Influence of 980-nm Diode Laser Vaporization on Sexual Function: A Short-Term Follow-Up Study

Abstract

Objective:

The aim of this study was to assess changes in sexual function after 980-nm diode laser vaporization of the prostate.

Methods:

A total of 82 benign prostatic hyperplasia (BPH) patients underwent 980-nm diode laser vaporization from May 2013 to December 2016, and were followed up for 12 months. The following outcomes were assessed at baseline, 6, and 12 months postoperatively: international prostate symptom score (IPSS), quality of life (QoL) score, maximum urinary flow rate (Qmax), five-item version of international index of erectile dysfunction questionnaire (IIEF-5), male sexual health questionnaire ejaculatory function domain Short Form (MSHQ-EjD Short Form), and retrograde ejaculation.

Results:

Significant improvements at 6 and 12 months were noted postoperatively using IPSS, QoL, and Qmax compared with the preoperative values. Considering both patients and subgroups, the mean postoperative IIEF-5 scores at 6 and 12 months were unchanged compared with baseline. Regarding the MSHQ-EjD Short Form, at 6 and 12 months follow-up, postoperative total score of ejaculation function was decreased because the volume of ejaculation was decreased significantly. The frequency of ejaculation and force of ejaculation were also decreased, but the difference was not statistically significant. No significant difference in ejaculation bother item was observed after the operation. Patients with retrograde ejaculation at 6 and 12 months follow-up increased from 6/82 (7.3%) to 38/82 (46.3%), 42/82 (51.2%).

Conclusion:

The sexual function of patients could be maintained after 980-nm diode laser vaporization of prostate with the exception of reduction of ejaculatory volume and retrograde ejaculation.

Introduction

Transurethral resection of the prostate (TURP), the gold standard of surgical treatment for benign prostatic hyperplasia (BPH), has been used worldwide for 30 years.¹ However, complications including blood loss, transurethral resection syndrome, capsular perforation, and influence on sexual function are still significant in patients treated with TURP. These potential deficiencies have resulted in the pursuit of more attractive and less invasive surgical treatments. Therefore, excellent minimal invasive devices have been introduced rapidly and become new accepted alternatives to TURP during the last few years.

A diode laser at 980-nm wavelength can be absorbed by water and hemoglobin simultaneously. Furthermore, it can provide superior tissue vaporization capacity and perfect coagulation property.² Previous studies had demonstrated the efficacy and safety of this laser, and it had become an attractive alternative to TURP due to its bloodless, efficient, and shorter learning curve characteristics.^2

–5 Previous data seem exciting; however, few studies reported the effect of this surgical treatment on sexual function. Our study aims to assess the influence on sexual function in BPH patients who underwent 980-nm diode laser vaporization prostatectomy.

Patients and Methods

Study design

From May 2013 to December 2016, we designed a study on changes of sexual function in BPH patients who underwent 980-nm diode laser vaporization prostatectomy. Our study received the approval of the Ethical Committee of the hospital. Eighty-two BPH patients were eligible to enroll in the study. We had an indication for surgical treatments according to EAU guidelines.⁶ The inclusion criteria were failure of previous treatment of drugs, maximum urinary flow rate (Qmax) <15 mL/s, total serum prostate-specific antigen (TPSA) <4 ng/mL or TPSA = 4 to 10 ng/mL with negative prostate biopsy, and international index of erectile dysfunction questionnair (IIEF)-5 > 11. Patients were excluded from the study if they had a history of urethral stricture, neurogenic bladder, prostate cancer, other malignant tumor, or prostatic surgeries. Patients treated with testosterone or phosphodiesterase type 5 inhibitors before 6 months were excluded. Patients with disease affecting sexual function, including uncontrolled diabetes, hepatic dysfunction, and serious cardiovascular disease, were also excluded. In addition, patients who had no sexual partner or a postoperative follow-up <1 year were not included.

