World Journal of Urology

, Volume 37, Issue 9, pp 1933–1939 | Cite as

Ho:YAG laser lithotripsy in non-contact mode: optimization of fiber to stone working distance to improve ablation efficiency

  • Vincent De Coninck
  • Etienne Xavier Keller
  • Paul Chiron
  • Laurian Dragos
  • Esteban Emiliani
  • Steeve Doizi
  • Laurent Berthe
  • Olivier TraxerEmail author
Original Article



To evaluate how variable working distances between the laser fiber and the stone influence ablation volume.


A laser fiber was fixed on a robotic arm perpendicular to an artificial stone. A single laser pulse was triggered at different working distances (0–2.0 mm in 0.2 mm increments) between the distal fiber tip and the stone. To achieve a measurable impact, pulse energy was set to 2 and 3 J, with either short or long pulse duration. Ablation volume was calculated with an optical microscope. Experiments were repeated five times for each setting.


Highest ablation volume was observed with a long pulse of 3 J at a working distance of 0.4 mm between the laser fiber and the stone surface (p value < 0.05). At 2 J, the highest ablation volume was noticed with a short pulse in contact mode. However, ablation volume of the latter was not significantly greater than with a long pulse of 2 J at a working distance of 0.4 mm (p value > 0.05). Compared to lithotripsy in contact mode, triggering a single long pulse at 0.4 mm increased ablation volume by 81% (p value = 0.016) at 2 J and by 89% (p value = 0.034) at 3 J.


For Ho:YAG laser lithotripsy, ablation volume may be higher in non-contact mode using long pulses, rather than in direct contact to the stone. Findings of the current study support the need of further studies of lithotripsy in non-contact mode.


Distance Ho:YAG Laser Nephrolithiasis Non-contact 






We would like to express our greatest appreciation to Prof. Gregory Altshuler, Prof. Nathaniel M. Fried and Viktoriya Vinnichenko for their valuable suggestions and proofreading of this article.

Author contributions

VDC: protocol/project development, data collection or management, data analysis, manuscript writing/editing. EXK: protocol/project development, data collection or management, data analysis, manuscript writing/editing. PC: protocol/project development, data collection or management, data analysis. LD: protocol/project development. EE: protocol/project development. SD: protocol/project development, data analysis. LB: protocol/project development, data analysis. OT: protocol/project development, data collection or management, data analysis, manuscript writing/editing.


Prof. Olivier Traxer is a consultant for Coloplast, Rocamed, Olympus, EMS and Boston Scientific. Dr. Steeve Doizi is a consultant for Coloplast. Dr. Vincent De Coninck is supported by the EUSP scholarship from the European Association of Urology and by a grant from the Belgische Vereniging voor Urologie (BVU). Dr. Etienne Xavier Keller is supported by a Travel Grant from the University Hospital Zurich and by a grant from the Kurt and Senta Herrmann Foundation.

Compliance with ethical standards

Ethical statement

We did not perform research involving human participants and/or animals.

Supplementary material

Supplementary material 1 (MP4 1604 KB)

Supplementary material 2 (MP4 1890 KB)


