In our study comparing HoLEP and MoLEP, we could not identify any significant differences in perioperative results or postoperative complications. The overall EF was relatively high in both groups. The overall rate of complications was low, and very low for relevant complications greater than CDC grade IIIa.

In MoLEP, pulse modulation alters the shape and properties of the vapor bubble, resulting in several differences: a larger protortion of photothermic energy reaches the target tissue, resulting in a more efficient tissue vaporization and first pass hemostasis [11]. Potential advantages include decreased fiber burnback and vibration as the bubble colapses further away from the tip of the fiber [18]. The altered shape of the bubble results in a decreased amount of mechanical energy directed laterally; however, decreasing the laterally directed mechanical effect unique to Ho-YAG. Therefore, the alteration of the pulse does not come without constraints: the improved cutting and coagulation capabilities are offset by decreased mechanical energy.

With regard to complications, this series adds to the growing body of evidence that HoLEP is extremely safe in experienced hands [19]. Very few significant complications were observed. Bleeding that required intervention in the form of transurethral coagulation was seen in 3 patients (< 1,5%). No transfusions were administered. Two patients had difficulty in recatheterization after urinary retention due to blood clots in the prostatic fossa, which was resolved by flexible cystoscopy. It is not uncommon that catheterisation is challenging after HoLEP due to the steep angle at the level of the bladder neck. While there is nothing wrong with using a flexible cystoscope to overcome the bladder neck, the problem can usually be resolved by the use of a dufour tip catheter with digital rectal guidance. Unsurprisingly, there were no significant differences in complications recorded by both CDC and CCI.

Taking a look at the available studies comparing HoLEP to MoLEP, several things become evident: The results of the different series are highly variable, regardless whether MoLEP or HoLEP was used [20, 21]. The mean EF, which is a suitable parameter to describe the amount of enucleated adenoma per unit time, ranged from 1 to 4.2 g/min between studies [9,10,11,12]. Surgical experience was sufficiently high in all series.

Secondly, the one series that used the En-Bloc approach outperformed all other series in terms of EF, HT, and total OT [10] independently whether pulse modulation was used or not. This begs the question of whether the technique applied may not have a greater impact on OT than the energy source used.

Thirdly, the effect of MOSES® technology on surgical results varies between different studies. In the series by Kavrousi et al. [12], EF was equal between the groups. However, there was a significant difference in HT, which ranged from 18 min in the MoLEP group to 29 min in the HoLEP group. Interestingly, HT appeard to be exceedingly long compared to all other series. In the study by Socarrás et al. [10], EF efficiency was significantly better in the MoLEP group. In the study by Nottingham et al., a very slight advantage in enucleation time (45.9 vs. 47.1 min) and hemostasis time (8.1 vs. 10.6 min) could be registered for the MoLEP cohort. In a meta-analyis by Ramadhani et al. [20], the mean difference in OT was not statistically significant. The mean differences in HT and ET were 3.7 and 3.0 min, in favor of MoLEP. It is questionable, however, if these minor differences are clinically relevant. The meta-analysis by Gauhar et al. [21] did show a more pronounced advantage for MoLEP in terms of operation time and hemaostasis time but only included 3–4 Studies in their analysis.

The HT in our cohort was shorter than that in most other studies, probably resulting from hybrid hemostasis with laser coagulation throughout the procedure and bipolar coagulation at the end of the procedure.

Reasons why we did not see a measurable difference in perioperative outcomes may include the following: Since we exclusively used the En-Bloc technique, there were fewer extraanatomical steps in the procedure, and the 5, 7, and 12 o’clock incisions performed in three-lobe technique are probably faster with a modulated pulse. Secondly, most of the studies investigating HoLEP vs. MoLEP performed hemostasis by laser only, rather than the hybrid technique that we applied. This hybrid hemostasis is very common in Germany, although it is less common in the USA and the UK, where most comparative studies of MoLEP and HoLEP were performed. Lastly, as with any surgery, there are surgeon specific differences in the way the procedure is performed. In our experience, a strictly anatomical approach is the most important factor in having an efficient procedure with minimal blood loss and excellent functional results.

This study has limitations due to its unicentric location and as it was not randomized. We used propensity score matching to minimize the risk risk of selection bias. Furthermore, the interventions were all performed by one surgeon with high experience; therefore, the results of this trial may not be generalizable to all surgeons. Although the steep learning curve during the first 100 procedures had already been passed by the surgeon in our series, a longterm learning may still have taken place. Moreover, due to the low overall rate of complications, this study is not powered to detect slight differences in the incidence of complications or other endpoints.