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Flexible Ureteroscope

An actively deflectable endoscope for retrograde examination and selected treatment of the ureter, renal pelvis and calyces. Its ability to reach an individual calyx depends on anatomy, scope deflection and instruments in the channel; a semi-rigid scope may reach the proximal ureter in selected cases but generally cannot survey the calyces. Flexible ureteroscopy is central to intrarenal stone work and selected upper-tract urothelial carcinoma (UTUC) management, and may help map proximal injuries or strictures when the result will change treatment.[1][2][23]

Design​

ComponentDetail
OpticsDigital-chip and fiberoptic models coexist; imaging quality, field of view and maneuverability vary by model and setting.[3][4][23]
Outer diameterModel-specific at the tip, shaft and maximum insertion profile; do not select a sheath from tip diameter alone.
Active deflectionModel-specific and often reduced by an accessory in the working channel; lower-pole access is not guaranteed.
Working channelModel-specific; confirm the selected fiber, basket or biopsy tool against the scope instructions.
Trade-offInstrument insertion can reduce deflection and irrigation flow, which is the main operative constraint.
LightDigital distal-LED and fiber-optic illumination systems both exist; use the matching processor/light system.

For a concrete current example, Ambu aScope 5 Uretero lists a 7.9-Fr distal tip, 8.1-Fr insertion cord, 9.0-Fr maximum insertion profile, 3.6-Fr channel and 270°/270° deflection with distal LEDs. These are that model's specifications, not a class standard; its datasheet warns that channel width alone does not guarantee accessory compatibility.[24]

Single-use vs reusable​

Single-use scopes became widely available after the 2016 LithoVue launch. In Belkovsky's 2024 synthesis of 12 stone-surgery studies, measured stone-free rate, operating time, postoperative fever and UTI did not differ significantly between the compared disposable and reusable scopes; that is not proof that every model is equivalent.[5] Image quality and maneuverability comparisons remain device- and method-specific.[6] Rege's 2026 nine-platform comparison is a performance study, not a universal purchasing ranking.[7]

Ureteral access sheath (UAS)​

A ureteral access sheath can permit repeated passage, outflow and fragment retrieval. The effect on intrarenal pressure depends on scope-to-sheath clearance, irrigation, suction, sheath position and anatomy; it does not guarantee a safe pressure. Insertion can injure the ureter, especially when a larger sheath meets an unstented tight ureter. Sheathless access or staging may be preferable to forcing passage. Flexible or navigable suction sheaths can aspirate debris and improve outflow in selected stone procedures, but their stone-trial results do not establish benefit in reconstructed tracts or UTUC.[8][9][23]

Reconstructive-Urology and Functional-Urology Uses​

Flexible deflection is particularly useful for renal-pelvic and calyceal work; a semi-rigid scope may still treat selected proximal-ureteral pathology.