At the initial consultation, patients underwent a baseline evaluation that included the following: a digital rectal examination, prostate-specific antigen (PSA), prostate volume by ultrasound, international prostate symptom score (IPSS), quality of life (QoL) score, and urodynamic examination. To estimate changes in sexual function, two validated questionnaires (IIEF-5^7,8 and MSHQ-EjD [male sexual health questionnaire ejaculatory function domain] Short Form⁹) were used. The IIEF-5 questionnaire was used to determine the erectile function of patients (the IIEF-5 score standard: no erectile dysfunction (ED) [22–25], mild ED [17–21], mild-to-moderate ED [11–16], moderate ED [8–10], and severe ED [5–7]).^7,8 To evaluate the ejaculation function of patients, we used a simplified MSHQ-EjD Short Form questionnaire. Contents of the questionnaire included three ejaculatory function items (ejaculatory force, ejaculatory volume, and ejaculatory frequency) and one ejaculation bother/satisfaction item. Both the ejaculation force and ejaculation volume scores range from 0 to 5 points, the frequency of ejaculation score ranges from 1 to 5 points, the total ejaculatory function score, which is the sum of three items, ranges from 1 to 15 points (normal: 12–15, ejaculatory dysfunction: 1–11). The bother/satisfaction score ranges from 0 to 5 points. Retrograde ejaculation is regarding patients who have ejaculation action and pleasure during the process of sexual intercourse, but no or only a small amount of seminal fluid excreted from the external urethral orifice. At 6 and 12 months follow-up, IPSS, QoL, IIEF-5, and MSHQ-EjD Short Form questionnaires were repeated. Qmax was obtained through a repeat uroflowmetry. Men were also asked about the occurrence of retrograde ejaculation specifically. All questionnaires were completed by patients themselves or with the help of the registrar if patients were unable to understand.

Surgical procedure

All operations were performed by a single senior doctor according to a routine procedure. The surgery used a semiconductor red laser surgery system (Biolitec-AG, Germany), with 70°- side-firing laser fiber emitting red light at a wavelength of 980 nm. All the patients received side-fiber vaporization. The laser beam at this side-firing fiber is directed by a bare fiber sideways onto the prostate tissue to permit vaporization. Firstly, we should observe anatomical position of verumontanum and ureteral orifices avoiding ablating them. The vaporization began from 5 to 7 o'clock, and the initial power was set at 80 to 90 W. The power could be increased to 120 W when widening the cavity until prostate tissue causing obstruction was removed. During the operation, the laser fiber was used near the bleeding region to achieve hemostasis, avoiding direct contact with the tissue. Generally speaking, the lateral lobes were vaporized at first, and the middle lobe, if present, was vaporized after completing the lateral lobe vaporization. To preserve ejaculatory function, the periverumontanum prostate tissue should be preserved. A lower power should be set especially at the sensitive areas such as the prostatic apexes and around the sphincteric area, and the area should be vaporized smoothly during operation. At the end, a 22-F three-way Foley catheter was inserted and irrigated with saline intermittently. The catheter was removed when urine became clear after operation, taking into consideration the degree of hematuria. Drugs affecting the erectile function should not be used during the perioperative period.

Statistical methods

The results of clinical parameters are shown as mean ± standard deviation or number of cases (percentage). Categorical data were analyzed by chi-square, and continuous data were analyzed by paired t-test. Statistical data were analyzed by IBM^® SPSS^® Statistics version 19.0. A two-sided p value <0.05 was considered statistically significant.

Results

A total of 82 patients underwent 980-nm diode laser vaporization of the prostate, who met the inclusion criteria and completed the preoperative and postoperative questionnaires during the study period. The baseline characteristics are summarized in Table 1. Of 82 patients, 12 patients (14.6%) reported baseline hypertension, 3 patients (3.66%) had a history of diabetes, and no patients reported a coronary heart disease history. Perioperative variables associated with patients, including operation time, duration of catheterizations, and hospital stays, are shown in Table 1. The results of Qmax, IPSS, and QoLs at 6 and 12 months of follow-up are summarized in Table 2. Statistically significant increase of these urinary functional values was compared with the preoperative values.

Table 1.

Baseline Patient Characteristics and Perioperative Variables

Variable	Mean ± SD (range) or no. of patients (%)
Baseline characteristics
Age (year) (52–79)	68.07 ± 6.90
BMI (kg/m²)	23.78 ± 3.20 (17.72–31.53)
Prostate volume (mL) (25–88)	56.51 ± 13.48
Total PSA (ng/mL) (0.26–9.91)	3.78 ± 2.84
Hypertension	12 (14.6)
Coronary heart disease	0
Diabetes mellitus	3 (3.66)
Perioperative variables
Operative time (minutes)	78.72 ± 27.13 (30–175)
Duration of catheterization (days)	2.39 ± 0.58 (1–4)
Hospital stay (days)	6.89 ± 3.12 (3–18)

BMI = body mass index; PSA = prostate-specific antigen; SD = standard deviation.

Table 2.

The Changes in Preoperative and Postoperative International Prostate Symptom Score, Quality of Life, Maximum Urinary Flow Rate

Variable	Baseline	6 Months	12 Months	p^a	p^b	p^c
Qmax	7.1 ± 2.3	16.2 ± 2.6	16.5 ± 2.3	<0.001	<0.001	0.243
IPSS	21.6 ± 5.2	7.2 ± 1.9	7.0 ± 1.9	<0.001	<0.001	0.109
QoL	5.3 ± 0.9	2.1 ± 0.9	2.0 ± 0.7	<0.001	<0.001	0.254

Preop vs 6 months.

