Association between lateral lobe enucleation time and urethral stricture after Holmium Laser Enucleation of the Prostate (HoLEP): a retrospective cohort study

Abstract

Background

To evaluate whether lateral lobe enucleation time is associated with postoperative urethral stricture after holmium laser enucleation of the prostate (HoLEP).

Methods

We retrospectively reviewed 519 HoLEP procedures performed between January 2023 and January 2025. To minimize operator- and technique-related heterogeneity, we included only standardized trilobar HoLEP cases performed by a single high-volume surgeon (> 400 prior cases); procedures by other surgeons and/or non-trilobar approaches were excluded. Urethral stricture was defined as symptomatic urethral narrowing confirmed endoscopically. The prespecified exposure was total lateral lobe enucleation time (sum of both lateral lobes), modeled per 10-minute increase. Associations were evaluated using Firth bias-reduced logistic regression.

Results

Among 168 eligible patients, 8 (4.8%) developed urethral stricture. Total lateral lobe enucleation time was longer in the stricture group (median 70.0 [IQR, 53.0–70.0] vs. 32.5 [IQR, 26.0–45.2] minutes; p = 0.017). Follow-up duration differed between groups (p = 0.002). In multivariable Firth regression adjusting for age (per 10 years), prostate volume (per 10 g), and preoperative urethral catheterization, lateral lobe enucleation time remained independently associated with stricture (adjusted OR, 1.78 per 10 min; 95% CI, 1.24–2.53; p = 0.002). Preoperative urethral catheterization was also associated (adjusted OR, 4.48; 95% CI, 1.03–19.50; p = 0.045).

Conclusions

Longer total lateral lobe enucleation time is independently associated with urethral stricture after HoLEP and may be related to increased instrument angulation and mechanical stress at the urethral fulcrum.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s12894-026-02286-z.

Background

Benign prostatic hyperplasia (BPH) is a major cause of bladder outlet obstruction and lower urinary tract symptoms in aging men, and surgery remains indicated for refractory symptoms or BPH-related complications. Holmium laser enucleation of the prostate (HoLEP) is a widely adopted, size-independent endoscopic enucleation technique with durable functional improvement and an acceptable overall safety profile [1, 2].

Although uncommon, postoperative urethral stricture remains a clinically meaningful adverse event after transurethral BPH surgery, potentially requiring additional interventions and attenuating functional gains [3]. Comparative evidence suggests that urethral stricture rates after HoLEP may be similar to those after transurethral resection of the prostate (TURP), indicating that this complication remains relevant across transurethral modalities [4].

In contemporary HoLEP practice, urethral stricture is often reported as an overall incidence, and fewer studies have examined perioperative determinants that could refine risk stratification. Prior work has largely relied on global time metrics (total operative or overall enucleation time), with longer procedures associated with higher stricture risk [4, 5]. However, global measures do not capture step-specific workload. In a standardized trilobar approach, lateral lobe dissection may plausibly involve greater instrument angulation at the urethral fulcrum, increasing mechanical stress on the urethra. Lobe-specific enucleation time—particularly lateral lobe time—has not been well characterized in relation to subsequent urethral stricture. Therefore, we investigated perioperative factors associated with postoperative urethral stricture after HoLEP, with a specific focus on total lateral lobe enucleation time.

Methods

Study design and patient selection

This single-center retrospective cohort study was conducted to evaluate postoperative urethral stricture after holmium laser enucleation of the prostate (HoLEP). All HoLEP procedures performed between January 2023 and January 2025 were screened (n = 519). To minimize operator- and technique-related heterogeneity, the analytic cohort was restricted to standardized trilobar HoLEP procedures performed by a single high-volume surgeon with more than 400 prior HoLEP cases. Patients in whom initial passage of the 26-Fr resectoscope was not feasible and urethral dilation or internal urethrotomy was required to obtain transurethral access were excluded from the study. Additional exclusion criteria included any prior prostate surgery and any concomitant urethral procedure performed at the time of HoLEP. After application of predefined exclusion criteria, 351 procedures were excluded and 168 procedures constituted the final analytic cohort (Fig. 1).

Fig. 1.