  1. 1.
    Kronenberg P, Traxer O (2015) Update on lasers in urology 2014: current assessment on holmium:yttrium–aluminium–garnet (Ho:YAG) laser lithotripter settings and laser fibers. World J Urol 33:463–469CrossRefPubMedGoogle Scholar
  2. 2.
    Vassar GJ, Teichman JM, Glickman RD (1998) Holmium:YAG lithotripsy efficiency varies with energy density. J Urol 160:471–476CrossRefPubMedGoogle Scholar
  3. 3.
    Kronenberg P, Traxer O (2014) In vitro fragmentation efficiency of holmium: yttrium–aluminium–garnet (YAG) laser lithotripsy—a comprehensive study encompassing different frequencies, pulse energies, total power levels and laser fibre diameters. BJU Int 114:261–267CrossRefPubMedGoogle Scholar
  4. 4.
    Talso M, Emiliani E, Haddad M et al (2016) Laser fiber and flexible ureterorenoscopy: the safety distance concept. J Endourol 30:1269–1274CrossRefPubMedGoogle Scholar
  5. 5.
    Kalra P, Le NB, Bagley D (2007) Effect of pulse width on object movement in vitro using holmium:YAG laser. J Endourol 21:228–231CrossRefPubMedGoogle Scholar
  6. 6.
    Sea J, Jonat LM, Chew BH et al (2012) Optimal power settings for holmium:YAG LITHOTRIPSY. J Urol 187:914–919CrossRefPubMedGoogle Scholar
  7. 7.
    Kronenberg P, Traxer O (2014) The truth about laser fiber diameters. Urology 84:1301–1307CrossRefPubMedGoogle Scholar
  8. 8.
    Pasqui F, Dubosq F, Tchala K et al (2004) Impact on active scope deflection and irrigation flow of all endoscopic working tools during flexible ureteroscopy. Eur Urol 45:58–64CrossRefPubMedGoogle Scholar
  9. 9.
    Kronenberg P, Traxer O (2015) Are we all doing it wrong? Influence of stripping and cleaving methods of laser fibers on laser lithotripsy performance. J Urol 193:1030–1035CrossRefPubMedGoogle Scholar
  10. 10.
    Knudsen BE, Pedro R, Hinck B, Monga M (2011) Durability of reusable holmium:YAG laser fibers: a multicenter study. J Urol 185:160–163CrossRefPubMedGoogle Scholar
  11. 11.
    Molina WR, Marchini GS, Pompeo A, Sehrt D, Kim FJ, Monga M (2014) Determinants of holmium:yttrium–aluminium–garnet laser time and energy during ureteroscopic laser lithotripsy. Urology 83:738–744CrossRefPubMedGoogle Scholar
  12. 12.
    Lu T, Xiao Q, Xia D, Ruan K, Li Z (2010) Cavitation effect of holmium laser pulse applied to ablation of hard tissue underwater. J Biomed Opt 15:048002CrossRefPubMedGoogle Scholar
  13. 13.
    De Coninck V, Keller EX, Chiron P, Doizi S, Traxer O (2018) Contact or Noncontact Laser Lithotripsy? (From: Tracey J, Gagin G, Morhardt D, et al. J Endourol 2018;32:290-295). J Endourol 32:987–988CrossRefPubMedGoogle Scholar
  14. 14.
    Emiliani E, Talso M, Cho SY et al (2017) Optimal settings for the noncontact holmium:YAG stone fragmentation popcorn technique. J Urol 198:702–706CrossRefPubMedGoogle Scholar
  15. 15.
    Chawla SN, Chang MF, Chang A, Lenoir J, Bagley DH (2008) Effectiveness of high-frequency holmium:YAG laser stone fragmentation: the "popcorn effect". J Endourol 22:645–650CrossRefPubMedGoogle Scholar
  16. 16.
    Vassar GJ, Chan KF, Teichman JM et al (1999) Holmium: YAG lithotripsy: photothermal mechanism. J Endourol 13:181–190CrossRefPubMedGoogle Scholar
  17. 17.
    Chan KF, Vassar GJ, Pfefer TJ et al (1999) Holmium:YAG laser lithotripsy: a dominant photothermal ablative mechanism with chemical decomposition of urinary calculi. Lasers Surg Med 25:22–37CrossRefPubMedGoogle Scholar
  18. 18.
    Hardy LA, Kennedy JD, Wilson CR, Irby PB, Fried NM (2017) Analysis of thulium fiber laser induced bubble dynamics for ablation of kidney stones. J Biophoton 10:1240–1249CrossRefGoogle Scholar
  19. 19.
    Sroka R, Pongratz T, Scheib G et al (2015) Impact of pulse duration on Ho:YAG laser lithotripsy: treatment aspects on the single-pulse level. World J Urol 33:479–485CrossRefPubMedGoogle Scholar
  20. 20.
    Wezel F, Hacker A, Gross AJ, Michel MS, Bach T (2010) Effect of pulse energy, frequency and length on holmium:yttrium–aluminium–garnet laser fragmentation efficiency in non-floating artificial urinary calculi. J Endourol 24:1135–1140CrossRefPubMedGoogle Scholar
  21. 21.
    Haddad M, Emiliani E, Rouchausse Y et al (2017) Impact of laser fiber tip cleavage on power output for ureteroscopy and stone treatment. World J Urol 35:1765–1770CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Sorbonne Université, GRC n°20, Groupe de Recherche Clinique Sur La Lithiase UrinaireParisFrance
  2. 2.Department of UrologyAZ KlinaBrasschaatBelgium
  3. 3.Department of UrologyUniversity Hospital Zurich, University of ZurichZurichSwitzerland
  4. 4.Department of UrologyUniversity of Medicine and Pharmacy “Victor Babes” TimişoaraTimisoaraRomania
  5. 5.Fundació Puigvert, Department of UrologyUniversidad Autonoma de BarcelonaBarcelonaSpain
  6. 6.Process and Engineering in Mechanics and Materials Laboratory (PIMM), UMR CNRS/ENSAMParisFrance

Personalised recommendations