Preop vs 12 months.

6 vs 12 months.

IPSS = international prostate symptom score; Qmax = maximum urinary flow rate; QoL = quality of life changes.

As shown in Table 3, considering all patients, preoperative IIEF-5 score and postoperative IIEF-5 score at 6 and 12 months were 17.24 ± 3.25 vs 17.23 ± 3.04 and 17.24 ± 3.25 vs 17.04 ± 3.59, respectively. When patients were classified under erectile dysfunction categories: moderate–mild, mild, and normal, no statistically significant difference was found in IIEF-5 scores. Regarding the MSHQ-EjD Short Form, postoperative total score of ejaculation function at 6 and 12 months of follow-up was decreased because of the significant reduction of ejaculation volume scores. The frequency of ejaculation and force of ejaculation were also decreased, but the difference was not statistically significant. No significant difference in ejaculation bother item was observed after the operation. Upon analysis of the retrograde ejaculation, 6 patients (7.3%) showed retrograde ejaculation preoperatively. At 6 and 12 months of follow-up, patients with retrograde ejaculation were increased by 38 (46.3%) and 42 (51.2%).

Table 3.

Changes in Postoperative Scores on IIEF-5 and MSHQ-EjD Short Form

Variable	Preoperation	6 Months	12 Months	p^a	p^b	p^c
IIEF-5	17.24 ± 3.25	17.23 ± 3.04	17.04 ± 3.59	0.057	0.074	0.184
No ED (n = 3)	23.00 ± 1.00	21.67 ± 1.15	21.00 ± 1.00	0.178	0.230	0.749
Mild ED (n = 47)	19.32 ± 1.27	19.21 ± 1.14	18.96 ± 1.49	0.452	0.130	0.239
Mild-to-moderate ED (n = 32)	13.66 ± 1.45	13.91 ± 1.71	13.84 ± 1.44	0.187	0.462	0.810
EjD score	8.27 ± 1.99	7.20 ± 1.57	7.04 ± 1.38	<0.001	<0.001	0.074
Frequency of ejaculation	3.12 ± 0.95	3.04 ± 0.96	3.01 ± 0.84	0.163	0.181	0.672
Force of ejaculation	2.68 ± 0.92	2.73 ± 0.67	2.65 ± 0.64	0.453	0.664	0.109
Volume of ejaculation	2.46 ± 0.59	1.43 ± 0.56	1.38 ± 0.56	<0.001	<0.001	0.103
Bothersome score	2.39 ± 0.60	2.30 ± 0.46	2.29 ± 0.60	0.109	0.239	0.219
Retrograde ejaculation, n (%)	6 (7.3)	38 (46.3)	42 (51.2)	<0.001	<0.001	0.639

Preop vs 6 months.

Preop vs 12 months.

6 vs 12 months.

EJF = ejaculation function; IIEF = International Index of Erectile Function; MSHQ-EjD = male sexual health questionnaire ejaculatory function domain.

Discussion

Ejaculation, defined as the seminal fluid excreted from urethra, consists of three stages: emission, ejection, and orgasm.¹⁰ The ejaculatory reflex is mainly controlled by some neurotransmitters, such as serotonin, dopamine, adrenaline, and acetylcholine.¹¹ Male sexual dysfunctions generally involve three important components: ejaculatory disorders (EjDs), erectile dysfunction, and hypogonadism.¹² EjD is the most common male sexual dysfunction. EjDs comprise a group of dysfunctions that involve premature ejaculation or delayed ejaculation, anejaculation or retrograde ejaculation, perceived reduction of ejaculation volume, or decreased force of ejaculation.¹⁰ Despite being most common among male sexual dysfunction, the onset of EjDs may involve many physical and psychological factors and remains poorly understood.

