Abstract
This study was performed to investigate the learning curve of transurethral enucleation with bipolar energy (TUEB) for benign prostatic hyperplasia. The study involved 494 consecutive patients who underwent TUEB for benign prostatic hyperplasia from August 2018 to March 2022 by one surgeon (SJJ, Seoul National University Bundang Hospital, Seongnam, Korea). The patients were followed up at 1 week, 1 month, 3 months, and 6 months postoperatively. To evaluate the learning curve of TUEB, perioperative parameters including the enucleation ratio (enucleated tissue weight/transitional zone volume), TUEB efficiency (enucleated tissue weight/operation time), and enucleation efficiency (enucleated tissue weight/enucleation time) were analyzed. Functional outcomes and postoperative complications were also assessed, including the International Prostate Symptom Score (IPSS), IPSS quality-of-life (QoL) score, and uroflowmetry outcomes. The patients’ median age was 72 (interquartile range [IQR]: 66–78) years, and the estimated prostate volume and transitional zone volume were 63.0 (IQR: 46.0–90.6) ml and 37.1 (IQR: 24.0–60.0) ml, respectively. The enucleation ratio, TUEB efficiency, and enucleation efficiency were 0.60 (IQR: 0.46–0.54) g ml−1, 0.33 (IQR: 0.22–0.46) g min−1, and 0.50 (IQR: 0.35–0.72) g min−1, respectively, plateauing after 70 cases. The functional outcomes, including total IPSS, IPSS QoL score, and uroflowmetry outcomes, significantly improved at 6 months after TUEB (all P < 0.05), but without significant differences over the learning curve. Sixty-five (13.2%) patients developed complications after TUEB, 21.5% of whom experienced major complications (Clavien–Dindo grade ≥3). The rate of major complications declined as the number of TUEB cases increased (P = 0.013). Our results suggest that the efficiency of TUEB stabilized within 70 procedures.
Keywords: benign prostate hyperplasia, learning curve, perioperative efficiency, prostate, transurethral enucleation with bipolar energy
INTRODUCTION
Transurethral resection of the prostate (TURP) is recognized as the gold standard surgical treatment option for symptomatic benign prostatic hyperplasia (BPH). However, the limitation of the ideal prostate size for TURP and the potential risk of morbidities, such as TURP syndrome and bleeding, have motivated clinicians to adopt novel transurethral treatment techniques instead of conventional TURP. Such techniques include transurethral enucleation, water vapor thermal therapy, temporary implantation of a nitinol device, and Aquablation®.1 Currently, transurethral enucleation along with TURP is considered the surgical treatment of choice.2
In 1989, the first reported attempt of transurethral endoscopic enucleation was performed by Hiraoka and Akimoto3 but went unnoticed for some time. The concept of transurethral enucleation began to attract interest in clinical practice again in 1998, when Gilling et al.4 reported the advantage of holmium laser enucleation of the prostate (HoLEP) in combination with mechanical morcellation. Currently, HoLEP is well recognized as an appropriate alternative to conventional TURP for medium-sized prostates. Nevertheless, HoLEP has several limitations, such as the high costs of laser devices and morcellators, that have prevented its widespread acceptance, especially in underdeveloped countries.5 By contrast, transurethral enucleation with bipolar energy (TUEB) requires only a specialized spatula loop in addition to conventional TURP in a saline system.6
Li et al.7 reviewed previous studies which have compared TUEB with HoLEP in terms of aspects other than cost-effectiveness, concluding that HoLEP was associated with a lower operative time, shorter catheterization time, lower bladder irrigation time, and higher enucleation weight than TUEB without notable differences in functional outcomes or complication rates. When comparing TUEB and HoLEP with regard to learning curve, a prospective study involving 90 participants suggested that enucleation using electric energy requires more time to acquire sufficient skill than does laser enucleation.8 In addition, a systemic review reported that TUEB requires approximately 40 cases to 50 cases to reach the plateau, whereas the learning curve of HoLEP is approximately 30 cases to 40 cases.9
However, very few studies have compared the learning curves of TUEB and HoLEP.10,11,12 We aimed to evaluate the learning curve and efficiency of TUEB based on a single-surgeon experience.
PATIENTS AND METHODS
Ethics statement
The Institutional Review Board (IRB) of Seoul National University Bundang Hospital (Seongnam, Korea) approved this study (Approval No. B-2210-789-105). The requirement for written informed consent was waived because of the retrospective nature of our study. All methods were conducted in accordance with relevant guidelines and regulations, including the ethical standards of the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
Study population
We retrospectively analyzed the medical records of 517 patients who underwent TUEB for treatment of BPH with lower urinary tract symptoms from August 2018 to March 2022 at our institution (Seoul National University Bundang Hospital). Of the 517 patients, those with a previous diagnosis of prostate cancer (n = 5), previous diagnosis of neurogenic bladder (n = 3), and history of surgery for BPH (n = 15) were excluded, leaving 494 patients for analysis. In the final cohort, no patients had urethral stricture, a history of bladder cancer, or concurrent cystolitholapaxy for bladder stones.