Upper-tract urothelial carcinoma (UTUC) endoscopic management​

  • Diagnostic ureteroscopy with selective biopsy may define location, grade and focality when imaging or cytology leave a management question. EAU 2026 strongly recommends diagnostic ureteroscopy when imaging and voided cytology are not sufficient for diagnosis or risk stratification. Its text reports that biopsy determines grade in over 90% of cases, that under-grading and under-staging occur compared with nephroureterectomy specimens, and that biopsy at ureteroscopy has been associated with later intravesical recurrence. Integrate imaging, cytology and risk stratification rather than treating the endoscopic appearance as definitive.[12][13][25]
  • Endoscopic laser ablation is a kidney-sparing option for appropriately selected low-risk UTUC after shared decision-making. EAU 2026 strongly recommends offering kidney-sparing management as the primary option in low-risk tumors and states that ablation should be considered. It notes that survival is comparable to nephroureterectomy at the cost of more local recurrence and repeat procedures, that about one in two patients has ipsilateral recurrence within two years, and that a flexible ureteroscope under 9 Fr is useful. For high-risk disease it allows ureteroscopic laser ablation or segmental ureterectomy case by case, in imperative settings such as solitary kidney, bilateral disease or severe CKD. A fixed “low-grade, unifocal, < 2 cm” rule does not reproduce the AUA or current EAU risk framework: size, grade, invasion, focality, access and an imperative need to preserve the kidney all matter. EAU states that laser is the preferred energy but that data on optimal laser type and settings are lacking; excessive power can injure normal tissue.[13][14][25][26]
  • Instillation is a separate treatment decision. Jelmyto (mitomycin gel) is labeled for adult low-grade UTUC and pyelocalyceal use only (weekly for six weeks by ureteral catheter or nephrostomy tube). Its label warns of ureteric obstruction and contraindicates use with bladder or upper-tract perforation. It is not an automatic adjunct to laser treatment of a ureteral lesion. BCG or mitomycin upper-tract instillations after complete eradication, including for CIS, have limited heterogeneous evidence and require assessment for leakage, obstruction and infection.[25][27]
  • Surveillance after endoscopic management includes early second-look ureteroscopy and continued risk-adapted follow-up because residual disease and recurrence are common; EAU 2026 gives a weak recommendation for second-look ureteroscopy within eight weeks of initial endoscopic treatment; it cites series in which up to nearly half of patients had residual or recurrent tumor at that procedure.[15][25]

Proximal-ureteral and intrarenal stricture work​

  • Diagnostic mapping of stricture length / location through the proximal ureter and UPJ.
  • Endoscopic incision or dilation with drainage can be considered for selected short strictures, but length, ischemia or radiation injury, renal function and prior repair affect durability. A radiation-associated stricture is not inherently a favorable endoscopic target; compare reconstruction or other drainage when appropriate.

Iatrogenic ureteral injury after pelvic surgery​

  • Retrograde access for guidewire passage and stent placement through the renal pelvis when the injury extends proximally beyond the semi-rigid scope's reach.
  • Diagnostic mapping to define the level or severity of injury before deciding on endoscopic versus open reconstructive management.

Post-reconstruction surveillance​

  • After pyeloplasty, ureteroureterostomy, reimplantation or ileal-ureter reconstruction, fURS can answer a specific suspected-anastomotic problem. It is not routine surveillance for every repair; imaging and follow-up depend on the operation and clinical question.

Stone management (out-of-scope as primary topic; covered for completeness)​

  • For completeness, EAU 2026 strongly recommends PCNL first-line for renal stones > 2 cm (LE 1a) and, where PCNL is not an option, flexible ureteroscopy or SWL, with a higher chance of a follow-up procedure and stent. For lower-pole stones it strongly recommends PCNL or retrograde intrarenal surgery even above 1 cm, because SWL efficacy is limited. These are not one-size-fits-all size cutoffs.[16][23]

Laser Lithotripsy Strategies​

These are stone-fragmentation concepts only, not settings or techniques for UTUC ablation. Actual energy, frequency, fiber, irrigation and thermal precautions depend on the laser and scope instructions, stone, anatomy and outflow. EAU warns that both Ho:YAG and TFL can generate injurious heat with inadequate irrigation.[23]

StrategySettingsMechanism
DustingLower pulse energy / higher frequencyProduces small fragments; residual dust may require follow-up rather than assuming complete passage
Fragmentation + extractionHigher pulse energy / lower frequencyProduces retrievable fragments; extraction under direct vision
PopcorningNon-contact in confined calyxTurbulence propels fragments back into beam

In Gauhar's 2025 prospective observational FANS cohort (704 adults, 21 centers), 30-day complete clearance was 69.4% with dusting versus 53.9% with popcorning, and reintervention was 2.1% versus 5.7%. The popcorning group had larger and denser stones (> 2 cm in 20.7% versus 10.7%). Treatment choice and laser type were not randomized, and laser technology was a stronger predictor of clearance than lasing strategy. The associated thulium-fiber-laser finding cannot establish that TFL is causally superior to Ho:YAG or that it should be used for UTUC.[10] See Cabo 2025 and Matlaga 2018 for the stone-strategy framework.[11][17]