Nowdays, BPH has become a public health problem. With a growing concern for postoperative QoL, patients pay more attention to sexual function after operation in the choice of surgical treatments. As an early surgery treatment, TURP solves many problems of open surgery, but has certain influence on sexual function among BPH patients. However, its effect on sexual function is still controversial. Poulakis et al.¹³ evaluated the change in sexual function after TURP with IIEF-5 questionnaire; the results showed that TURP had an impact on postoperative sexual function, and the incidence of ED was 12%, and the main factors affecting sexual function were intraoperative perforation of prostatic capsule and diabetes. Muntener et al.¹⁴ held different views on sexual function; their study suggested that TURP had no effect on erectile function among BPH patients after operation, and patients had an improvement in ejaculatory function and distress symptom postoperatively. Other studies showed that risk factors associated with ED were capsular perforation, small-sized prostate, high energy used during operation, and preoperative pre-existing diseases, including diabetes mellitus and cardiovascular disease.^15,16

Laser-based techniques for BPH patients have developed rapidly in recent years, such as holmium laser,^17,18 green laser,^19,20 thulium laser,^21
–23 and diode laser. Previous studies²⁴ showed that laser-based techniques have little effect on the erectile function after surgery. Bruyere and colleagues²⁴ used the IIEF-5 score to asess the change of sexual function in 149 patients preoperatively and at 1, 3, 6, 12, and 24 months after photoselective vaporization of the prostate (PVP) with the GreenLight laser. The data showed that patients could maintain sexual function after operation. However, there was a significant decrease in ejaculation function (EF) for patients with normal preoperative EF (IIEF-5 ≥ 19). Carmignani et al.²⁵ designed a prospective study on 110 consecutive patients who underwent ThuLEP to evaluate changes in sexual function. After 6 months of follow-up, no significant differences in erectile function were observed after surgery, and the percentage of patients with conserved ejaculation increased by 52.7%.

The 980-nm diode laser vaporization prostatectomy has gained popularity as an effective and safe surgery for BPH patients. To our knowledge, few studies had discussed the effect of 980-nm diode laser on sexual function of patients after operation. To fully evaluate the effects of 980-nm diode laser on sexual function, our study combined IIEF-5 with MSHQ-EjD Short Form. IIEF-5 is the international questionnaire for evaluation of erectile function, but it has some limitations that lack in overall evaluation of the change of sexual function, such as insufficient assessment of ejaculation, the semen volume, and the degree of satisfaction.⁷ In recent years, MSHQ-EjD Short Form questionnaire, which is gradually applied in related research, evaluates sexual function based on ejaculation, sexual satisfaction, sexual desire, and related psychological factors.⁹ Capsular perforation adjacent to the neurovascular bundles indued by chemical or thermal injury is a main risk factor for the erection impairment. Previous studies showed that ∼6% of patients experienced capsular perforation during TURP.²⁶ In contrast, our data showed that none of the patients experienced capsular perforation. Moreover, at the 6 and 12 months follow-up, our results showed that 980-nm diode laser vaporization does not affect erectile function of patients. Postoperative IIEF-5 scores were unchanged compared with baseline, which revealed that the effect of erectile function after 980-nm diode laser vaporization prostatectomy was low. According to MSHQ-EjD Short Form, the frequency of ejaculation, force of ejaculation, and bothersome scores were not changed significantly before and after operation. Possible reason was due to the special wavelength of 980 nm with high simultaneous rate of absorption in water and hemoglobin. These superior characteristics of the laser had decreased the risk of capsular perforation and erectile nerve vascular bundle injury. Seitz and colleagues²⁷ compared the effects of diode lasers, Ho YAG, and KTP, on ex vivo porcine kidney. They observed that diode laser had a 10-fold better coagulation capacity and a larger coagulation zone than other lasers during high-intensity diode laser ablation of the prostate, demonstrating the usefulness of diode lasers with excellent homeostasis in the treatment of BPH. 980 nm diode laser acted directly on prostate hyperplasia tissue and the penetration depth was superficial (< 1 mm), some areas may be 0.29 mm.²⁸ Due to the laser's superficial coagulation zones, there is no harm to the underlying structures such as the neurovascular bundles and the external sphincter, which may cause erectile dysfunction and incontinence. As blood supply and oxidation of hemoglobin of prostatic capsule are less rich, the efficiency is reduced obviously upon laser vaporization near prostate capsule. To reduce influence of postoperative sexual function, we should control the depth of vaporization accurately and avoid thermal damage to nerve vessel bundles caused by prostatic capsular perforation. Keeping a clear vision and operating gently are important. When close to the prostate capsule, the laser power should be reduced, especially at the 5 and 7 points in the apex of prostate. Moreover, the sensitive areas such as prostatic apexes and verumontanum should be noteworthy, which may lead to postoperative bleeding and urinary incontinence when given inappropriate treatment.