Flow diagram of patient selection. All HoLEP procedures performed between January 2023 and January 2025 were screened (n=519); after exclusions (n=351), 168 patients were included in the final analytic cohort. Abbreviations: HoLEP, holmium laser enucleation of the prostate; RT, radiotherapy

Surgical technique and equipment

All procedures were performed using a 26-Fr SHARK continuous-flow resectoscope (Richard Wolf GmbH, Knittlingen, Germany) equipped with the standard manufacturer-supplied sheath; no sheath modification was used. Normal saline was used for irrigation. No patient included in the analytic cohort underwent urethral dilation or internal urethrotomy to facilitate resectoscope insertion. Enucleation and morcellation were conducted using an integrated holmium: YAG laser system (MultiPulse HoPLUS 150; Jena Surgical, Jena, Germany) equipped with a built-in morcellation module; no standalone morcellator was used. A 550-µm laser fiber was used in all cases. Laser settings were standardized across the cohort, with enucleation performed at 2.0 J and 40 Hz (80 W) in short-pulse mode and coagulation at 2.0 J and 35 Hz (70 W) in long-pulse mode. Morcellation was performed after routine device setup and safety checks, using high aspiration, a rotation speed of 2,000 rpm, and an oscillation frequency of 3.0 Hz.

Data collection and operative time metrics

Baseline, perioperative, and follow-up data were extracted from electronic medical records and operative documentation using a standardized data collection form. Preoperative variables included age, prostate-specific antigen (PSA), prostate volume, PSA density, prior medical therapy for benign prostatic hyperplasia, preoperative urethral catheterization status, prior prostate biopsy, and comorbidities (hypertension, diabetes mellitus, and coronary artery disease). Preoperative urethral catheterization was not used as an exclusion criterion because it reflects baseline urinary retention and was considered clinically relevant; therefore, catheterization status was recorded for all patients and included as a covariate in multivariable analyses.

Operative variables were obtained from standardized operative reports and time logs and included lobe-specific enucleation times (median lobe, left lateral lobe, and right lateral lobe), total lateral lobe enucleation time, total enucleation time, morcellation time, total operative time, and enucleated tissue weight. Total lateral lobe enucleation time was defined a priori as the sum of left and right lateral lobe enucleation times, and total enucleation time as the sum of median lobe and total lateral lobe enucleation times. Postoperative in-hospital variables included urethral catheterization duration and length of hospital stay.

Functional outcomes were assessed when available. In patients presenting with an indwelling urethral catheter, preoperative voiding-based assessments were not feasible. Symptom severity was evaluated using the International Prostate Symptom Score (IPSS). Uroflowmetry parameters included maximum flow rate (Qmax), average flow rate (Qaverage), voided volume, and postvoid residual urine (PVR).

Outcome definition and follow-up

The primary endpoint was postoperative urethral stricture. During follow-up, patients presenting with recurrent or persistent lower urinary tract symptoms suggestive of obstruction underwent clinical evaluation. When urethral stricture was suspected, the diagnosis was confirmed by office-based cystoscopy under local anesthesia. Stricture location was recorded at the time of cystoscopy and categorized relative to the external urethral sphincter. Follow-up duration was calculated from the date of the index HoLEP to the last documented outpatient visit. For patients who developed urethral stricture, follow-up was censored at the date of endoscopic confirmation; therefore, observed follow-up duration was shorter in patients who developed the endpoint.

Statistical analysis

Continuous variables are presented as median (interquartile range) and categorical variables as number (percentage). Between-group comparisons were performed using the Mann–Whitney U test for continuous variables and Fisher’s exact test for categorical variables. Given the small number of urethral stricture events, associations between enucleation time variables (median lobe, left lateral lobe, right lateral lobe, and total lateral lobe enucleation time) and postoperative urethral stricture were examined using Firth’s penalized (bias-reduced) logistic regression to mitigate small-sample bias. Odds ratios (ORs) with 95% confidence intervals (CIs) are reported, and time-based predictors were modeled per 10-minute increase to facilitate interpretability. All statistical tests were two-sided, and p < 0.05 was considered statistically significant. Statistical analyses were performed using IBM SPSS Statistics (version 22; IBM Corp., Armonk, NY, USA).

