Photoselective vaporization of the prostate with the potassium-titanyl-phosphate laser in men with prostates of >100 mL


Krishnamoorthy Rajbabu, Department of Urology, King’s College Hospital, London SE5 9RS, UK.



To assess the efficacy of photoselective vaporization of the prostate (PVP) in men with prostates of >100 mL and causing bladder outlet obstruction (BOO), using the high-power 80 W potassium-titanyl-phosphate laser (GreenLight PV®, Laserscope, San Jose, CA, USA), which offers rapid tissue ablation with minimal bleeding.


We assessed 54 consecutive patients with prostates of >100 mL (mean 135, sd 42, range 100–300) who had PVP between May 2003 and August 2005. Evaluations before PVP included urine flowmetry, the International Prostate Symptom Score (IPSS), a quality-of life (QoL) score, prostate-specific antigen (PSA) level, and prostate volume measured by transrectal ultrasonography (TRUS).


The mean (sd, range) duration of PVP was 81.6 (22.9, 39–150) min, the mean energy used for PVP was 278 (60, 176–443) kJ and the mean duration of catheterization after PVP was 23.0 (17.1, 0–72) h. The mean (sd) maximum urinary flow rate improved from 8.0 (3.1) to 18.2 (8.1), 18.5 (9.2), 17.9 (7.8) and 19.3 (9.8) mL/s at 3, 6, 12 and 24 months, respectively. The IPSS and QoL scores showed similar improvements, and there was a statistically significant reduction in PSA level and prostate volume after PVP. There was no major complication and no patient had transurethral resection syndrome or a blood transfusion.


The 80 W KTP laser PVP offers rapid tissue ablation in patients with BOO caused by a large prostate. The short- and medium-term outcomes show that this technique can be a viable alternative to open prostatectomy.


photoselective vaporization of the prostate




postvoid residual volume


Quality-of-Life (score)


maximum urinary flow rate.


TURP is considered the standard treatment for men with BPH [1], but because of the risks of bleeding and TUR syndrome, patients with large prostates are usually offered open prostatectomy, which provides excellent removal of prostatic tissue. However, the need for an abdominal incision, prolonged hospitalization and recovery are major disadvantages, whilst there is also a significant risk of perioperative haemorrhage. Open prostatectomy also carries the risk of erectile dysfunction (3–5%), retrograde ejaculation (80–90%) and bladder neck contracture (2–3% in the first 12 weeks) [2]. Although some experts feel that prostates of >75 g should be treated by ‘open surgery’[2], there is no consensus on this issue. Significantly many such patients might be unsuitable for open surgery due to other comorbidities, yet TURP in these patients carries grave risks in terms of irrigant absorption and bleeding [3]. In a contemporary series analysing open prostatectomy for benign prostatic enlargement, severe bleeding (11.6%) and increased blood transfusion rates (8.2%) were reported [4]. The major advantages of open prostatectomy over TURP are a lower re-operation rate, more complete removal of the hyperplastic adenoma, and avoiding the TUR syndrome. The latter occurs in ≈ 2% of patients undergoing TURP [3], although no studies have addressed the expected rate of TUR syndrome in men with very large prostates. The main driver for the decision is the risk of open pelvic surgery, which in addition to the above complications include deep vein thrombosis, risk of pulmonary embolus and complications related to haemodynamic instability due to bleeding in high-risk cardiovascular patients. These risks must be assessed against the risk of TURP lasting >40 min, because TURP with a hyponatraemic solution has a significantly greater risk of bleeding requiring transfusion, and of dilutional hyponatraemia; these are significant contributors to cardiovascular complications related to the haemodynamic instability produced by a lengthy TURP procedure. Thus, the decision for open surgery vs TURP generally rests on the attitude of the surgeon towards these procedures for what is considered a ‘large’ prostate.

In the last 15 years many efforts have been made to identify alternative surgical techniques capable of replacing TURP, but with minimal morbidity. Alternative treatment options for the surgical management of BPH are varied and include needle ablation, electrovaporization, vaporization resection, laser, microwave therapy and ultrasound [5–11]. Techniques using lasers gained wide acceptance because of their favourable safety profile. However, drawbacks of the initial laser techniques included a longer catheterization than with standard TURP, and significant dysuria attributable to coagulative necrosis. The medium-term durability has also been a concern.