Operative procedure and technique
All TUEB procedures were performed by a single urologist (SJJ) who had more than 10 years of experience performing TURP and was relatively inexperienced with the enucleation technique.
The TUEB technique in the present study was based on a previously described technique,13 with several modifications to incorporate en bloc enucleation with early apical release. Prostate enucleation was performed using an Olympus transurethral resection in saline bipolar energy resection system (Olympus Medical Systems Corp., Tokyo, Japan), with both a standard tungsten wire loop and PLASMA enucleation electrode (Olympus Medical Systems Corp.) containing a round spatula in the front (Figure 1a). The settings employed for the enucleation procedure were 200 W and 120 W for cutting and coagulation, respectively. The entire enucleation procedure was performed as follows. First, a groove was created from the 5- to 7-o’clock position of the prostatic urethra at the level of the verumontanum, which is considered the prostatic apex, using a standard tungsten loop. This was followed by circumferential expansion of the groove to both lateral lobes (Figure 2a). Second, the operator repeatedly pushed the spatula against the prostatic adenoma toward the bladder neck, which allowed the prostatic adenoma to be gently torn away from the capsule (Figure 2b–2d). The remaining adenoma tissue at the 12-o’clock position was resected (Figure 2e and 2f). When any active bleeding was observed, electrocauterization using a standard wire loop was performed at the operator’s discretion. After enucleation was completed with the prostatic adenoma pushed into the bladder, morcellation was performed using a DrillCut™ morcellator (Karl Storz Inc., Tuttlingen, Germany) with an oscillating toothed blade (Figure 1b). A rigid nephroscope with a 5-mm working channel was used to introduce the morcellator using a dual irrigation system. The morcellation speed was set at 3 Hz and 1600 rpm. After surgery, all patients underwent insertion of a 22-Fr three-way Foley catheter with continuous irrigation. The flow of irrigation was gradually reduced, and the operator determined the time points at which continuous irrigation was stopped and the catheter was removed. In general, irrigation was stopped the next morning, and the Foley catheter was removed after confirming the cessation of hematuria on postoperative day 2 or 3. When adequate self-voiding was confirmed after removal of the Foley catheter, the patients were discharged. Patients in whom slight hematuria persisted until postoperative day 3 were discharged with the Foley catheter, which was removed 1 week later at an outpatient clinic.
Figure 1.
Transurethral enucleation of the prostate with bipolar energy equipment in Seoul National University Bundang Hospital. (a) PLASMA enucleation electrode with spatula for prostate enucleation. (b) DrillCut™ morcellator system for prostate morcellation.
Figure 2.
Overall procedure of transurethral enucleation with bipolar energy (TUEB) using a spatula loop. (a) Circumferential marking and incision at the apical urethral mucosa surface (start at 5- and 7- o’clock positions and proceed upward). (b) Upward enucleation of the left and right lobes from just lateral to the verumontanum (laterally and upwardly) using TUEB spatula loop. (c) Enucleation of both lateral lobes using TUEB spatula loop. (d) Enucleation of the anterior side of lateral lobes and anterior lobe (en bloc procedure). (e) Bladder neck mucosa incision. (f) Detachment of the most distal mucosal stalk.
Surgical outcomes of TUEB and follow-up
Every patient was followed up at an outpatient clinic within 1 week after surgery. After outpatient follow-up at 1 month postoperatively, the patients were recommended to visit the outpatient clinic at 3 months to 6 months and then every 6 months or 12 months. Each patient underwent routine baseline assessment before TUEB, which included the following assessments: serum prostate-specific antigen (PSA), transrectal ultrasonography (TRUS), International Prostate Symptom Score (IPSS), IPSS quality-of-life (QoL) score, and uroflowmetry. For patients who did not undergo prostate biopsy preoperatively despite an increased serum PSA level or the presence of a palpable nodule or induration on digital rectal examination, intraoperative TRUS-guided biopsies were also performed.
The perioperative outcomes were the weight of the enucleated prostatic adenoma, total operation time, enucleation time, morcellation time, pathologic results, duration of postoperative Foley catheterization, and length of hospital stay. The parameters used to evaluate the learning curve were the enucleation ratio, TUEB efficiency, enucleation efficiency, and morcellation efficiency, as reported in previous studies.10,11,12 The enucleation ratio was defined as the ratio of the enucleated weight of the prostate (g) per transitional zone volume (ml) on TRUS. The TUEB theoretical efficiency was calculated as the ratio of the transitional zone volume (ml) per total operative time (min), and the TUEB efficiency was defined as the ratio of the enucleated weight of the prostate (g) per total operative time (min). We also calculated the enucleation efficiency and morcellation efficiency as the ratio of the enucleation weight per enucleation time and morcellation time, respectively.
