According to the European Association of Urology guidelines , holmium laser enucleation of the prostate (HoLEP) is an established standard of care for patients suffering from lower urinary tract symptoms secondary to benign prostatic enlargement, causing bladder outlet obstruction refractory to medication.
HoLEP was introduced in the late 1990s by P. J. Gilling and M. R. Fraundorfer, combining the mini-invasiveness of the transurethral approach and the ability to obtain endoscopically the same complete anatomic enucleation of the prostatic adenoma provided by open prostatectomy, with maximal outlet desobstruction. Over the years, HoLEP has been proven to be safe and effective for the treatment of prostatic adenomas of any size , also in patients on antiplatelet/anticoagulant therapies [3,4].
THE CONCEPT OF ENDOSCOPIC ENUCLEATION OF THE PROSTATE: APPLICABLE TO ALL LASERS
Endoscopic enucleation of the prostate (EEP)  is a novel acronym accommodating all laser-based (holmium, thulium, lithium-borate ‘Greenlight,’ and diode) and nonlaser-based (monopolar, bipolar, and plasmakinetic) transurethral approaches, able to radically enucleate the obstructing prostatic adenoma and matching the durable functional results of open prostatectomy.
Among laser-based EEP the most documented one is HoLEP (PubMed search 15 November 2018: about 500 articles since 1998), followed by ThuLEP (Thulium Laser Enucleation of the Prostate, about 80 articles since 2009), GreenLEP (Lithium-borate ‘Greenlight’ Enucleation of the Prostate, about 40 articles since 2009), and DiLEP (Diode Laser Enucleation of the Prostate, 30 articles since 2011).
Laser-based EEP techniques take advantage of the different laser–tissue interactions (e.g., the efficient vaporizing ability of the ‘Greenlight’ or the effective cutting/coagulating capability of the thulium), supported to varying degrees by the blunt mechanical detachment of the adenoma from the surgical capsule (on one hand, reducing energy delivery to the capsule and related postoperative storage symptoms and on the other hand, forcing anatomical planes with resulting traction of the sphincter, risk of capsular perforations, or adenoma ruptures).
The traditional three-lobe technique (detaching first the median lobe from the verumontanum toward the bladder neck, then the two separated lateral lobes) was modified by some urologists into the two-lobe (enucleating the median lobe attached to one of the lateral lobes) and the one-lobe/en-bloc approach (‘partially-en-bloc’ technique, enucleating the adenoma in a horseshoe-like piece with a single 5 o’clock incision) (‘totally-en-bloc’ approach, with no urethral incisions, early release of the sphincteric mucosa and late opening of the bladder neck), supported by a variety of tips and tricks aiming at overcoming some procedural difficulties [2,5,6].
HOLMIUM LASER ENUCLEATION OF THE PROSTATE: THE ONLY TRUE ‘ENERGY-DRIVEN’ ENUCLEATION OF THE PROSTATE
Holmium:YAG (Ho:YAG) laser is a pulsed solid laser with a wavelength of 2140 nm, mainly absorbed by water (of irrigation, cells, and extracellular spaces), a penetration depth into tissues of 0.4 mm and an incisional depth of 0.7 mm, depending upon various settings, delivering the laser pulse through a front-firing fiber . Ho:YAG laser is efficient for the treatment of diverse soft tissue pathologies, thanks to its coagulating, vaporizing, and incising abilities, largely depending on the energy/frequency/pulse length settings and the distance between laser fiber tip and tissue (contact versus noncontact mode).
Ho:YAG laser ability to ablate/vaporize the prostatic adenoma in a near-contact mode is definitely inferior to other lasers. In fact, pure holmium laser ablation of the prostate was early abandoned in favor of HoLEP or more efficient laser-based ablating/vaporizing techniques.
On the contrary, Ho:YAG laser ability to incise is excellent. As a matter of fact, HoLEP was preceded by holmium laser resection of the prostate (HoLRP), which heavily affected the first HoLEPs, largely exploiting the incisional ability of this laser in the contact mode (unfortunately also delivering a relevant amount of energy to the capsule and acting regardless of the anatomical planes), further improved by the increased power of the latest devices up to 120/140 W and by the recent introduction of the Moses technology .