Photoselective vaporization of the prostate (PVP) using the GreenLight® system (Laserscope, San Jose, CA, USA) offers an option with less bleeding and absorption than TURP, and has immediate tissue debulking properties [12–15]. Hai and Malek [15] reported their initial experience with high-power potassium-titanyl-phosphate (KTP) laser technology. In their pilot study using the 80 W laser, the mean prostate size was 43 mL and they reported a reduction in the mean prostate volume by 27%. It was thought that glands of >60 mL might require more time than desired, or that a modification in technique might be required to adequately treat a gland of >60 mL. Despite the longer procedure, the risk of bleeding and dilutional hyponatraemia is considerably less, offering an attractive alternative for these patients. Thus we aimed to assess the safety and efficacy of PVP using the high-power 80 W KTP laser for treating patients with BOO caused by a large prostate of >100 mL.


We analysed prospectively 54 consecutive patients (mean age 69 years, range 53–90) with large prostates of >100 mL who were treated using the Greenlight system for PVP, under the care of two consultant urologists (G.H.M. and K.W.) between May 2003 and August 2005. Before PVP, 20 patients (37%) had an indwelling catheter for acute urinary retention. Six patients who were on warfarin (11%) were converted to shorter-acting agents before PVP and warfarin restarted after surgery.

The evaluation before PVP included a clinical history and a DRE, uroflowmetry and an estimation of postvoid residual volume (PVR, excluding those with an indwelling catheter). All patients except those in retention completed the IPSS and Quality-of-Life (QoL) score, had their serum PSA measured, and their prostate volume assessed using TRUS. Patients with high age-specific PSA level had TRUS and a biopsy. Those with prostate cancer and men with neurogenic bladder dysfunction were excluded from the study.

The eligibility criteria included patients with a maximum urinary flow rate (Qmax) of <15 mL/s, an IPSS of ≥8 and a prostate of >100 mL. Patients were, if medically fit, given the option of open prostatectomy; all patients provided informed consent for laser PVP.

Six surgeons (two consultants and four trainees of varying grades) performed the PVP; both consultants had gained 6 months’ experience with the GreenLight system in prostates of various sizes before starting to treat large prostates. A general anaesthetic was used in all patients; a prophylactic antibiotic was given to all at induction, which was continued for 5 days after PVP. The prostate was vaporized with an 80-W KTP side-firing laser system through a 23 F continuous-flow cystoscope. The GreenLight KTP laser emits green light at 532 nm using a near-contact side-firing fibre with emission angle of 70°. The prostate was vaporized in the near-contact mode from the bladder neck area, sweeping spirally downward to the verumontanum. Vaporization is usually begun at the middle lobe. Once this and the bladder neck are dealt with, the proximal lateral lobes are dealt with, sometimes in several stages, before finally coming down to the floor of the prostate and the apex. This allows a clear cavity to develop in a stepwise fashion. A high-standard video camera system was used. Normal saline was used as the irrigant in all cases. The vaporization procedure was stopped when a generous TURP-like cavity was achieved. Catheterization at the end of the procedure was entirely at the operating surgeon’s discretion, and a decision to catheterize was generally based on the amount of energy delivered, perceived haematuria and preoperative PVR.

Patients were followed at 3, 6 and 12 months, and annually thereafter, with a mean follow-up of 28.2 months. Due to the referral nature of our practice, which draws patients from throughout the UK, we were unable to obtain full follow-up in all patients, as not all would attend for the physical follow-up. At each visit the patient completed the IPSS questionnaire, and provided a measurement of urinary flow and PVR. In addition, at the 6- and 12-month visit their serum PSA level as measured. The prostate volume was measured at 3 months in 38 (70%) patients; the reasons for missing this repeat volume measurement included patients being followed elsewhere, patient refusal, and anal pain.

The results were analysed statistically using Wilcoxon signed-ranks test and paired-sample t-tests for statistical significance, with P < 0.05 considered to indicate statistical significance.


In the 54 patients who had PVP the initial mean (sd, range) prostate volume measured by TRUS was 135 (42, 100–300) mL, the mean PSA level was 9.6 (8.3, 1.7–51.6) ng/mL, the mean operative duration was 81.6 (22.9, 39–150) min and the mean energy used for PVP was 278 (60, 176–443) kJ. In all, 16 patients who required >300 kJ needed two laser fibres, while the remaining 38, excluding one, required one laser fibre for vaporization. In this last patient a second fibre was required, as the first was damaged due to extensive contact with the prostate tissue, and the total energy delivered was 190 kJ. One patient had a ‘mini-TURP’ at the end of the procedure to remove an apical flap (2.5 g), as the ureteric orifices could not be seen with the laser telescope.