For multivariable modeling, total lateral lobe enucleation time was prespecified as the primary exposure. Age (per 10 years), prostate volume (per 10 g), and preoperative urethral catheterization status were included as covariates based on clinical relevance. Total enucleation time was not entered concurrently because of collinearity with total lateral lobe enucleation time. Prespecified sensitivity analyses were conducted using alternative covariate specifications, including additional adjustment for median lobe enucleation time and substitution of enucleated tissue weight for prostate volume.

Results

Among 168 patients in the final analytic cohort, postoperative urethral stricture was identified in 8 patients (4.8%) during follow-up. On office cystoscopy, all strictures were located immediately distal to the external urethral sphincter, corresponding to the proximal bulbar urethra at the bulbomembranous junction; one patient also had an additional stricture at the fossa navicularis.

Patient characteristics and perioperative outcomes

Patient characteristics by stricture status are summarized in Table 1. Overall, baseline demographic and clinical variables were similar between groups. Preoperative urethral catheterization was more common among patients who developed urethral stricture than among those who did not (50.0% vs. 23.8%), although this difference did not reach statistical significance in unadjusted comparison (p = 0.109).

Table 1.

Patient characteristics by postoperative urethral stricture status

Variables	No stricture (n = 160)	Stricture (n = 8)	p-value
Preoperative variables
Age (years)	67.0 (62.0–73.0)	70.0 (62.5–77.0)	0.493
PSA (ng/mL)	3.3 (2.0–5.8)	3.3 (3.1–3.9)	0.597
Prostate volume (g)	85.5 (60.0–132.0)	75.0 (65.0–92.5)	0.941
PSA density (ng/mL/g)	0.0367 (0.0208–0.0747)	0.0508 (0.0318–0.0508)	0.858
Preoperative medical therapy for BPH	152 (95.0%)	8 (100.0%)	1.000
Preoperative urethral catheter	38 (23.8%)	4 (50.0%)	0.109
Prior prostatic biopsy	68 (42.5%)	2 (25.0%)	0.471
Hypertension	76 (47.5%)	2 (25.0%)	0.287
Diabetes mellitus	26 (16.2%)	0 (0.0%)	0.611
Coronary artery disease	36 (22.5%)	0 (0.0%)	0.204
Perioperative variables
Median lobe enucleation time (min)	9.0 (5.0–14.0)	15.0 (11.8–15.0)	0.102
Left lobe enucleation time (min)	15.0 (12.0–21.0)	35.0 (17.5–35.0)	0.034
Right lobe enucleation time (min)	16.0 (12.0–23.0)	35.0 (28.8–37.2)	0.021
Total lateral lobe enucleation time (min)	32.5 (26.0–45.2)	70.0 (53.0–70.0)	0.017
Total enucleation time (min)	41.5 (32.0–57.5)	85.0 (65.5–85.0)	0.014
Morcellation time (min)	9.0 (5.0–10.0)	10.0 (6.0–10.0)	0.805
Surgery time (min)	50.5 (40.0–70.0)	95.0 (78.2–97.2)	0.034
Enucleated tissue weight (g)	53.0 (34.2–69.0)	95.0 (47.5–95.0)	0.069
Postoperative variables
Postoperative catheterization duration (days)	4.0 (3.0–5.2)	2.0 (1.0–5.0)	0.062
Hospitalization duration (days)	1.0 (1.0–1.0)	1.0 (1.0–1.0)	0.156
Follow-up duration (months)	12.0 (12.0–18.0)	8.5 (6.8–10.2)	0.002

Continuous variables are presented as median (interquartile range) and categorical variables as number (percentage). P values are exploratory and were calculated using Mann–Whitney U test for continuous variables and Fisher’s exact test for categorical variables. Bold p-values indicate statistical significance (p ≤ 0.05)

Perioperative time metrics differed by stricture status (Table 1). Left and right lateral lobe enucleation times, as well as total lateral lobe enucleation time, were longer among patients who developed urethral stricture. Total enucleation time and overall operative time were also longer in the stricture group. In contrast, median lobe enucleation time and morcellation time did not differ significantly between groups, while enucleated tissue weight showed a non-significant trend toward higher values among patients with stricture.