Semi-Rigid vs Flexible Ureteroscope​

FeatureSemi-rigidFlexible
TipModel-specific, no active deflectionModel-specific active deflection
Renal-pelvis / calyceal accessMay reach proximal ureter or pelvis in selected anatomy; cannot reliably inspect calycesDesigned for renal-pelvic/calyceal work, with anatomy-dependent limits
Working channelModel-specific; some straight channels accept rigid probesModel-specific; flexible instruments only
Rigid lithotripsy probesYes (offset-lens)No
Distal/proximal stone resultsStudy-population and stone-location dependentStudy-population and stone-location dependent; do not compare unmatched registries as a head-to-head trial
Durability / costOften lower repair burden, but model/volume dependentReusable repair burden or single-use per-case cost; local comparison needed
Typical roleFirst entry, distal / mid ureterProximal ureter, pelvis, calyces, UTUC ablation

When distal pathology requires it, semi-rigid inspection may precede flexible URS and can provide optical dilation. Do not routinely instrument simply to “dilate” a tight ureter; if access fails, EAU describes stenting and returning after approximately 7–14 days.[23]

Outcomes​

SeriesnSettingStone-free / outcome
CROES URS Global[18]11,885Mixed ureteroscopic registry (ureteral and renal stones; not flexible-only)Overall stone-free rate 85.6%; complications 3.5%, mostly Clavien I–II; not a flexible-scope benchmark
Skolarikos 2015 CROES solitary[19]1,210Solitary renal stone, flexible URSSingle-session SFR 90% (< 10 mm), 80% (< 15 mm) and 30% (> 20 mm)
Giusti 2016 single-center[2]316Mean 16.5 mmPrimary SFR 79.1%; 91.5% after up to three procedures; mean OR ~ 73 min
Huang 2020[20]251Renal stones ≥ 2 cm (mean 2.7 cm), single-institution retrospectiveSFR 61.9%, 82.9% and 89.5% after the first, second and third procedure (mean 1.4 procedures); 58.3% for stones > 4 cm after a mean of 2.3 procedures
Fankhauser 2018 propensity-matched fURS vs SWL[21]1,282 (283 URS)Untreated renal stones, retrospective84% (fURS) vs 71% (SWL) SFR; freedom from reintervention 79% vs 55%
FLEXOR registry[22]6,669RIRS practice patternsReported complications 8.0%; UAS-associated injury 1.8% and sepsis/ICU 1.3% in that cohort

These cohorts differ in stone burden, imaging definition, follow-up and whether ureteral or renal cases were included. Their percentages should not be used as a direct scope-comparison or patient-specific prediction.

Safety Profile​

  • Postoperative fever. Incidence varies with study population and definition; assess infection risk before instrumentation.[22][23]
  • Sepsis or ICU admission. Reported in 1.3% of the FLEXOR stone cohort; this is not a general fURS estimate.[22]
  • Ureteric injury from UAS. Grades and ascertainment vary widely; the 1.8% FLEXOR report is not a universal risk estimate. Prospective sheath studies found many more minor visible injuries when the entire wall was inspected.[8][9][22][23]
  • Ureteral perforation. Uncommon but consequential. Suction may improve outflow; it does not eliminate pressure, infection or injury risk.[23]
  • Ureteral stricture. Late event associated with ureteral injury, impacted stones and prolonged instrumentation; sheath use can be confounded by case difficulty. In one small grade-3 injury subgroup, 2/15 (13.3%) developed stricture, which is not a general risk estimate (see the semi-rigid ureteroscope page for cohort context).