After PVP 13 patients (24%) required no catheter, while two (4%) needed re-catheterization after removing the catheters a few hours after surgery. The mean duration of catheterization was 23.0 (17.1, 0–72) h and the mean duration of hospitalization after surgery was 11.0 (10.8, 0–48) h. In general, patients operated on a morning list tended to go home on the day of surgery, while those operated on an afternoon or evening list stayed one night, with an overnight catheter. No patient required a blood transfusion. The mean haemoglobin level before and after surgery was 13.7 (1.9, 10.3–15.7) and 13.3 (1.9, 10.0–15.1) g/dL, respectively. There was no clinical TUR syndrome and no patient had a decrease in serum sodium of >5 mmol/L during surgery. The mean serum sodium levels before and after surgery were 139.2 (2.3, 135–146) and 138.9 (2.0, 134–144) mmol/L, respectively.

Of the 39 catheterized patients, six (15%) had overnight irrigation (for 12 h) after surgery, with none requiring manual washouts for clot retention.

In the first 30 days after surgery, six patients (11%) needed treatment for either bleeding or infection; four of these had urinary retention before PVP, with indwelling catheters. Four patients (7%) had one episode of gross haematuria with clot retention at 2–4 weeks after PVP, due to secondary haemorrhage, and required a short course of Foley catheterization and continuous bladder irrigation. One of these patients had to be taken to the operating room for cystoscopy and bladder washout. Four patients (7%) had a UTI with significant bacteriuria, which resolved promptly with oral antibiotic therapy, with two having both infection and clot retention.

There was urgency after surgery in 12 (22%) patients, which was transient, lasting <1 week in most (nine); in the remaining three (6%), anticholinergics were required to treat the overactive bladder symptoms. Two of them improved with a 3-month course of anticholinergic drugs, while one who continued to have overactive bladder symptoms and urge incontinence despite anticholinergic treatment is being considered for intravesical botulinum therapy. There were no cases of stress incontinence.

In one patient there was a ureteric injury due to end-firing of the laser fibre during surgery; this patient had a huge middle lobe, which can be a problem, as the ureteric orifices are hidden. A 7 F ureteric stent was placed antegradely and left in place for 6 weeks, with a normal IVU at 3 months. Two patients (3.7%, both with preoperative catheters for retention) developed a bulbar urethral stricture 3 months after PVP and required urethrotomy.

Three patients (6%) required a re-operation due to recurrence of LUTS, one at 4 weeks, one at 16 months and one at 18 months after PVP; all three had a successful repeat PVP. The follow-up variables are shown in Table 1 and the complications encountered in the patients listed in Table 2. One patient required open prostatectomy at another hospital for persistent haematuria at 31 months, when 90 mL of tissue was removed. In all four patients who required re-operation, it was noted that during the initial procedure the surgery was limited by bleeding.

Table 1.  The variables before and at the follow-up assessments after surgery
VariableBeforeFollow-up, months
  1. All follow-up values were significantly different from baseline at P < 0.001, Wilcoxon test. *34 patients, excluding those with an indwelling catheter before PVP.

Number of patients5446454838
Mean (sd, range)
Qmax, mL/s* 8.0 (3.1, 3.9–18.0)*18.2 (8.1, 5.5–41.1)18.5 (9.2, 7.7–50.0)17.9 (7.8, 5.0–37.2)19.3 (9.8, 5.1–41.1)
IPSS22.9 (6.8, 8–33)12.2 (7.8, 1–30) 7.8 (4.9, 2–30) 6.3 (4.1, 1–24) 5.7 (3.6, 1–16)
PVR, mL*134 (74, 0–300)53 (81, 0–500)46 (59, 0–300)48 (75, 0–440)49 (61, 0–300)
QoL index 4.8 (0.8, 3–6) 3.2 (1.7, 0–6) 1.8 (1.0, 0–5) 1.4 (1.2, 0–5) 1.3 (0.7, 0–3)
Table 2.  The complications encountered
ComplicationN (%)
Intraoperative ureteric orifice damage1 (1.8)
Postoperative irritative symptoms3 (5.5)
UTI5 (9.2)
Secondary haemorrhage4 (7.4)
Urethral stricture (bulbar)2 (3.7)