Complications of TUEB
Intraoperative complications were defined as any complications occurring during TUEB, including capsular perforation or bladder injury. Postoperative complications were subgrouped into minor and major complications according to the Clavien–Dindo classification.14 Major complications were defined as Clavien–Dindo grade ≥3. Early postoperative complications were defined as complications occurring within 1 month after TUEB.
Statistical analyses
All statistical analyses were performed using IBM SPSS Statistics version 22.0 (IBM Corp., Armonk, NY, USA). Normality was determined with the Kolmogorov–Smirnov test. Categorical variables were compared using the Chi-square test or Fisher’s exact test, whereas continuous variables were evaluated using the Mann–Whitney U test. All reported P-values are two-sided, and statistical significance was considered at P < 0.05. For post hoc analyses among the three groups, statistical significance was considered when the Bonferroni-adjusted P-value was <0.017 (0.05/3).
RESULTS
The patients’ baseline characteristics and perioperative outcomes are shown in Table 1. The median age of the 494 patients was 72 (interquartile range [IQR]: 66–78) years, and the median estimated prostate volume and median estimated transitional zone volume on preoperative TRUS were 63.0 (IQR: 46.0–90.6) ml and 37.1 (IQR: 24.0–60.0) ml, respectively. The median baseline serum PSA level was 3.96 (IQR: 1.85–8.10) ng ml−1. Among all TUEB procedures in our study, the median operation time was 70.0 (IQR: 55.0–90.0) min, the median enucleated prostate weight was 22.0 (IQR: 14.0–37.0) g, and the median enucleation time was 45.0 (IQR: 35.0–60.0) min. As the primary variables to evaluate the learning curve, the median enucleation ratio, TUEB efficiency, enucleation efficiency, and morcellation efficiency were 0.60 (IQR: 0.46–0.54) g ml−1, 0.33 (IQR: 0.22–0.46) g min−1, 0.50 (IQR: 0.35–0.72) g min−1, and 1.16 (IQR: 0.70–1.62) g min−1, respectively. The median hospital stay was 3 days, and the median postoperative catheterization duration was 4 days.
Table 1.
Baseline clinical and perioperative characteristics of patients who underwent transurethral enucleation with bipolar energy (n=494)
| Parameter | Value |
|---|---|
| Age (year), median (IQR) | 72 (66–78) |
| BMI (kg m−2), median (IQR) | 24.42 (22.57–26.45) |
| Hypertension, n (%) | 262 (53.0) |
| Diabetes mellitus, n (%) | 120 (24.3) |
| Preoperative PSA (ng ml−1), median (IQR) | 3.96 (1.85–8.10) |
| History of prior acute urinary retention, n (%) | 151 (30.6) |
| History of prior alpha-blocker agent, n (%) | 424 (85.8) |
| History of prior anticholinergics, n (%) | 130 (26.3) |
| History of prior anticoagulant agent, n (%) | 155 (31.4) |
| Evaluated prostate volume on TRUS (ml), median (IQR) | 63.0 (46.0–90.6) |
| Evaluated transitional zone volume on TRUS (ml), median (IQR) | 37.1 (24.0–60.0) |
| Transitional zone volume/prostate volume (%), median (IQR) | 59.5 (49.5–69.2) |
| Operation time (min), median (IQR) | 70.0 (55.0–90.0) |
| Enucleation time (min), median (IQR) | 45.0 (35.0–60.0) |
| Morcellation time (min), median (IQR) | 20.0 (15.0–31.3) |
| Enucleation ratio (g ml−1), median (IQR) | 0.60 (0.46–0.54) |
| TUEB theoretical efficiency (ml min−1), median (IQR) | 0.55 (0.40–0.74) |
| Enucleation weight (g), median (IQR) | 22.0 (14.0–37.0) |
| TUEB efficiency (g min−1), median (IQR) | 0.33 (0.22–0.46) |
| Enucleation efficiency (g min−1), median (IQR) | 0.50 (0.35–0.72) |
| Morcellation efficiency (g min−1), median (IQR) | 1.16 (0.70–1.62) |
| Catheterization duration (day), median (IQR) | 4 (3–5) |
| Hospital stay (day), median (IQR) | 3 (2–4) |
IQR: interquartile range; BMI: body mass index; PSA: prostate-specific antigen; TRUS: transrectal ultrasonography; TUEB: transurethral enucleation with bipolar energy
We summarize the changes in the enucleation ratio (Figure 3a), TUEB theoretical efficiency (Figure 3b), TUEB efficiency (Figure 3c), and enucleation efficiency (Figure 3d) in the order of consecutive TUEB cases. Based on the 20-case average method (red lines), the enucleation ratio, TUEB efficiency, and enucleation efficiency showed a tendency to reach a plateau after approximately 70–80 consecutive cases. The perioperative parameters were compared among the three groups (Table 2): group 1 (initial 70 patients), group 2 (second 70 patients), and group 3 (remaining patients). In the post hoc analysis among the three groups, the median enucleation ratio (group 1 vs group 2: 0.48 g ml−1 vs 0.61 g ml−1, Bonferroni-adjusted P = 0.011), TUEB efficiency (group 1 vs group 2: 0.27 g min−1 vs 0.33 g min−1, Bonferroni-adjusted P = 0.003), and enucleation efficiency (group 1 vs group 2: 0.38 g min−1 vs 0.50 g min−1, Bonferroni-adjusted P = 0.001) improved substantially compared to the initial 70 consecutive cases. However, there were no significant differences between the second 70 cases and the remaining cases (all Bonferroni-adjusted P > 0.017). No significant differences were found in the median estimated prostate volume, transitional zone volume, operation time, enucleation time, morcellation time, TUEB theoretical efficiency, or morcellation efficiency (all Bonferroni-adjusted P > 0.017).