Practical Pearls​

  • Pre-stenting is selective and can facilitate later access. If safe access is impossible, stenting and returning in about 7–14 days is an EAU-described option. Balance this against stent symptoms and infection risk with prolonged dwell.[23]
  • Smallest compatible UAS that meets the case need if a sheath is used; do not force insertion. FANS or suction is a selective stone-case adjunct and does not assure pressure control.[23]
  • Sequential approach when indicated. Semi-rigid first for a distal target or optical access assessment; do not force a scope through resistance.[23]
  • Laser choice for stones. Ho:YAG and TFL are both accepted; observational clearance associations do not override patient, anatomy, thermal and equipment considerations.[10][23]
  • For UTUC. Obtain an adequate diagnostic and risk assessment and plan whether staged histology is needed. Same-setting ablation is not automatically appropriate; subsequent second-look and surveillance are needed.[13][25]

Limitations​

  • Cost. Reusable scopes incur substantial repair cost; single-use scopes have higher per-case cost.
  • Working-channel trade-off. Every instrument inserted reduces deflection and irrigation; choose the smallest adequate fiber or basket.
  • Stone burden. PCNL is generally first-line above 2 cm; staged flexible treatment remains an alternative in selected cases when PCNL or SWL are unsuitable.[23]
  • Tight or impacted ureter. Stop at resistance; a smaller instrument, sheathless approach, drainage or staged access may be safer than dilation or forced passage.[23]

See also: Semi-Rigid Ureteroscope, Rigid Cystoscope, Flexible Cystoscope, Guidewires, Open-Ended Ureteral Catheters, Double-J Stent, Nephrostomy Tube.

References​

1. Doizi S, Traxer O. "Flexible ureteroscopy: technique, tips and tricks." Urolithiasis. 2018;46(1):47–58. doi:10.1007/s00240-017-1030-x

2. Giusti G, Proietti S, Villa L, et al. "Current standard technique for modern flexible ureteroscopy: tips and tricks." Eur Urol. 2016;70(1):188–94. doi:10.1016/j.eururo.2016.03.035

3. Dale J, Kaplan AG, Radvak D, et al. "Evaluation of a novel single-use flexible ureteroscope." J Endourol. 2021;35(6):903–7. doi:10.1089/end.2016.0237

4. Vaccaro C, Lorusso V, Palmisano F, et al. "Single-use flexible ureteroscopes: how difficult is it today to stay up to date? A pictorial review of instruments available in Europe in 2023." J Clin Med. 2023;12(24):7648. doi:10.3390/jcm12247648

5. Belkovsky M, Passerotti CC, Maia RS, et al. "Comparing outcomes of single-use vs reusable ureteroscopes: a systematic review and meta-analysis." Urolithiasis. 2024;52(1):37. doi:10.1007/s00240-024-01537-8

6. Bragaru M, Multescu R, Geavlete P, Popescu R, Geavlete B. "Comparison of flexible ureteroscope performance between reusable and single-use models." J Clin Med. 2023;12(3):1093. doi:10.3390/jcm12031093

7. Rege R, Hassig S, Patel S, et al. "A comparison of real-world utility and video quality in commercially available single-use ureteroscopes." J Endourol. 2026;40(1):9–16. doi:10.1177/08927790251390908

8. Kaplan AG, Lipkin ME, Scales CD, Preminger GM. "Use of ureteral access sheaths in ureteroscopy." Nat Rev Urol. 2016;13(3):135–40. doi:10.1038/nrurol.2015.271

9. De Coninck V, Keller EX, Rodríguez-Monsalve M, et al. "Systematic review of ureteral access sheaths: facts and myths." BJU Int. 2018;122(6):959–69. doi:10.1111/bju.14389

10. Gauhar V, Giulioni C, Falsetti F, et al. "Lasing strategy and its influence on 30-day operative outcomes in flexible ureteroscopy with FANS: inferences from a real-world prospective multicenter study by EAU-Endourology and AUSET." World J Urol. 2025;43(1):633. doi:10.1007/s00345-025-06012-6