Postoperative catheterization duration and length of hospitalization were similar between groups (Table 1). Observed follow-up duration was shorter in the urethral stricture group (Table 1), reflecting censoring at the time of endoscopic confirmation.

Functional outcomes

Preoperative functional assessments were available in a subset of patients because uroflowmetry-based measures could not be obtained in individuals presenting with an indwelling urethral catheter (Table 2). Within the available subset (no stricture, n = 122; stricture, n = 4), patients who later developed urethral stricture had lower preoperative IPSS and higher baseline Qmax (Table 2).

Table 2.

Preoperative and postoperative functional parameters according to urethral stricture status

Parameters	No stricture	Stricture	p-value
Preoperative parameters	n = 122	n = 4
Preoperative IPSS	26.0 (23.2–28.8)	21.5 (20.8–22.0)	0.008
Preoperative Qmax	8.0 (5.9–10.8)	12.6 (12.0–13.6)	0.013
Preoperative Qaverage	4.7 (3.1–6.0)	5.1 (4.0–6.3)	0.478
Preoperative Voided Volume	168.0 (116.5–250.0)	257.0 (233.8–292.8)	0.066
Preoperative PVR	120.0 (70.0–160.0)	187.5 (140.0–225.0)	0.096
Postoperative parameters	n = 160	n = 8
Postoperative IPSS	9.0 (7.0–11.0)	24.0 (21.8–25.2)	< 0.001
Postoperative Qmax	16.5 (14.7–22.7)	4.5 (4.3–4.8)	< 0.001
Postoperative Qaverage	10.0 (8.6–13.5)	3.2 (3.1–3.3)	< 0.001
Postoperative Voided Volume	220.0 (175.0–299.0)	157.0 (148.0–162.2)	0.008
Postoperative PVR	20.0 (0.0–50.0)	115.5 (107.0–182.0)	< 0.001

Values are median (interquartile range). P values are exploratory and were calculated using Mann–WhitneyU test

At postoperative assessment (no stricture, n = 160; stricture, n = 8), patient-reported symptoms and uroflowmetry outcomes were markedly worse among patients with urethral stricture (Table 2). The stricture group demonstrated higher postoperative IPSS and substantially reduced urinary flow (Qmax and Qaverage), accompanied by lower voided volume and higher postvoid residual urine (all p-values shown in Table 2).

Association between enucleation time metrics and urethral stricture

In unadjusted Firth bias-reduced logistic regression models, longer lateral lobe enucleation times were associated with higher odds of postoperative urethral stricture (Table 3). Left and right lateral lobe enucleation times were each significantly associated with stricture per 10-minute increase (OR, 2.71 and 2.03, respectively; both p = 0.005). Total lateral lobe enucleation time was similarly associated (OR, 1.71 per 10 min; p = 0.003). Median lobe enucleation time was not significantly associated with stricture in the unadjusted model (OR, 2.76; p = 0.120).

Table 3.

Unadjusted Firth bias-reduced logistic regression analyses of enucleation times for predicting postoperative urethral stricture

Predictor (per + 10 min)	Unadjusted OR (95% CI)	p-value
Left lobe enucleation time	2.71 (1.36–5.40)	0.005
Right lobe enucleation time	2.03 (1.24–3.31)	0.005
Median lobe enucleation time	2.76 (0.77–9.90)	0.120
Total lateral lobe enucleation time	1.71 (1.21–2.42)	0.003

Each predictor was modeled per 10-minute increase

In the prespecified multivariable Firth model adjusting for age, prostate volume, and preoperative urethral catheterization, total lateral lobe enucleation time remained independently associated with urethral stricture (adjusted OR, 1.78 per 10 min; 95% CI, 1.24–2.53; p = 0.002) (Table 4). Preoperative urethral catheterization was also associated with higher odds of stricture (adjusted OR, 4.48; 95% CI, 1.03–19.50; p = 0.045), whereas age and prostate volume were not (Table 4). Total enucleation time was not included in the model because of collinearity with total lateral lobe enucleation time.

Table 4.