Nevertheless, Ho:YAG laser additionally has the unique ability to generate plasma bubbles of definite size and geometries at the tip of the fiber kept at a short distance (3 mm) from the tissue (noncontact mode). The laser pulse generates a rapidly expanding hot-water vapor bubble with coagulating effects, also enhancing the optical transmission of the laser beam, then collapsing and producing pressure waves able to ablate tissues and dissolve the connective bridges between adenoma and capsular plane, gently put in tension by lifting the adenoma centripetally with the tip of the resectoscope. This ‘no-touch’ approach optimizes the quality of anatomic enucleation, endoscopic vision, and progressive targeted hemostasis (the incision is surrounded by a coagulation zone, increased with greater energy irrespective to the frequency) and minimizes energy delivery to the capsular plane (one of the mechanisms possibly triggering postoperative storage symptoms, lower in our series compared to the literature) [5,7,9].
LOW-POWER ENUCLEATION: A VERSATILITY RESERVED TO HOLMIUM LASER
Since the introduction of HoLEP, urologists mainly used the 100 W Ho:YAG laser device (energy 2 J, frequency 40–50 Hz), sometimes decreasing laser energy for apical incisions. In 2015, after more than 250 ‘en-bloc no-touch’ HoLEPs performed with the traditional setting, we progressively decreased power to less than 40 W by decreasing frequency from 50 to 18 Hz. We inferred that high frequencies assimilate Ho:YAG laser to a continuous wave laser, exerting a prevailing photothermic effect on the capsule for a longer time, whereas low frequencies limit energy supply to the tissue thanks to the reduced collapse pressure of the plasma bubble, further softened by the long pulse length. After more than 250 ‘low-power en-bloc no-touch’ HoLEPs (power 39.6 W, energy 2.2 J, frequency 18 Hz, long pulse length), we concluded that this procedure is feasible, safe, and effective as the traditional ‘high-power’ approach, as recently confirmed by other authors, being coagulation unaffected, energy consumption reduced by nearly one third and early postoperative storage symptoms less intense and durable [5,7,10].
HoLEP is a continuously evolving technique, aiming at the improvement of its efficacy, safety, and durability. Optimization of the step-by-step procedure, deep knowledge of the laser technology, investigation of the clinical anatomy of both adenoma and sphincter are all crucial issues for HoLEP outcomes and diffusion among urologists .
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1. Gravas S, Cornu JN, Drake MJ, et al. Management of nonneurogenic male lower urinary tract symptoms (LUTS), incl. benign prostatic obstruction (BPO). https://uroweb.org/guideline/treatment-of-non-neurogenic-male-luts/
. [Accessed 20 March 2019].
2. Large T, Krambeck AE. Evidence-based outcomes of holmium laser enucleation of the prostate. Curr Opin Urol 2018; 28:301–308.
3. Sun J, Shi A, Tong Z, Xue W. Safety and feasibility study of holmium laser enucleation of the prostate (HoLEP) on patients receiving dual antiplatelet therapy (DAPT). World J Urol 2018; 36:271–276.
4. Rivera M, Krambeck A, Lingeman J. Holmium laser enucleation of the prostate in patients requiring anticoagulation. Curr Urol Rep 2017; 18:77(5 pages).
5. Scoffone CM, Cracco CM. High-power HoLEP: no thanks!. World J Urol 2018; 36:837–838.
6. Scoffone CM, Del Fabbro D, Figueiredo F, Cracco CM. The totally en-bloc no-touch low-power holmium laser enucleation of the prostate (HoLEP) technique. J Endourol 2018; 32:VS3–VS6.
7. Emiliani E, Talso M, Haddad M, et al. The true ablation effect of holmium YAG laser on soft tissue. J Endourol 2018; 32:230–235.
8. Elhilali MM, Badaan S, Ibrahim A, Andonian S. Use of the Moses technology to improve holmium laser lithotripsy outcomes: a preclinical study. J Endourol 2017; 31:598–604.
9. Cho KJ, Koh JS, Choi JB, Kim JC. Factors associated with early recovery of stress urinary incontinence following holmium laser enucleation of the prostate in patients with benign prostatic enlargement. Int Neurourol J 2018; 22:200–205.
10. Minagawa S, Okada S, Morikawa H. Safety and effectiveness of holmium laser enucleation of the prostate using a low-power laser. Urology 2017; 110:51–55.
11. Kampantais S, Dimopoulos P, Tasleem A, et al. Assessing the learning curve of holmium laser enucleation of prostate (HoLEP). A systematic review. Urology 2018; 120:9–22.