Retrograde ejaculation is a common complication after prostatectomy. Kaya et al.²⁹ had reported an equivalent outcome of retrograde ejaculation in 75 cases of BPHwho underwent plasmakinetic vaporization of prostate (PKVP) and TURP, with 56% and 60% incidence of retrograde ejaculation, respectively, after 3 years of follow-up. Carmignani et al.²⁵ used ICIQ-MLUTSsex, MSHQ-EjD, and IIEF-5 questionnaires preoperatively and postoperatively; their results showed that an overall conservation rate of antegrade ejaculation was 52.7% for patients who underwent thulium laser enucleation of the prostate (ThuLEP). In our study, the incidence rates of retrograde ejaculation at 6 and 12 months postoperatively were 46.3% and 51.2%, respectively. During the follow-up, we observed that patients with obvious hyperplasia of prostatic middle lobe appeared to have higher rates of retrograde ejaculation. The reason might be that these patients often need to ablate more bladder neck tissue during surgery to relieve symptoms of lower urinary tract obstruction. Consequently, bladder neck could not be closed normally resulting in retrograde ejaculation, hence preserving the internal sphincter as much as possible and maintaining the integrity of the bladder neck might be an effective way to preserve antegrade ejaculation after surgery. However, the importance of bladder neck is still controversial. Talab and Bachmann³⁰ showed that regardless of preserving antegrade ejaculation, the important factor was high-pressure ejaculatory zone (the muscular tissue proximal to and around the verumontanum) rather than the bladder neck contraction. Their results showed that preserving the muscular tissue around the verumontanum, patients could still maintain antegrade ejaculation even with an open bladder neck.^30,31

Another change of sexual function after prostatectomy was reduction of the amount of semen. Our results showed that volume of ejaculation was decreased after operation. The reduction of prostate fluid after operation might be due to low volume of semen. The prostatic fluid, a kind of thinnest and colorless acid emulsion, was a major component of semen.

In addition, postoperative IPSS, QoL, and Qmax were improved significantly in our study. At 6 months follow-up, significant improvements were noted in IPSS (7.2 ± 1.9), QoL (2.1 ± 0.9), and Qmax (16.2 ± 2.6 mL/s) (p < 0.001). Data also showed that significant improvements were sustained at 12 months after the operation (p < 0.001). We considered that with the improvement of LUTS symptoms, postoperative sexual function of patients can be maintained accordingly. Our results also showed that the 980-nm diode laser vaporization prostatectomy was safe for patients. Some patients had the symptoms of secondary hematuria, urinary tract infection, transient urinary incontinence, and dysuria in our study. However, these symptoms disappeared after symptomatic treatment. During our study, three patients developed hematuria 2 days after removal of the catheter, and an indwelling catheter was inserted with bladder irrigation. After 3 days, the hematuria disappeared. Five patients with mild urinary tract infection and the symptoms disappeared after anti-inflammatory treatment for 3 days. Six patients with transient urinary incontinence and the symptoms disappeared after treating with M receptor blocker (tolterodine tartrate) and levator anal muscle training. Five patients had a brief dysuria after removal of the catheter. The symptoms disappeared after treating with a receptor blocker. No patients suffered serious complications such as permanent incontinence and blood transfusion, and needed reoperation.

One of the drawbacks of the 980-nm diode laser vaporization prostatectomy is that less tissue is retrieved for histology, most prostate tissues are vaporized during operation, the missing tissue caused by vaporization should be paid attention; therefore, the digital rectal examination, PSA, and a negative prostate biopsy are important to exclude cases of prostate cancer before surgery. Moreover, the cost of laser equipment may be considered another shortcoming of the technique. Other limitations were also worthy of note in our study; first, the lack of control groups and assessment by the partner. Restricted by the conditions, the number of related research cases in this study was relatively small, and the follow-up time was not long. Second, although the postoperative change of sexual function was observed specifically at each follow-up, unfortunately we could not assess it completely as we did not use an objective tool to assess the changes. Third, we did not perform an analysis of risk factors affecting sexual function.

Conclusion

According to our study, as a minimally invasive operation, 980-nm diode laser vaporization prostatectomy has little effect on sexual function of BPH patients. However, retrograde ejaculation and reduction of ejaculation volume need clinical attention. The percentage of patients with retrograde ejaculation were 46.3 (38/82) and 51.2 (42/82) at 6 and 12 months of follow-up after operation, respectively. Controlling for the depth of vaporization accurately and avoiding thermal damage to nerve vessel bundles caused by prostatic capsular perforation are important for the whole operation. Further studies with larger population and multicenter studies are needed to fully validate these findings.

Footnotes

Acknowledgments

This work was financed by grants from Guangxi Health Department Scientific Research Program (Z2014384, Z20180483) and Youth Science Foundation of Guangxi Medical University (GXMUYSF201708).

Authors' Contributions

M.W. conceived idea, designed research, and revised the article; L.H. and J.H. designed subsequent experiments, performed most of the work, and prepared the article; Y.F. helped to analyze the study data.

Author Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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