Adjusted predictors of postoperative urethral stricture using Firth bias-reduced logistic regression

Predictor	Adjusted OR (95% CI)	p-value
Total lateral lobe enucleation time (per + 10 min)	1.78 (1.24–2.53)	0.002
Age (per + 10 years)	1.17 (0.52–2.64)	0.712
Preoperative prostate volume (per + 10 g)	1.03 (0.87–1.23)	0.716
Preoperative urethral catheter (yes)	4.48 (1.03–19.50)	0.045

Total lateral lobe enucleation time, age, and prostate volume were modeled as continuous variables and scaled per 10-minute, 10-year, and 10-g increases, respectively. Total enucleation time was not included in the model because of high collinearity with total lateral lobe enucleation time

Prespecified sensitivity analyses demonstrated consistent associations across alternative model specifications (Table 5). The association between total lateral lobe enucleation time and urethral stricture remained significant after additional adjustment for median lobe enucleation time (OR, 1.68 per 10 min; p = 0.005) and when enucleated tissue weight was substituted for prostate volume (OR, 1.75 per 10 min; p = 0.004).

Table 5.

Sensitivity of the enucleation time-urethral stricture association across alternative Firth logistic models

Model	Adjustment set	OR per + 10 min (95% CI)	p-value
Model A	Unadjusted	1.71 (1.21–2.42)	0.003
Model B	Age (+ 10 y), prostate volume (+ 10 g), preoperative urethral catheter	1.78 (1.24–2.53)	0.002
Model B + median lobe time	Model B plus median lobe enucleation time (+ 10 min)	1.68 (1.17–2.41)	0.005
Model B with tissue weight	Age (+ 10 y), tissue weight (+ 10 g), preoperative urethral catheter	1.75 (1.19–2.56)	0.004

Odds ratios correspond to a 10-minute increase in total lateral lobe enucleation time

Discussion

In this technique-standardized HoLEP cohort, postoperative urethral stricture occurred in 4.8% (8/168) and was associated with clinically meaningful worsening in postoperative symptoms and uroflowmetry outcomes (Table 2). Most prior HoLEP studies have examined stricture risk using aggregate operative measures (e.g., total operative or enucleation time). In contrast, our step-resolved analyses identify total lateral lobe enucleation time as a procedure-specific metric independently associated with subsequent urethral stricture, thereby localizing technical workload within the trilobar approach to the lateral dissection phase.

In unadjusted Firth bias-reduced models (Table 3), left and right lateral lobe enucleation times were each associated with higher odds of stricture per 10-minute increase, and total lateral lobe enucleation time showed a concordant association. Median lobe enucleation time was not significant, suggesting that stricture risk may relate more closely to the technically demanding lateral phase than to overall enucleation duration. In the prespecified multivariable Firth model (Table 4), total lateral lobe enucleation time remained independently associated with urethral stricture after adjustment for clinically relevant covariates. Model robustness was supported by prespecified sensitivity analyses using alternative specifications, including additional adjustment for median lobe enucleation time and substitution of enucleated tissue weight for prostate volume (Table 5); however, the small number of stricture events limits the precision and stability of the estimates. Together, these findings suggest that step-specific lateral workload captures procedural risk beyond global duration measures and may reflect sustained high-angulation manipulation at the urethral fulcrum. Although en-bloc and two-lobe approaches may improve operative efficiency by reducing repeated lobar transitions [6, 7], current comparative evidence does not establish a reduction in urethral stricture rates [8, 9]. These results therefore support evaluating whether workflows that reduce lateral-phase fulcrum exposure, quantified by phase-specific duration or objective kinematics, can reduce late urethral morbidity.

Preoperative urethral catheterization was more frequent among patients who developed urethral stricture, although the difference was not statistically significant in the unadjusted comparison; the association reached statistical significance only after multivariable adjustment (Tables 1 and 4). This finding should not be interpreted as evidence of a direct causal effect of catheterization. Rather, preoperative catheterization may represent a marker of more severe bladder outlet obstruction or urinary retention, greater prior urethral instrumentation, or pre-existing urethral vulnerability. Because information regarding the duration of preoperative catheterization, repeated catheterization, traumatic insertion, and pre-existing subclinical urethral injury was unavailable, these potential mechanisms could not be distinguished. Moreover, the limited number of stricture events and the wide confidence interval warrant cautious interpretation of this association. Apparent preoperative functional differences observed in the available subset likely reflect catheter-related data unavailability and should not be interpreted as indicating a lower baseline risk of stricture (Table 2).

