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Ureteroscope (URS): Complete Classification & Urological Guide

Source: Campbell-Walsh-Wein Urology (9th/11th Ed.), Hinman's Atlas of Urologic Surgery, Smith & Tanagho's General Urology

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1. What Is a Ureteroscope?

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2. Classification of Ureteroscopes

A. By Shaft Flexibility

1. Rigid Ureteroscopes (Historical)

• Early large-diameter rod-lens instruments (e.g., 11.5 Fr ureteral resectoscopes)
• Still available in some centers for specific procedures (large distal ureteral tumor resection, endopyelotomy)
• Required ureteral pre-dilation almost universally
• Largely replaced by semirigid and flexible types
• Higher risk of ureteral injury due to inflexibility

2. Semirigid Ureteroscopes

• Incorporate fiber-optic bundles (coherently arranged glass fibers with a cladding layer to improve internal reflection and image transmission)
• Light bundles: randomly arranged fibers transmit illumination; image bundles: coherently arranged fibers coalesce for image transmission
• Two light bundles allow centrally placed working channel and better field illumination
• Tip diameters typically 7 Fr or less; working channels >3 Fr

• Single large channel vs. two separate smaller channels (preferred)
• Dual channels allow irrigation through one while instrument occupies the other
• Dual channels permit lithotripsy of a basket-trapped stone without entanglement

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3. Flexible Ureteroscopes

1. Optical system - flexible fiber-optic image and light bundles (non-digital) or chip-on-tip CCD (digital)
2. Active deflection mechanism - control wires running the scope length controlled by a thumb lever
3. Working channel - typically 3.6 Fr

• Primary deflection (up/down): typically 170-270°
• Secondary deflection (exaggerated primary): allows full calyceal access
• Greater deflection reduces working channel diameter and limits instrument passage

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B. By Size (French Gauge)

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C. By Working Channels

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3. Indications for Ureteroscopy

Primary Indications (Campbell-Walsh):

• Ureteral stones of any size (AUA/EAU: URS or SWL for ureteral calculi)
• URS preferred over SWL for stones >10 mm (higher stone-free rate)
• Intrarenal stones <20 mm (non-lower pole): either SWL or URS
• Stones >20 mm: PCNL preferred; URS reserved for poor PCNL candidates
• Lower pole stones <10 mm: SWL or URS
• Stones resistant to SWL (calcium oxalate monohydrate, brushite, cystine): URS preferred
• Pregnant patients with symptomatic ureteral stones

• EAU guidelines: diagnostic ureteroscopy when imaging is equivocal or conservative management is considered
• Ureteroscopic biopsy for tissue diagnosis
• Surveillance after nephroureterectomy

• Diagnostic evaluation
• Endoscopic incision (ureterotomy) via laser or cutting balloon

• Evaluate upper tract source of hematuria
• Evaluate filling defects on pyelography

• Endopyelotomy (UPJ obstruction)
• Calyceal diverticular neck dilation
• Foreign body retrieval from ureter/renal pelvis
• Surveillance of conservatively managed UTUC
• Evaluation of ureteral injuries or fistulae

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4. Essential Equipment for Ureteroscopy

Guidewires

• 0.038" angled hydrophilic - maneuvering around stones, tight strictures
• 0.038" straight Teflon-coated - safety wire (maintains access)
• 0.038" Nitinol core, polyurethane coated - flexible and torque-responsive
• 0.038" Extra-stiff - access sheath and stent placement

Ureteral Access Sheaths (UAS)

• Placed over super-stiff guidewire before flexible URS
• Sizes: 11/13 Fr to 16/18 Fr dilator/sheath; lengths 28, 36, 46 cm
• Enables repeated scope passes, lowers intrarenal pressure, improves irrigation
• Manufacturers: Boston Scientific (Navigator), Cook, Applied Medical, Bard

Lithotripsy Devices

Stone-Retrieval Devices

• Helical (Segura) basket - general retrieval
• Tipless basket - pass over/around stone without displacing it
• Nitinol flat-wire basket - for biopsy and larger fragments
• Three-prong grasping forceps - fragmented stone retrieval
• 3-Fr cup biopsy forceps - tissue sampling