11. Cabo J, Ballantyne C, Edmonds V, Stern KL. "Laser lithotripsy strategies: fragmenting, popcorning, dusting, and how intrarenal pressure should be considered." Urol Clin North Am. 2025;52(3):375–89. doi:10.1016/j.ucl.2025.04.004

12. National Comprehensive Cancer Network. "Bladder Cancer (Upper Tract Urothelial Carcinoma sections)." Updated 2026.

13. Coleman JA, Clark PE, Bixler BR, et al. "Diagnosis and management of non-metastatic upper tract urothelial carcinoma: AUA/SUO guideline." J Urol. 2023;209(6):1071–81. doi:10.1097/JU.0000000000003480

14. Inamoto T, Watanabe S, Tsuchiya Y, et al. "Current kidney-preserving strategies for upper tract urothelial carcinoma." Int J Urol. 2025. doi:10.1111/iju.70243

15. Sydén F, Baard J, Bultitude M, et al. "Consultation on UTUC II Stockholm 2022: diagnostics, prognostication, and follow-up — where are we today?" World J Urol. 2023;41(12):3395–403. doi:10.1007/s00345-023-04530-9

16. Skolarikos A, Geraghty R, Somani B, et al. "European Association of Urology guidelines on the diagnosis and treatment of urolithiasis." Eur Urol. 2025;88(1):64–75. doi:10.1016/j.eururo.2025.03.011

17. Matlaga BR, Chew B, Eisner B, et al. "Ureteroscopic laser lithotripsy: a review of dusting vs fragmentation with extraction." J Endourol. 2018;32(1):1–6. doi:10.1089/end.2017.0641

18. de la Rosette J, Denstedt J, Geavlete P, et al. "The Clinical Research Office of the Endourological Society Ureteroscopy Global Study: indications, complications, and outcomes in 11,885 patients." J Endourol. 2014;28(2):131–9. doi:10.1089/end.2013.0436

19. Skolarikos A, Gross AJ, Krebs A, et al. "Outcomes of flexible ureterorenoscopy for solitary renal stones in the CROES URS Global Study." J Urol. 2015;194(1):137–43. doi:10.1016/j.juro.2015.01.112

20. Huang JS, Xie J, Huang XJ, et al. "Flexible ureteroscopy and laser lithotripsy for renal stones 2 cm or greater: a single institutional experience." Medicine. 2020;99(43):e22704. doi:10.1097/MD.0000000000022704

21. Fankhauser CD, Hermanns T, Lieger L, et al. "Extracorporeal shock wave lithotripsy versus flexible ureterorenoscopy in the treatment of untreated renal calculi." Clin Kidney J. 2018;11(3):364–9. doi:10.1093/ckj/sfx151

22. Gauhar V, Chew BH, Traxer O, et al. "Indications, preferences, global practice patterns and outcomes in retrograde intrarenal surgery (RIRS) for renal stones in adults: results from a multicenter database of 6669 patients of the Global FLEXible Ureteroscopy Outcomes Registry (FLEXOR)." World J Urol. 2023;41(2):567–74. doi:10.1007/s00345-022-04257-z

23. European Association of Urology. EAU Guidelines on Urolithiasis. 2026. Ureteroscopy, access, laser, stenting and stone-selection sections.

24. Ambu. aScope 5 Uretero datasheet, V03, September 2024. Manufacturer specifications and accessory caveat.

25. European Association of Urology. EAU Guidelines on Upper Urinary Tract Urothelial Cell Carcinoma. 2026. Disease management.

26. European Association of Urology. EAU Guidelines on Upper Urinary Tract Urothelial Cell Carcinoma. 2026. Risk stratification.

27. US Food and Drug Administration. JELMYTO (mitomycin) prescribing information, label effective July 2025. DailyMed.