Figure 3.
Changes in perioperative parameters related to the learning curve in order of the number of consecutive transurethral enucleation of the prostate with bipolar energy (TUEB) cases. The moving average method was used to determine changes in TUEB efficiency. A 20-case moving average was used (red line). (a) Enucleation ratio. (b) TUEB theoretical efficiency. (c) TUEB efficiency. (d) Enucleation efficiency.
Table 2.
Comparison of baseline and postoperative functional outcomes after transurethral enucleation with bipolar energy among three consecutive groups
| Parameter | G1 (initial 70 cases) | G2 (second 70 cases) | G3 (the remainders) | P |
|---|---|---|---|---|
| Estimated prostate volume (ml), median (IQR) | 63.5 (48.4–83.3) | 65.5 (51.8–97.5) | 62.9 (43.9–94.0) | G1 vs G2: 0.317 G1 vs G3: 0.890 G2 vs G3: 0.211 |
| Estimated transitional zone volume (ml), median (IQR) | 35.8 (27.0–51.7) | 37.0 (26.0–57.9) | 38.0 (23.0–60.7) | G1 vs G2: 0.592 G1 vs G3: 0.698 G2 vs G3: 0.211 |
| Transitional zone volume/prostate volume (%), median (IQR) | 58.7 (51.3–66.4) | 58.4 (46.2–66.7) | 60.0 (48.8–70.0) | G1 vs G2: 0.475 G1 vs G3: 0.637 G2 vs G3: 0.205 |
| Operation time (min), median (IQR) | 70.0 (55.0–90.0) | 72.5 (50.0–90.0) | 70.0 (55.0–86.3) | G1 vs G2: 0.668 G1 vs G3: 0.524 G2 vs G3: 0.990 |
| Enucleation time (min), median (IQR) | 47.5 (40.0–60.0) | 50.0 (35.0–55.0) | 45.0 (35.0–60.0) | G1 vs G2: 0.212 G1 vs G3: 0.062 G2 vs G3: 0.585 |
| Morcellation time (min), median (IQR) | 20.0 (15.0–30.0) | 25.0 (15.0–30.0) | 25.0 (15.0–35.0) | G1 vs G2: 0.361 G1 vs G3: 0.253 G2 vs G3: 0.914 |
| Enucleation weight (g), median (IQR) | 20.0 (12.0–26.3) | 24.0 (15.0–35.5) | 23.0 (13.8–39.0) | G1 vs G2: 0.043 G1 vs G3: 0.026 G2 vs G3: 0.969 |
| Enucleation ratio (g ml−1), median (IQR) | 0.48 (0.37–0.48) | 0.61 (0.45–0.80) | 0.62 (0.50–0.76) | G1 vs G2: 0.011* G1 vs G3: <0.001* G2 vs G3: 0.635 |
| TUEB theoretical efficiency (ml min−1), median (IQR) | 0.51 (0.40–0.66) | 0.54 (0.46–0.74) | 0.56 (0.39–0.77) | G1 vs G2: 0.191 G1 vs G3: 0.342 G2 vs G3: 0.763 |
| TUEB efficiency (g min−1), median (IQR) | 0.27 (0.18–0.34) | 0.33 (0.23–0.42) | 0.34 (0.23–0.49) | G1 vs G2: 0.003* G1 vs G3: <0.001* G2 vs G3: 0.722 |
| Enucleation efficiency (g min−1), median (IQR) | 0.38 (0.28–0.49) | 0.50 (0.36–0.70) | 0.53 (0.38–0.74) | G1 vs G2: 0.001* G1 vs G3: <0.001* G2 vs G3: 0.424 |
| Morcellation efficiency (g min−1), median (IQR) | 1.00 (0.69–1.40) | 1.11 (0.79–1.36) | 1.20 (0.66–1.80) | G1 vs G2: 0.237 G1 vs G3: 0.020 G2 vs G3: 0.180 |
*P<0.017. In post hoc analysis, the statistical significance was considered when Bonferroni-corrected P<0.017. G1: group 1 of initial 70 cases; G2: group 2 of second 70 cases; G3: group 3 of the remainders; IQR: interquartile range; TUEB: transurethral enucleation with bipolar energy
Intraoperative, early postoperative (<30 days), and late postoperative (≥30 days) complications after TUEB are listed in Table 3. In total, 72 (14.6%) patients developed intraoperative complications during TUEB, without significant differences among the three groups (8.6%, 22.9%, and 14.1%; P = 0.051). All 11 patients who developed bladder injury during TURB recovered by conservative management with an indwelling Foley catheter and did not require additional bladder repair. By contrast, the incidence of additional TURP decreased as the number of TUEB cases increased (34.3%, 17.1%, and 3.1%; P < 0.001). A total of 65 (13.2%) patients developed postoperative complications, with no significant differences among the three groups (17.1%, 14.1%, and 12.1%; P = 0.505), whereas the incidence of major complications (Clavien–Dindo