In all, 38 patients (70%) had a repeat measurement of prostate volume at 3 months after PVP; the volume had reduced from a mean of 138.0 (43.9) before PVP to 75.9 (24.7) mL afterward. The difference was statistically significant (P < 0.001; paired-sample t-test). Interestingly there was no direct correlation between the reduction in prostate volume and energy delivered, at 0.212 (P > 0.05) for 38 patients (Table 3); this is also shown in the scattergram (Fig. 1). In all, 33 patients (61%) had a repeat PSA measurement at 6 months and 30 (55%) at 12 months. The mean PSA level at 6 months was 5.6 (5.7) ng/mL, compared with the baseline of 11.0 (9.3) ng/mL, and that at 12 months was 6.4 (6.0) ng/mL vs the baseline of 11.8 (9.4) ng/mL. The reductions in the PSA level at 6 and 12 months were statistically significant (P < 0.001). As PSA is a surrogate of BPH volume, and PSA is easier to determine then prostate volume by TRUS, it might be that PSA level could be used as a surrogate for volume in future studies, if there are problems in repeating TRUS volumes. The follow-up of these patients and the re-operation rate is shown in Fig. 2.

Table 3. 
The Pearson correlation between the energy delivered and reduction in prostate volume
VariablePVP energyTRUS difference
PVP energy 1 0.212
P (two-tailed)  0.201
TRUS difference 0.212 1
P (two-tailed) 0.201 
Figure 1.

A scattergram showing the relationship between the amounts of energy delivered and change in TRUS volume.

Figure 2.

A flow-chart showing the follow-up of patients and the re-operation rate.


As PVP with the GreenLight system has a favourable safety profile [16,17], we aimed to study the efficacy of this novel technique for treating patients with very large prostates. To avoid any controversy about what constitutes a ‘large’ prostate we assessed only those patients with prostates of ≥100 mL. We started the study as a prospective evaluation of the safety and feasibility of PVP in very large prostates; once the initial data were available (despite these patients representing the learning phase) we considered that randomization between open prostatectomy and laser prostatectomy would have been difficult or impossible when offering the options of a day-case operation vs a major open procedure. Apart from this there would clearly be no realistic way of ensuring that patients or assessors were unaware of the treatment type, so we continued with the open study due to our concerns that recruitment and cross-over bias would make randomization impractical.

In a similar study to the present, Sandhu et al.[18] reported a mean (sd) operative duration of 122.9 (69.7) min with a mean energy of 294 (131) kJ. The mean prostate volume in that study was smaller than in the present, at 101.3 (40.3) mL. The procedure clearly depends on the amount of energy delivered, although we eventually learned to apply more energy in less time. Also, depending on the patients’ comorbidity, some were not treated with optimum amounts of energy, to reduce the intraoperative risks. Reich et al.[19] commented that high-power KTP laser vaporization of the prostate was an ideal one-stage procedure for patients at high risk and for those on anticoagulation.

While there are reports suggesting that laser prostatectomy is safe in patients on anticoagulation, with no increased risk of bleeding complications or need for transfusion [20], we prefer to switch patients from warfarin to low molecular weight heparin before surgery.

There are also reports on the difficulty of achieving haemostasis when bleeding occurs during PVP [12], and it is claimed that effective haemostasis is achieved with 30 W of laser energy [18,21]. Achieving haemostasis when large sinuses are exposed (while very rare) can be challenging; in our experience reducing the laser power to 30–40 W or defocusing the laser beam allows control of bleeding points to maintain a clear field of view.

In some patients we had difficulty with good vision, due to bleeding, with one particular problem being the amount of saline that can flow through the small (21–23 F) endoscopes. A temporary suprapubic catheter can be extremely helpful to enable good vision during the procedure. In the vast majority of cases no adjuncts to improve haemostasis or visibility are needed. Occasionally then surgeon can encounter a large intravesical middle lobe, which can be a problem at the end of vaporization, as a tiny flap of middle lobe can obscure the ureters. In such rare instances it is wise to consider a mini-resection of the residual middle lobe. It is essential to maintain close contact at the bladder neck and carefully monitor the aiming beam direction before vaporising in such cases of large middle lobes. Vaporising is usually started at the bladder neck, but it is also possible to start vaporising the lateral lobe tissue well inside the prostatic urethra. This can also avoid any inadvertent bladder or ureteric orifice injuries in cases of large prostates with large median lobes.

There are few data to date on the overall time taken for PVP and it is generally thought that the laser time is related to the size of the prostate. Malek et al.[22] reported a laser time of 48 min for a 60 mL gland and 94.7 min for a 90 mL prostate, using a KTP laser at 60 W, although with the introduction of the 80-W generator they could not detect a significant difference between the laser times of two groups treated at 60 and 80 W, because of the significantly larger prostatic volumes of the 80 W group. However, in their study, a laser time of 99 min for the largest prostate of 136 mL treated at 80 W was faster than 94.7 min for the largest prostate of 90 mL treated at 60 W. In the present series, although the laser time was generally longer in patients with larger prostates, there was no relationship between the amount of tissue reduction and the amount of energy delivered.

