Transient stress urinary incontinence is a complication commonly reported after HoLEP. Its occurrence varies in the literature from 3.3 to 26% at 3 months (Table 4). Fortunately, most cases recover within the first year . However, its assessment in several studies is based only on patient reported data (Table 4), and one possible explanation for the variation of reported SUI rates is the lack of a standard evaluation. Without the use of a validated questionnaire, incidence and prevalence of postoperative urinary incontinence could be underestimated, and precise determination of the type of incontinence is difficult . The ICIQ-SF is a validated questionnaire in male urinary incontinence that distinguishes different types of urinary incontinence and estimates their severity . The present study showed 11.4% and 10.5% de novo SUI at 1 month and 3 months respectively. The use of the same questionnaire at each follow up point confirmed the transient nature of SUI. Indeed, only 4 patients (2.6%) reported a persistent mild urinary leakage at one year despite PFMT.
Two main independent demographic risk factors for the occurrence of SUI during the first 3 postoperative months were identified: age greater than 70 years (p <0.02) and a BMI greater than 30 (p <0.007). These results confirm those of Nam et al  who reported, in a retrospective series of 391 patients, a significantly higher rate of transient SUI in patients over 65 years old. In another retrospective and multicentric series of 2346 patients, increasing age and elevated BMI were also significantly associated with urinary incontinence . Other demographic risk factors such as a history of diabetes mellitus and a pre-operative prostate volume greater than 81g have also been reported  but were not found in our study. Intrinsic sphincter insufficiency in elderly, overweight and diabetic patients could favour the occurrence of transient SUI after endoscopic enucleation .
In this study, we did not identify any intraoperative factor that could induce transient SUI. However, during HoLEP, some factors could cause an occlusion defect of the urethra-sphincter complex which leads to transient SUI: widening of the bladder neck, tearing of muscle fibres due to excessive use of mechanical thrust, heat damage to muscle fibres due to excessive use of laser energy at the apex of the adenoma, incomplete occlusion due to circumferential tearing of the proximal sphincter’s mucosa (seal effect). Elmansy et al showed that a decrease in PSA level greater than 84%, reflecting the amount of removed prostate tissue, was associated with a higher risk of stress urinary incontinence . Similarly, enucleation weight have been considered as an independent intraoperative predictive factor of urinary incontinence at 3 and 6 months. In the same way, technical difficulty like poor visibility of the operating field due to excessive bleeding was linked to a higher risk of inappropriate endoscopic manipulations and thus urethral sphincter injury [7,19,20]. Several authors have also suggested that reducing the energy delivered during enucleation, in particular when near the urethral sphincter, could minimize the risk of thermal damage without increasing operating time. Unfortunately, no consensus for the optimal setting has yet been reached.
Several HoLEP techniques have been reported since the first procedure described by Gilling  : 2-lobes technique, En-Bloc technique, white line technique[23,24], anteroposterior dissection HoLEP , Top-Down HoLEP  . In a non-randomized retrospective monocentric study, Endo and al  reported a decrease of incontinence rate (2.7% vs 25.2%) in favour of anteroposterior dissection HoLEP versus Gilling’s method. However, these results have not yet been confirmed. As described earlier, our technique is a mix of the white line and the 3-lobe techniques. Our modifications based on early apex dissection avoid stretching the urethral sphincter by first separating the adenoma from the sphincter area. Lateral lobe enucleation was carried out through the adenoma apex until reaching the capsule. Small apical adenomatous remnants were left in place as sphincter protective flaps. With this method, only 2 patients (1.3%) reported a persistent mild stress urinary incontinence requiring one pad per day at one year. However, in the absence of comparative studies, it is impossible to identify one technique that would preserve continence more safely.
In our study, HoLEP was carried out by 2 operators which had conducted at least 200 HoLEP procedures. it is well known that the learning curve affects the incidence of SUI after HoLEP [7,11]. Fifty procedures at least are necessary to master the technique . In this phase, the unassisted beginner surgeon is exposed to an increased risk of SUI by sphincter injury due to an inappropriate apex dissection [9,11,13] as well as an excessive operating time . For these reasons, increased initial case density  and structured mentorship programs (video viewing, simulator training and active proctoring) are needed to improve the safety of HoLEP procedures . Moreover, avoiding potentially complicated cases (prostate volumes greater than 80g, anticoagulated patients, patients with prostate cancer, prior prostatic radiotherapy) during the learning phase has been recommended.
The current study has several limitations, as a non-controlled study with a retrospective design and a small number of patients. In addition, there were no objective measurements, such as a pad test or a voiding diary. Finally, urodynamic tests other than uroflowmetry were not routinely performed. However, the use of the same surgical technique by two experienced operators in the same hospital and the systematic evaluation of postoperative urinary incontinence by a standardized and validated questionnaire, made it possible to reduce biases due to patients interview, learning curve and different practices.