grade ≥3) decreased as the number of TUEB cases increased (50.0%, 30.0%, and 11.6%; P = 0.013). In addition, 43 (8.7%) patients developed early complications within 1 month after TUEB. Of the 32 patients who experienced gross hematuria, 10 (31.3%) underwent transurethral coagulation under anesthesia. No significant difference was found in the ratio of patients with gross hematuria who recovered with conservative management (Clavien–Dindo grade <3) among the three groups (2.9%, 2.9%, and 5.1%; P = 0.610), whereas the ratio of patients with hematuria requiring surgical treatment (Clavien–Dindo grade ≥3) decreased as the number of TUEB cases increased (5.7%, 4.3%, and 0.8%; P = 0.011). Furthermore, 5 (1.0%) patients developed acute urinary retention after removal of the Foley catheter after TUEB, necessitating recatheterization for heterization for ≤1 week, and 2 patients developed acute epididymitis postoperatively and were prescribed oral antibiotics.
Table 3.
Comparison of intraoperative complications and early and late postoperative complications after transurethral enucleation with bipolar energy among three consecutive groups
| Parameter | Group 1 (initial 70 cases) | Group 2 (second 70 cases) | Group 3 (the remainders) | P |
|---|---|---|---|---|
| Overall intraoperative complication, n (%) | 6 (8.6) | 16 (22.9) | 50 (14.1) | 0.051 |
| Bladder injury | 0 (0) | 4 (5.7) | 7 (2.0) | 0.055 |
| Prostate capsular perforation | 6 (8.6) | 14 (20.0) | 44 (12.4) | 0.109 |
| Intraoperative additional TURP, n (%) | 24 (34.3) | 12 (17.1) | 11 (3.1) | <0.001* |
| Overall postoperative complication, n (%) | 12 (17.1) | 10 (14.1) | 43 (12.1) | 0.505 |
| Minor (Clavien–Dindo grade <3) | 6 (50.0) | 7 (70.0) | 38 (88.4) | 0.013* |
| Major (Clavien–Dindo grade ≥3) | 6 (50.0) | 3 (30.0) | 5 (11.6) | |
| Early complication (< postoperative 30 days), n (%) | 8 (11.4) | 8 (11.4) | 27 (7.6) | 0.402 |
| Minor (Clavien–Dindo grade <3) early complication (postoperative gross hematuria), n (%) | 2 (2.9) | 2 (2.9) | 18 (5.1) | 0.610 |
| Acute epididymitis | 0 (0) | 1 (1.4) | 1 (0.3) | 0.487 |
| Acute urinary retention | 1 (1.4) | 2 (2.9) | 2 (0.6) | 0.141 |
| LUTS | 1 (1.4) | 0 (0) | 3 (0.8) | 0.738 |
| Major (Clavien–Dindo grade ≥3) early complication (postoperative gross hematuria), n (%) | 4 (5.7) | 3 (4.3) | 3 (0.8) | 0.011* |
| Late complications (≥ postoperative 30 days), n (%) | 4 (5.7) | 3 (4.3) | 16 (4.5) | 0.941 |
| Minor (Clavien–Dindo grade <3) late complication (SUI at 3–6 months after TUEB), n (%) | 1 (1.4) | 1 (1.4) | 14 (4.0) | 0.502 |
| Major (Clavien–Dindo grade ≥3) late complication, n (%) | ||||
| Urethral stricture | 1 (1.4) | 1 (1.4) | 1 (0.3) | 0.195 |
| Bladder neck contracture | 1 (1.4) | 0 (0) | 0 (0) | 0.283 |
| reTUR for residual prostatic adenoma | 0 (0) | 1 (1.4) | 0 (0) | 0.283 |
*P<0.017. TURP: transurethral resection of the prostate; LUTS: lower urinary tract symptoms; SUI: stress urinary incontinence; TUEB: transurethral enucleation with bipolar energy; reTUR: repeated transurethral resection
Of the 23 (4.7%) patients with late complications, 1 patient required a reoperation because of a residual adenoma. Among the three patients who developed urethral stricture, one patient was treated by internal urethrotomy under direct vision 4 months after TUEB, and another patient underwent suprapubic catheterization. The last patient was observed without surgical management. For one patient with bladder neck contracture, transurethral incision of the bladder neck was performed 9 months postoperatively. Sixteen patients developed stress urinary incontinence at 3 months and 6 months after TUEB.