The association observed is biologically plausible given the mechanical interplay between transurethral instrumentation and urethral anatomy. A randomized trial reporting reduced post-HoLEP urethral stricture with preoperative urethral dilatation supports a role for instrumentation-related frictional and compressive forces in late urethral morbidity [10]. This trial is directionally consistent with our fulcrum-based hypothesis, implying that mitigating urethral entry–related shear and compression (via preoperative dilatation in appropriately selected patients) may reduce downstream stricture formation. Lateral lobe dissection often requires sustained endoscope angulation and lateral force to maintain capsular engagement, and these demands may be accentuated in larger prostates. Prostate volume is a well-established determinant of operative complexity in HoLEP, and larger glands are associated with longer enucleation times [11]. Similarly, even within en-bloc series, gland size remains a preoperative predictor of longer enucleation time, indicating that size-related complexity is not fully eliminated by technique choice [11]. Because lateral lobes frequently represent the dominant adenoma component in larger glands, increasing volume would be expected to preferentially prolong lateral dissection and extend exposure to high-angle lever mechanics at the bulbomembranous junction. Importantly, however, the association between total lateral lobe enucleation time and stricture persisted after adjustment for prostate volume and in sensitivity analyses substituting enucleated tissue weight for volume, suggesting that lateral-phase inefficiency is not merely a surrogate for gland size. Clinically, this implies that patients with similar volumes may experience materially different fulcrum exposure depending on how efficiently the lateral phase is executed, making lateral-phase duration a potentially actionable intraoperative marker to trigger fulcrum-protective strategies.

Motion-tracking data indicate that surgeons—particularly those with less experience—may operate with higher lever angles and more abrupt instrument excursions, potentially increasing stress concentration at the urethral fulcrum near the pelvic floor [12]. In our cohort, strictures clustered immediately distal to the external urethral sphincter, corresponding anatomically to the proximal bulbar urethra at the bulbomembranous junction rather than to the membranous urethra alone. This interpretation is compatible with prior reports describing post-enucleation strictures in close proximity to the membranous urethra [13]. The bulbomembranous junction, as an anatomical transition zone adjacent to the relatively fixed sphincteric segment, may be particularly vulnerable to traction, compression, and shear during high-angle maneuvers. Extreme radial forces generated by scope angulation may further overstretch this region and increase radial stress and dilation at the level of the external urethral sphincter and adjacent bulbomembranous junction [14]. Such angulation-dependent radial loading could plausibly increase local tissue stress at this anatomical transition zone, a pathway that warrants dedicated stricture-focused evaluation. Accordingly, prolonged lateral lobe enucleation time may serve as a clinically accessible proxy for sustained high-angulation manipulation at this urethral pivot point.

As illustrated in Fig. 2, increasing resectoscope angulation can increase loading at the urethral fulcrum by enlarging the effective contact footprint and amplifying compressive and shear forces at the bulbomembranous junction. With coaxial alignment (0°), the functional caliber approximates the nominal sheath size (26 fr). With deflection, the oblique orientation broadens the contact profile, increasing the effective caliber to approximately 30 fr at 30° and potentially to approximately 52 fr at 60° (Fig. 2). Because the urethra is compliant and mobile, these values should not be interpreted as fixed in vivo diameters; rather, the schematic highlights how angulation-dependent contact mechanics may intensify frictional and compressive stress during technically demanding phases of HoLEP.

Fig. 2.

Schematic illustration of angulation-dependent increase in effective sheath caliber at the urethral fulcrum. Conceptual schematic of the angulation-dependent increase in projected sheath caliber at the urethral fulcrum. The upper panels depict a conceptual model of resectoscope positioning during HoLEP, contrasting coaxial alignment (left) with angulated manipulation during lateral dissection (right). The red circle highlights the presumed urethral fulcrum region at the bulbomembranous junction, where contact forces may concentrate when the instrument is deflected. The lower panels illustrate the geometric effect of angulation on the instrument’s projected contact footprint at the fulcrum. Under a simplified projection model (26/cosθ), the projected caliber of a nominal 26-Fr sheath increases from 26 Fr at 0° to approximately 30 Fr at 30° and 52 Fr at 60°. These estimates are theoretical and were not derived from direct in vivo measurements of urethral caliber, tissue deformation, contact pressure, or applied force. The figure is therefore intended solely as a conceptual illustration of how increasing angulation may enlarge the contact footprint and potentially increase local mechanical loading during technically demanding phases of HoLEP

