Enucleation Ratio as a Novel Predictor of Symptomatic Improvement After HoLEP

HoLEP has become a widespread and well-practiced surgical method for benign prostate obstruction (BPO). The method is known to have a steep learning curve, and mastery requires extensive practice. Treatment efficiency depends on removing the obstruction while protecting the delicate external urethral sphincter.

However, it's still unclear which pre-operative and intra-operative factors affect surgical outcome. Some authors have already contributed to this subject; in fact, changes in peak urinary flow rate, IPSS-QoL, and the absence of stress urinary incontinence and high-grade complications are among the agreed-upon criteria for successful surgery. As the main purpose of HoLEP, or any other benign prostate surgeries, is to remove obstruction, the more adenoma tissue to be removed, the less obstruction there will be. Yet not anatomic, but there's a surgical capsule around the prostate, which can stretch, causing residual tissue to obstruct the urethral passage. Leaving residual adenoma tissue is not uncommon and may affect the efficacy of HoLEP, particularly given the steep learning curve of the procedure. Therefore, it may be reasonable for one to consider that the higher the ratio of adenoma tissue removed, the better the outcomes could be.

Enucleation ratio is a novel parameter that has not been investigated previously in this context and is calculated by dividing the weight (grams) of morcellated adenoma tissue by the preoperatively measured prostate volume (mL). The density of the prostate is widely accepted as 1 gram per milliliter, so the enucleation ratio has no units.

Identifying a minimum enucleation ratio associated with clinically meaningful symptomatic improvement could provide surgeons with a measurable intraoperative target, potentially improving procedural standardization and patient counseling - particularly during the learning curve of HoLEP.

• Holmium laser enucleation of prostate (HoLEP) (Procedure): HoLEP is a widespread and minimally invasive surgical method to treat LUTS caused by BPO. En-bloc or tri-lobar technique will be performed according to the surgeon's preference during the procedure.

Primary outcomes

• Achievement of mild symptom category (IPSS < 8) at 3 months after HoLEP [3 months after HoLEP]: The International Prostate Symptom Score (IPSS) is a validated questionnaire for lower urinary tract symptoms (LUTS). An IPSS score of 1-7 indicates mild LUTS, 8-19 moderate, and 20-35 severe LUTS, according to both the AUA and the EAU. Achievement of mild LUTS (IPSS < 8) is widely accepted as a satisfactory surgical outcome. Therefore, the primary outcome was set as binary (IPSS < 8 or otherwise). 3 months as a postoperative period is preferred because relief of irritative symptoms requires time, and the 3-month timepoint is widely adopted in the HoLEP literature as the standard assessment period for functional outcomes, allowing sufficient recovery from transient postoperative irritative symptoms while reflecting stable surgical results.

Secondary outcomes

• QoL score reduction of at least 1 point from the baseline at 3 months after HoLEP [3 months after HoLEP]: The Quality of Life (QoL) score is a single validated question included in the IPSS questionnaire that assesses how much lower urinary tract symptoms affect a patient's daily life, scored from 0 (delighted) to 6 (terrible). 3 months as a postoperative period is preferred because relief of irritative symptoms requires time, and the 3-month timepoint is widely adopted in the HoLEP literature as the standard assessment period for functional outcomes, allowing sufficient recovery from transient postoperative irritative symptoms while reflecting stable surgical results.
• Qmax > 15 mL/s achievement rate at 3 months after HoLEP [3 months after HoLEP]: Maximum urinary flow rate (Qmax) is an objective measure of voiding efficiency assessed by uroflowmetry. A Qmax of 15 mL/s is widely accepted as the threshold distinguishing normal from impaired voiding, as referenced in EAU guidelines for non-neurogenic male LUTS. 3 months as a postoperative period is preferred because relief of irritative symptoms requires time, and the 3-month timepoint is widely adopted in the HoLEP literature as the standard assessment period for functional outcomes, allowing sufficient recovery from transient postoperative irritative symptoms while reflecting stable surgical results.
• Ratio of high grade complications (Clavien-Dindo grade III or higher) within 1 month after HoLEP [Within 1 month following HoLEP]: In large HoLEP series, 30-day postoperative complications have been consistently reported using the Clavien-Dindo classification.
• Ratio of stress urinary incontinence at 3 months after HoLEP [3 months after HoLEP]: Stress urinary incontinence, whether transient or permanent, is a well-recognized complication of HoLEP, and its absence at 3 months postoperatively is among the criteria for Trifecta achievement as defined in the literature.

Other outcomes

• PVR-R change 3 months after HoLEP [3 months after HoLEP]: Post-void residual ratio (PVR-R) is calculated by dividing post-void residual volume by total bladder capacity, both obtained from uroflowmetry. Although PVR-R is referenced in the EAU guidelines on urinary incontinence, it has not yet been established as a standard outcome measure in the BPH surgery literature. Nevertheless, expressing post-void residual as a ratio relative to total bladder capacity may offer a more individualized and reproducible measure compared to absolute volume alone, and its exploratory assessment following HoLEP may contribute to future standardization of voiding outcomes.
• tPSA change 3 months after HoLEP [3 months after HoLEP]: Total prostate-specific antigen (tPSA) is expected to decline following HoLEP due to the removal of adenoma tissue, and its postoperative change may serve as an indirect indicator of enucleation completeness. Furthermore, as preoperative tPSA correlates with prostate volume - from which the enucleation ratio is derived - it is considered a potential confounder in the primary analysis and will be assessed exploratorily to better understand its relationship with both the predictor and the primary outcome.

Sex: Male, ages: 18 Years to any

Inclusion Criteria:

* Men aged 18 years pr older who are planned to undergo HoLEP.
* Participants who are willing to give informed consent.
* Participants who have moderate to severe LUTS (referring to IPSS score 8 points or more).
* No history of previous prostate or urethral surgery.

Exclusion Criteria:

* Unwillingness to provide informed consent.
* Unwillingness to provide contact information or unreachability during follow-up periods.
* Incidental diagnosis of a urogenital malignancy requiring primary treatment after enrollment (e.g., bladder tumor, renal cell carcinoma, testicular tumor).

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• Murat Gulsen, Assistant Professor, Principal investigator, Ondokuz Mayıs University