The parameters of urinary function after TUEB are shown in Supplementary Table 1 and 2. In general, the maximal urinary flow rate, postvoid residual volume, total IPSS total, and IPSS QoL score at 1 month, 3 months, and 6 months after TUEB improved significantly from baseline (all P < 0.001). The postoperative median maximal urinary flow rate peaked at 1 month after TUEB (baseline vs postoperative 1 month: 9.0 ml s−1 vs 17.0 ml s−1; P < 0.001) but declined thereafter, reaching a plateau (postoperative 1 month vs 3 months: 17.0 ml s−1 vs 15.0 ml s−1; P = 0.133; postoperative 1 month vs 6 months: 17.0 ml s−1 vs 13.0 ml s−1; P = 0.334; and postoperative 3 months vs 6 months: 15.0 ml s−1 vs 13.0 ml s−1; P = 0.203). By contrast, the postvoid residual volume, total IPSS, and IPSS QoL score improved continuously after TUEB (Supplementary Table 1). When comparing the baseline and postoperative urinary functional outcomes over time among the three groups, there were no significant differences in functional outcomes according to the number of consecutive TUEB cases (all Bonferroni-adjusted P > 0.017; Supplementary Table 2).
Supplementary Table 1.
Comparison of functional outcomes over time after transurethral enucleation with bipolar energy
| Parameters | Baseline | At 1 month postoperatively | At 3 months postoperatively | At 6 months postoperatively | P |
|---|---|---|---|---|---|
| Qmax (ml/s), median (IQR) | 9.0 (6.0–12.0) | 17.0 (12.0–24.0) | 15.0 (8.0–21.0) | 13.0 (9.8–26.3) | Baseline vs 1 mon: <0.001 Baseline vs 3 mon: <0.001 Baseline vs 6 mon: <0.001 1 mon vs 3 mon: 0.133 1 mon vs 6 mon: 0.334 3 mon vs 6 mon: 0.203 |
| PVR (ml), median (IQR) | 76.0 (30.0–126.3) | 30.0 (15.0–50.0) | 20.0 (<0.1–34.5) | 17.5 (<0.1–32.3) | Baseline vs 1 mon: <0.001 Baseline vs 3 mon: <0.001 Baseline vs 6 mon: <0.001 1 mon vs 3 mon: <0.001 1 mon vs 6 mon: <0.001 3 mon vs 6 mon: 0.091 |
| IPSS total score, median (IQR) | 20 (14–26) | 12 (6–19) | 9 (4–16) | 9 (4–14) | Baseline vs 1 mon: <0.001 Baseline vs 3 mon: <0.001 Baseline vs 6 mon: <0.001 1 mon vs 3 mon: 0.015 1 mon vs 6 mon: 0.010 3 mon vs 6 mon: <0.001 |
| IPSS-QoLs, median (IQR) | 4 (4–5) | 3 (2–4) | 2 (1–4) | 2 (1–3) | Baseline vs 1 mon: <0.001 Baseline vs 3 mon: <0.001 Baseline vs 6 mon: <0.001 1 mon vs 3 mon: 0.001 1 mon vs 6 mon: <0.001 3 mon vs 6 mon: 0.022 |
Data are presented as median (IQR). IQR: interquartile range; 1 mon: at 1 month postoperatively; 3 mon: at 3 months postoperatively; 6 mon: at 6 months postoperatively; Qmax: maximum flow rate; PVR: postvoid residual urine volume; IPSS: International Prostate Symptom Score; QoLs: quality of life score
Supplementary Table 2.