Within this fulcrum-based framework, the impact of resectoscope caliber on urethral stricture remains controversial. In a meta-analysis, Adhoni et al. found that smaller systems (22–24 fr) reduced transient postoperative urinary leakage but did not significantly reduce urethral stricture compared with larger sheaths, suggesting that urethral morbidity may be driven more by the intensity and duration of manipulation than by nominal sheath diameter alone [15]. Comparative series similarly report mixed findings: Ibis et al. [16] observed no difference between 22 fr and 26 fr systems; Sekar et al. [17] reported fewer strictures with a 24 fr versus 26 fr sheath in a post-TURP cohort while noting potential under-ascertainment in retrospective designs; Thai et al. [18] found no difference in urethral complications between 26 fr and 28 fr sheaths in HoLEP; and Günes et al. [19] reported fewer strictures with smaller-diameter resectoscope shafts in TURP, attributing this to reduced urethral friction and mucosal injury. Taken together, the evidence suggests that sheath miniaturization alone may be insufficient to mitigate urethral morbidity when substantial angulation is required, reinforcing the likely importance of maneuver-related mechanical stress and operative efficiency.

The observation that urethral stricture may occur at a similar frequency after TURP and HoLEP, despite the generally smaller range of instrument motion and angulation required during TURP, suggests that angulation is unlikely to be the sole mechanism of urethral injury [4]. Both procedures share several potential sources of urethral trauma, including passage of a relatively large-caliber sheath, insertion-related friction, repetitive axial and rotational instrument movements, sustained compression at fixed urethral contact points, and procedure-duration-dependent mucosal ischemia or microtrauma. During TURP, the cumulative effect of repeated resectoscope advancement, withdrawal, and rotation may therefore produce clinically relevant urethral loading even in the absence of the wider lever angles encountered during enucleation. Accordingly, similar overall stricture rates across the two procedures may arise from different combinations of mechanical exposure: greater angulation and levering during HoLEP versus repeated translational and rotational manipulation during TURP. This interpretation supports a broader instrumentation-related injury model in which the magnitude, duration, direction, and cumulative repetition of urethral loading may all contribute to subsequent stricture formation [4, 17, 19].

Because high deflection enlarges the projected contact footprint at the urethral fulcrum, even smaller sheaths may reach theoretical projected calibers of approximately 48 Fr for a 24-Fr sheath and 44 Fr for a 22-Fr sheath at 60° under the same simplified geometric model, which may help explain the inconsistent reduction in stricture rates reported with miniaturized systems.

These observations have practical implications for stricture mitigation that align with a fulcrum-based mechanism. First, strategies that reduce frictional and compressive stress at urethral entry—such as preoperative urethral dilatation in appropriately selected patients—remain biologically coherent with the proposed pathway and have randomized support for lowering post-HoLEP stricture risk [10]. Second, because our data localize risk to the lateral dissection phase, a logically targeted strategy is to minimize both the magnitude and duration of high-angle maneuvers during lateral enucleation. In practice, this may include workflow refinements that reduce lobar transitions and high-angle re-entry, early creation of adequate working space and capsular exposure to maintain engagement with less torque, and deliberate “resetting” to coaxial alignment whenever feasible. Finally, given evidence that lever angles and abrupt instrument excursions vary with experience, incorporating phase-specific time targets and/or objective kinematic feedback into training and quality improvement may represent a scalable approach to reducing fulcrum loading and downstream urethral morbidity [12].

Direct evidence from lobe-selective HoLEP remains limited because complications are typically reported in aggregate and step-specific timing metrics are rarely available. The findings of Nevo et al. [20] are difficult to interpret mechanistically, as “partial HoLEP” combines median lobe and single lateral lobe procedures without lobe-resolved exposure metrics, and the low event count precludes robust inference. Depaquit et al. [21] reported a selective median lobe HoLEP series with ≥ 1-year follow-up focused primarily on sexual and ejaculatory outcomes; urethral stricture was not a primary endpoint and stricture-specific ascertainment was not emphasized, limiting mechanistic conclusions. Definitive assessment will require systematic stricture ascertainment alongside step-specific operative metrics in standardized cohorts.