Antiretropulsion Devices

• Stone Cone (Boston Scientific)
• N Trap (Cook Urological)
• Accordion (PercSys)
• BackStop gel (Boston Scientific)
• Reverse Trendelenburg positioning

Ureteral Dilation Devices

• Hydrophilic dilating catheters (6-Fr tip to 12-Fr shaft)
• High-pressure ureteral balloon dilators (12-30 Fr, 8-20 atm)
• "Zero-tip" balloon dilators - safe adjacent to impacted stones
• Passive dilation: pre-procedure ureteral stenting 1-2 weeks prior

Ureteral Stents

• Double-pigtail (JJ) stents: 5-7 Fr, 20-28 cm
• Placed post-ureteroscopy to prevent ureteral edema/obstruction

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5. Pre-operative Preparation

• Urinalysis and urine culture before every case; treat any UTI pre-operatively
• Antibiotic prophylaxis (AUA guidelines): fluoroquinolone, TMP-SMX + aminoglycoside ± ampicillin, 1st/2nd generation cephalosporin, or amoxicillin/clavulanate
• Anesthesia: general (ETT or LMA), regional (spinal), or local with sedation - patient must remain completely still during rigid URS
• Imaging: fluoroscopy (C-arm preferred over fixed unit - less scatter radiation to surgeon); some centers now perform "fluoroless" ureteroscopy for routine cases
• Position: Cystolithotomy (dorsal lithotomy) position

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6. Technique Overview

Semirigid URS Technique

1. Cystoscopy - inspect bladder, place safety guidewire
2. Introduce semirigid URS transurethrally alongside the wire
3. Advance through the ureteral orifice under direct vision (never force against resistance)
4. Progress to level of stone/pathology (restricted to distal ureter, below iliac vessels)
5. Lithotripsy and stone retrieval as indicated
6. Ureteral stent placement post-procedure

Flexible URS Technique

1. Cystoscopy - drain bladder fully (prevents scope buckling into bladder)
2. Safety guidewire placement up to renal pelvis
3. Ureteral access sheath placement (optional but recommended for renal stones)
4. Pass flexible URS through access sheath into collecting system
5. Active deflection to survey all calyceal groups
6. Holmium laser lithotripsy ("dusting" or "fragmentation + retrieval")
7. Stent placement post-procedure

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7. Complications of Ureteroscopy

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8. Contraindications

• Active untreated UTI (relative - treat and reschedule)
• Uncorrected coagulopathy (therapeutic ureteroscopy)
• Anatomical impossibility (severe ureteral stricture, urinary diversion with inaccessible ureters)
• Pregnancy is a relative contraindication for elective cases; semi-rigid URS with pneumatic lithotripsy has been safely performed in pregnancy for symptomatic ureteral stones

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9. Comparison of Ureteroscope Types

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10. Key Points Summary

• URS are classified as rigid, semirigid, or flexible based on shaft flexibility, and further as fiber-optic or digital based on imaging system
• Semirigid is the workhorse for distal ureteral stones; preferred dual working channel; tip ≤7 Fr
• Flexible is essential for proximal ureter and intrarenal collecting system; requires active deflection 270°+
• Holmium:YAG laser is the gold standard intraluminal lithotripter - works on all stone compositions, uses 200-550 µm flexible fibers compatible with flexible URS
• Safety guidewire must be in place before advancing any ureteroscope
• Ureteral access sheath reduces intrarenal pressure, improves irrigation, and allows multiple passes during flexible URS
• Stone retropulsion is the primary disadvantage of pneumatic lithotripsy - antiretropulsion devices mitigate this
• Pre-procedure urine culture + antibiotic prophylaxis is mandatory per AUA guidelines
• Ureteral stenting post-URS allows ureteral healing and prevents obstructive edema
• Single-use digital flexible ureteroscopes are gaining popularity due to consistent performance and elimination of repair costs

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