Comparison of baseline and postoperative functional outcomes after transurethral enucleation with bipolar energy among three consecutive groups
| Variable | G1 (1st 70 cases) | G2 (2nd 70 cases) | G3 (reminders) | P |
|---|---|---|---|---|
| Baseline Qmax (ml/s), median (IQR) | 8.0 (6.0–10.0) | 8.0 (6.0–11.3) | 9.0 (6.0–13.0) | G1 vs G2: 0.917 G1 vs G3: 0.142 G2 vs G3: 0.159 |
| Baseline PVR (ml), median (IQR) | 70.0 (37.0–145.0) | 95.0 (39.0–156.0) | 73.0 (30.0–120.0) | G1 vs G2: 0.475 G1 vs G3: 0.558 G2 vs G3: 0.117 |
| Baseline IPSS total score, median (IQR) | 20 (8–29) | 21 (13–26) | 20 (14–26) | G1 vs G2: 0.418 G1 vs G3: 0.338 G2 vs G3: 0.766 |
| Baseline IPSS-QoLs, median (IQR) | 4 (3–5) | 5 (4–5) | 4 (4–5) | G1 vs G2: 0.062 G1 vs G3: 0.097 G2 vs G3: 0.216 |
| Qmax (ml/s) on postoperatively 1 month, median (IQR) | 15.0 (11.3–23.0) | 16.0 (10.3–23.0) | 17.0 (12.0–24.0) | G1 vs G2: 0.607 G1 vs G3: 0.392 G2 vs G3: 0.876 |
| PVR (mL) on postoperatively 1 month, median (IQR) | 30.0 (6.0–57.3) | 37.5 (20.0–58.8) | 30.0 (11.0–50.0) | G1 vs G2: 0.187 G1 vs G3: 0.821 G2 vs G3: 0.122 |
| IPSS total score on postoperatively 1 month, median (IQR) | 10 (5–18) | 12 (6–19) | 12 (7–19) | G1 vs G2: 0.678 G1 vs G3: 0.362 G2 vs G3: 0.860 |
| IPSS-QoLs on postoperatively 1 month, median (IQR) | 3 (2–4) | 4 (3–5) | 4 (2–4) | G1 vs G2: 0.102 G1 vs G3: 0.314 G2 vs G3: 0.235 |
| Qmax (ml/s) on postoperatively 3 months, median (IQR) | 14.0 (8.0–18.0) | 17.0 (12.0–23.0) | 15.0 (9.0–21.0) | G1 vs G2: 0.094 G1 vs G3: 0.587 G2 vs G3: 0.165 |
| PVR (ml) on postoperatively 3 months, median (IQR) | 30.0 (8.0–50.0) | 19.0 (9.0–40.0) | 20.0 (0.0–39.5) | G1 vs G2: 0.318 G1 vs G3: 0.097 G2 vs G3: 0.574 |
| IPSS total score on postoperatively 3 months, median (IQR) | 5 (3–11) | 11 (4–22) | 9 (5–16) | G1 vs G2: 0.068 G1 vs G3: 0.007* G2 vs G3: 0.668 |
| IPSS-QoLs on postoperatively 3 months, median (IQR) | 2 (1–2) | 4 (1–4) | 2 (1–4) | G1 vs G2: 0.026 G1 vs G3: 0.039 G2 vs G3: 0.177 |
| Qmax (ml/s) on postoperatively 6 months, median (IQR) | 15.0 (8.5–23.5) | 18.0 (13.0–27.0) | 13.0 (9.0–22.0) | G1 vs G2: 0.247 G1 vs G3: 0.898 G2 vs G3: 0.086 |
| PVR (ml) on postoperatively 6 months, median (IQR) | 20.0 (6.3–45.0) | 15.0 (0.0–35.0) | 17.5 (0.0–31.5) | G1 vs G2: 0.365 G1 vs G3: 0.412 G2 vs G3: 0.762 |
| IPSS total score on postoperatively 6 months, median (IQR) | 6 (4–10) | 10 (5–14) | 9 (5–17) | G1 vs G2: 0.176 G1 vs G3: 0.235 G2 vs G3: 0.974 |
| IPSS-QoLs on postoperatively 6 months, median (IQR) | 2 (1–3) | 3 (2–4) | 2 (1–4) | G1 vs G2: 0.093 G1 vs G3: 0.274 G2 vs G3: 0.301 |
*P<0.017. In post hoc analysis, the statistical significance was considered when Bonferroni-corrected P<0.017. Data are presented as median (IQR). G1: group 1, G2: group 2, G3: group 3, IQR: interquartile range, Qmax: maximum flow rate, PVR: postvoid residual urine volume, IPSS: International Prostate Symptom Score, QoLs: quality of life score
DISCUSSION
Transurethral enucleation techniques including HoLEP and TUEB have been accepted as good alternatives to conventional TURP,2 and several studies have compared HoLEP and TUEB. In general, no significant differences in functional outcomes or complications have been found between HoLEP and TUEB, although HoLEP presents more advantages as shown by perioperative parameters.7,15,16 Multiple studies have shown that the learning curve of HoLEP is 30 to 40 cases.9 To our knowledge, however, few studies have explored the learning curve of TUEB.10,11,12 The present study is one of the largest retrospective studies to evaluate the surgical outcomes and learning curve of TUEB.