Several limitations warrant consideration. This retrospective single-center design limits generalizability and allows residual confounding despite prespecified covariates and bias-reduced regression. The small number of stricture events yields imprecise estimates; therefore, these findings should be considered hypothesis-generating. Restriction to a single high-volume surgeon using a standardized trilobar technique strengthens internal validity but limits external validity and precludes assessment of inter-surgeon variability, learning-curve effects, and center-specific workflows. Total lateral lobe enucleation time is an indirect proxy for angulation and fulcrum-related urethral loading and may also capture unmeasured anatomical or intraoperative difficulty. Redo procedures were excluded because any prior prostate surgery was an exclusion criterion, while gland size was addressed by adjustment for preoperative prostate volume and by a sensitivity analysis in which enucleated tissue weight was substituted for prostate volume. Enucleation efficiency was not additionally included in the multivariable model because it is derived from enucleation time and tissue weight, which are closely related to the primary exposure and existing model variables, and its inclusion could introduce collinearity or overadjustment in a model based on only eight events. Nevertheless, residual confounding by adenoma configuration, capsular adherence, tissue characteristics, or other unmeasured sources of technical difficulty cannot be excluded. In particular, specific prostate geometries—including a large anteroposterior diameter, marked transverse enlargement of the lateral lobes, or a steep bladder neck angle—may require greater resectoscope deflection, levering, or torque during lateral enucleation and may therefore influence urethral fulcrum exposure independently of overall prostate volume. These anatomical characteristics were not systematically measured in the present retrospective cohort and should be evaluated in future studies using standardized preoperative imaging measurements. Objective measures of lever angle, sheath kinematics, irrigation dynamics, or applied force were unavailable, and future studies combining preoperative anatomical measurements with motion tracking or instrumented assessment are needed to test the proposed mechanism directly. Finally, because follow-up was censored at stricture diagnosis, between-group differences in observed follow-up should be interpreted cautiously when using logistic regression rather than a time-to-event framework.

Despite these limitations, total lateral lobe enucleation time remained independently associated with postoperative urethral stricture, suggesting that lateral dissection workload may capture procedural risk beyond global duration measures. Although directionally consistent with previous reports implicating instrumentation-related mechanics and operative efficiency, these findings remain hypothesis-generating because published cohorts are heterogeneous and rarely include step-specific exposure data [12, 15–21]. They support prospective evaluation of workflow optimization, angulation-sparing maneuvers, and urethral fulcrum-protective strategies.

Conclusions

In this technique-standardized trilobar HoLEP cohort, longer total lateral lobe enucleation time was independently associated with postoperative urethral stricture. These findings support a fulcrum-related instrumentation-injury hypothesis but should be considered hypothesis-generating and require confirmation in larger multicenter cohorts incorporating objective measures of instrument angulation and applied force.

Abbreviations

BPH

Benign prostatic hyperplasia

CI

Confidence interval

fr

French (gauge)

HoLEP

Holmium laser enucleation of the prostate

IPSS

International Prostate Symptom Score

IQR

Interquartile range

OR

Odds ratio

PSA

Prostate–specific antigen

PVR

Postvoid residual urine

Qaverage

Average flow rate

Qmax

Maximum flow rate

SPSS

Statistical Package for the Social Sciences

TURP

Transurethral resection of the prostate

YAG

Yttrium aluminium garnet

Authors’ contributions

YK: Research conception and design; statistical analysis; data analysis and interpretation; drafting of the manuscript; critical revision of the manuscript; supervision; approval of the final manuscript. TBA: Data acquisition; critical revision of the manuscript; supervision; approval of the final manuscript.

Funding

No financial support or grants were received.

Data availability

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study was approved by the institutional ethics committee (decision no. 2025/010.99/22/29; November 26, 2025). Informed consent was waived because of the retrospective design and use of de-identified data. The study was conducted in accordance with institutional policies and the principles of the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.