Tahina™ range is designed specifically around the demands of high-pressure ureteral dilatation — featuring hydrophilic-coated shafts, kink-resistant construction, and rated burst pressures up to 20 ATM for reliable performance in even the most fibrotic ureteral strictures.
Tahina™ Ureteral Balloon Dilator
The Tahina™ Ureteral Balloon Dilator is the standard-of-care choice for over-the-wire dilatation of ureteral strictures. Available in a wide range of diameters and lengths, the balloon achieves consistent radial expansion without waisting, even at pressures up to 20 ATM. The hydrophilic coating on the balloon and distal shaft minimises insertion trauma through tight, tortuous ureteral segments. A kink-resistant shaft maintains column strength during advancement. Dual radiopaque marker bands confirm accurate fluoroscopic positioning at the stricture site.
Tahina™ Ureteroscopy Balloon Dilator
The Tahina™ Ureteroscopy Balloon Dilator is designed for through-the-scope delivery through the 5 Fr working channel of a flexible ureteroscope. Available in 12 Ch and 15 Ch sizes, it enables intraoperative ureteral dilatation without requiring scope withdrawal or exchange — preserving the procedural workflow for combined inspection and dilatation. The low-profile 3.5 Fr shaft is hydrophilic-coated and kink-resistant for smooth delivery. Inflation up to 20 ATM ensures effective dilatation of narrow or fibrotic segments even in this compact format.
Quick Comparison — Tahina™ Balloon Range
| Product | Delivery | Max Pressure | Sizes | Hydrophilic | Guidewire |
|---|---|---|---|---|---|
| Tahina™ Ureteral | Over-the-wire | 20 ATM | Wide range | Balloon + shaft ✓ | Up to 0.038" |
| Tahina™ Ureteroscopy | Through-the-scope (5 Fr) | 20 ATM | 12 Ch / 15 Ch | Balloon + shaft ✓ | Standard wire |