In the present study, subjective urinary symptoms, QoL, uroflowmetry parameters, and the total serum PSA level improved significantly after TUEB. The median hospital stay was 4 days, and the median postoperative catheterization duration was 3 days. These results are consistent with those of previous studies of TUEB.10,11,12,15
Our study showed that 70 TUEB cases were required to reach a plateau status. This is a relatively high number compared with the findings of previous studies.10,11,12 Furthermore, the median enucleation ratio, TUEB efficiency, and enucleation efficiency at the plateau stage in our study were 0.60 g ml−1, 0.33 g min−1, and 0.50 g min−1, respectively, which were relatively inferior compared with those in previous studies.6,11,12,16 These results can be partially explained by the lack of a structured mentoring system at our institution. Although our operator had more than 10 years of experience in TURP, a proficient mentor who could supplement the operator’s relative lack of experience in TUEB was not available. Several studies have stressed the importance of proper mentoring systems to reduce the learning curve of HoLEP. Elzayat and Elhilali17 reported that 20–30 consecutive cases were required for operators to become skilled in HoLEP with proper mentoring, while about 50 cases were required without mentoring. Westhofen et al.18 also suggested that a structured training program could help overcome the steep learning curve of HoLEP. Although no previous study has compared the learning curve of TUEB with and without mentoring systems, Feng et al.11 suggested that the learning curve under a mentoring system was 40 cases.
In the present study, 72 (14.6%) and 65 (13.2%) patients developed intraoperative and postoperative complications, respectively. There were no significant differences in the incidence of these complications according to the learning curve, but the incidence of major complications decreased as the number of TUEB cases increased. In previous studies, the overall complication rate ranged from 6.9% to 38.7%,13,19,20,21,22,23 which is consistent with our results.
The most frequent early complication in this study was gross hematuria, which was observed in 33 patients. No significant difference was found in the rate of gross hematuria over time; however, the rate of gross hematuria requiring surgical management tended to decrease over time. The overall incidence of postoperative gross hematuria requiring surgical intervention in our study (2.0%) was comparable to that in previous studies (1.5%–2.5%).11,24 In addition, the incidence of postoperative gross hematuria requiring surgical treatment was higher in the early stage of the learning curve, which is also consistent with the results of previous studies.11,12 Among patients with late complications, 4 patients developed urethral stricture/bladder neck contracture and 16 patients developed stress urinary incontinence at 3 months and 6 months after TUEB. No significant difference was found in the complication rate according to the learning curve, although Xiong et al.10 reported that the incidence of complications was higher in the initial consecutive TUEB cases.
Our study had several limitations. Because of the retrospective nature of our study, we were unable to include several factors of interest such as postoperative urinary incontinence (e.g., usage of pads) or the impact of training under supervision on the learning curve. Several factors that may impact the operative time, such as the presence of a bladder diverticulum or chronic prostatitis, were also excluded. Because the present study only focused on the learning curve of TUEB, we were unable to compare surgical outcomes according to surgical techniques or perform a subgroup analysis of the impact of preoperative anticoagulant use. In addition, although we adopted an en bloc enucleation technique in the present study, the early apical release technique (which has recently been introduced into clinical practice) was not performed in the strict sense, especially during enucleation at the 12-o’clock position. Moreover, we had no prostate size-based training curriculum for TUEB as described in previous research.25 Because the present study was based on the experience of a single operator, the ability to generalize our results may be limited. Therefore, further prospective studies based on multiple operators should be performed. Furthermore, our study lacks the long-term follow-up data of functional outcomes or complications at >1 year. This is partially because our institution is a tertiary hospital, and many patients thus returned to community medical centers for postoperative follow-up. Despite these limitations, our research is a noteworthy addition to the small number of existing studies evaluating the learning curve of TUEB.
CONCLUSIONS
Our results suggest that TUEB may be an effective and safe surgical treatment option for BPH. The surgical efficiency of TUEB reached stability within 70 consecutive procedures. Further analyses of the learning curve may be necessary to explore the long-term outcomes and complication rates.
AUTHOR CONTRIBUTIONS
BS and SJJ contributed to the protocol and project development, contributed to the manuscript writing and editing, and were involved in the critical review. SJJ performed the surgical procedures and supervised the study. BS and SHS were involved in the data collection, analysis, and management. All authors read and approved the final manuscript.
COMPETING INTERESTS
All authors declare no competing interests.
Supplementary Information is linked to the online version of the paper on the Asian Journal of Andrology website.
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