Holmium-YAG laser enucleation of the prostate is very effective in treating large glands, with an efficacy comparable to open prostatectomy [23–28]. However, many authorities consider that the technique is difficult to learn [29]. PVP is easier to use, although a systematic evaluation of outcome and safety profiles during the early experience is still needed. Laparoscopic transvesical or transcapsular prostatectomy for BPH is gaining popularity, but has not so far been shown to have lower complication rates or hospital stay [30,31].

More recently the 120 W GreenLight laser vaporization technique, the high-performance system has been introduced and is gaining popularity. The initial results with this technique at our institution are exciting (unpublished). The high-performance system involves a 600-µm fibre emitting laser energy similar to the 80 W systems at 70° and at 532 nm. The advantages include better vaporization than with the earlier 80-W systems, and easier switching between vaporization and coagulation modes (20 W), as and when needed. Further evaluation of this technique is needed, comparing the outcomes against existing laser systems.

In conclusion, with minimal intraoperative irrigant absorption and rapid tissue ablation, the 80-W KTP laser is an interesting tool for ablating very large prostates, otherwise possibly requiring open prostatectomy. While the total amount of tissue removed is likely to be less than with open prostatectomy, it is clear that the safety factors are outstanding, giving an excellent functional result, with acceptable medium-term outcomes. In particular, the excellent haemostatic and rapid tissue ablation facilitates minimal morbidity and rapid discharge of patients from hospital, adding quality of life to the patient whilst reducing the demand for hospital beds. The GreenLight PVP is a safe and effective method of treating BOO caused by very large prostates.


None declared.


This body of work and research contributes to the growing consensus that PVP with the 532 nm high-power laser system is a viable alternative for the surgical treatment of BPH, but especially in those for whom surgical options are a high risk. This report shows that PVP can be done in patients with large prostates, at high surgical risk and who need anticoagulant therapy. These findings are consistent with many from those who have published and presented reports on this topic.

While there is no clear consensus on what threshold constitutes a ‘large’ prostate, the decision between an open prostatectomy or TURP is related to the risks of open pelvic surgery (which include not only those potential complications that can be life-threatening, e.g. deep vein thrombosis, risk of pulmonary embolus and complications related to haemodynamic instability due to bleeding in high-risk cardiovascular patients) vs the risk of a TURP of >40 min, because such a TURP with a hyponatraemic solution carries a significantly greater risk of bleeding, requiring transfusion, and dilutional hyponatraemia, which are significant contributors to cardiovascular complications. Also, transurethral equipment might not be sufficiently long to manage a large prostate. Thus, the decision for open prostatectomy vs TURP generally rests on the ‘comfort zone’ and skill of the surgeon in charge.

Notably the risk of ureteric injury is not surprisingly higher with this ‘King’s spiral’ technique, especially with large intravesical middle lobes, as ‘spiralling’ at the bladder neck area and especially over the middle lobe can easily injure the ureteric orifice if it is not visualized properly. Also, this technique appears to be a variation of the ‘Malek’ technique [1]. This concern has been addressed by emphasising the maintenance of close contact at the bladder neck and carefully monitoring the aiming beam direction before vaporization. Notably, another technique that addresses the management of large glands and the issue of avoiding the ureteric orifice in men with large intravesical middle lobes is the ‘PVP incision technique’, which is described in an online video available via the AUA web site [2]. Basically, a vaporization incision groove is created at the 6 o’clock position on the middle lobe, between the ureteric orifices, to split the middle lobe down to the bladder neck/trigone level, and at the 7 o’clock and 5 o’clock positions well lateral to the ureteric orifice. Once these incisions are made, laser vaporization can then be continued away from the ureteric orifice, with visual identification of the orifice.

Alexis E. Te, Weill Medical College of Cornell University, New York, USA

1 Malek RS, Kuntzman RS, Barrett DM. High power potassium-titanyl-phosphate laser vaporization prostatectomy. J Urol 2000; 163: 1730–3

2 Sandhu JS, Te AE. Photoselective vaporization of the prostate - the vaporization incision technique for large volume prostates. J Urol 2005; 173: 366. Available from the AUA video/DVD Library #SV050607, at