Transurethral ultrasound-guided laser-induced prostatectomy (TULIP procedure): a canine prostate feasibility study

Lasers in the surgical treatment of canine prostatic neoplasia and selected tumours of the male reproductive system

Light-based technologies are applied in various fields of medicine: for example optical diagnostics, light-activated therapy and surgery. Although light-based surgical procedures had hardly been a novelty, the revolutionizing moment for surgery came with the first use of light to cut tissue. Nowadays, surgical lasers are routinely used across numerous medical specialties, including gynaecology and urology. They are a part of the surgical treatment of benign prostatic hyperplasia, prostate carcinoma, penis carcinoma, genital skin lesions and orchidectomy. While in human urology lasers continue to establish their position as one of the standard surgical tools, veterinary patients are rarely treated with what here is still considered a technical innovation. However, through research on laser treatment of the prostate hyperplasia conducted on a canine model, veterinary medicine has gained a massive portion of data. It may prove beneficial for our clinical patients. In this review, we introduce the very principles of laser surgery as well as its current and future applications in oncologic surgery of the canine prostate gland and the male reproductive system.

Thermal ablation of prostate diseases: advantages and limitations

Both benign and malignant conditions affecting prostate gland are very common in elderly men. However, the conventional treatment of these conditions can be associated with significant side effects and complications, and less invasive treatment alternative has been always searched for. Because of the anatomical location and easy accessibility of prostate, many newer treatment modalities using thermal ablation have been applied to the organ. These include not only heating of the pathological tissue but also freezing. Some of such treatment techniques have shown to be effective and safe and been clinically used widely. In this review article, various tissue ablation techniques using temperature change applied to prostate gland are covered. Each procedure's advantages and disadvantages are compared and discussed.

Comparative study of transurethral laser prostatectomy versus transurethral electroresection for benign prostatic hyperplasia

BACKGROUND

Transurethral resection of the prostate (TURP) is the gold standard treatment for benign prostatic hyperplasia (BPH). Recently, less invasive transurethral laser prostatectomy, such as visual laser ablation (VLAP) or interstitial laser coagulation (ILCP), have been developed. Herein, we investigated the efficacy of VLAP and ILCP compared to TURP.

METHODS

A total of 80 patients with BPH were treated: 20 patients by VLAP, 30 patients by ILCP and 30 patients by TURP. All patients were followed up for 12 months after their operations. Treatment outcomes were evaluated by four different criteria: (i) the International Prostatic Symptom Score (I-PSS), (ii) the maximum flow rate (Qmax), (iii) postvoided residual urine volume before treatment and one, three, six and 12 months after treatment, and (iv) prostatic volume before operation and three and six months postoperatively.

RESULTS

The I-PSS, Qmax and residual urine volume were significantly improved compared to baseline levels and the improvement continued for 12 months in the three groups: for I-PSS (P<0.001 in the VLAP group and P<0.0001 in the ILCP and TURP groups), Qmax (P<0.001 in the VLAP and ILCP groups, and P<0.0001 in the TURP group), residual urine volume (P<0.01 in the VLAP group and P<0.0001 in the ILCP and TURP groups). Significant reduction of the prostatic volume was recorded only in the ILCP and TURP groups (P<0.001).

CONCLUSION

Visual laser ablation and ILCP can be good alternative treatments for BPH. Visual laser ablation provides good outcomes in patients with small-sized BPH and with risk factors such as heart disease or anticoagulation therapy.

The "Wedge" resection device for electrosurgical transurethral prostatectomy

The "Wedge" (Microvasive, Natick MA) is a new electroresection device for transurethral prostatectomy (TURP) using the standard resectoscope. The design, which is broader than the standard loop and thickens from front to back, results in better hemostasis when used at 275 to 300 W because of its ability to cut and coagulate tissue simultaneously. In the canine model, histologic examination demonstrated a 2-mm zone of coagulation around the chips and in the resection bed; this response was not observed in the specimens resected by the standard tungsten loop. No adjacent tissue damage was found with either the Wedge or the loop, and the temperatures recorded at the capsule rose only 4 degrees C regardless of the device used. In the 65 patients treated, the average hematocrit drop on postoperative Day 1 was 3.0%, and serum sodium was unchanged. One year postoperatively, the peak flow rate had increased by 101%, and the AUA Symptom Score was 6.1. The only surgical complication was urethral strictures (3%) necessitating incision. Most striking was the increased case of resection attributable to improved intraoperative vision. The data suggest that Wedge TURP is as safe and efficacious as standard loop TURP. The surgical field is markedly improved and clear because of intraoperative hemostasis. A TURP can be performed with a view toward minimizing patient morbidity and increasing surgical ease.

Transurethral ultrasound-guided laser-induced prostatectomy: a critical evaluation

We evaluated 38 patients with a follow-up of 30 months after transurethral ultrasound-guided laser-induced prostatectomy (TULIP) for benign prostatic hyperplasia. The mean symptom score decreased by 54%, and peak urinary flow increased by 112%. For the entire series, 43.6% of the patients had an improved symptom score and 41% better urinary flow, but only 28.2% had improvement in both. Six patients (16%) required reoperation, two underwent a radical prostatectomy, and one patient presented total urinary incontinence. Also, 19% presented postoperative impotence, and 47% presented retrograde ejaculation. Although one third of the patients are improved with the TULIP procedure, the rate of complications is significantly higher than for TURP, which remains the most effective treatment of obstructive BPH.

Theoretical analysis of transurethral laser-induced thermo-therapy for treatment of benign prostatic hyperplasia. Evaluation of a water-cooled applicator

A mathematical model for predicting the temperature rise in transurethral laser-induced thermo-therapy for benign prostatic hyperplasia was developed. In the model an optical line source emitting light from an Nd:YAG laser isotropically was placed in the urethra. Water cooling of the urethral epithelium was modelled using a two-tube system. The relationship between the difference in outlet and inlet water temperatures and the highest tissue temperature level reached was theoretically investigated. It was found that the water temperature difference was linearly dependent on the steady-state maximum tissue temperature. The theoretical calculations suggest that the water-cooled applicator can be used to measure the maximum tissue temperature. With temperature control, the prostatic tissue temperature can be prevented from exceeding the boiling point of water, excluding tissue carbonization. The model was also used to evaluate the influence of a number of different parameters on the damaged tissue volume. Increasing the urethral lumen radius by a factor of two by means of inserting different sized tubes was found to augment the tissue volume raised to therapeutic temperatures by up to 50%. The calculations showed that cooling of the urethral epithelium can result in an increase in the damaged volume by 80% as compared to not applying any cooling. The temperature of the cooling water was found to influence the tissue temperature only to a small extent.

Dosimetry studies utilizing the urolase right-angle firing neodymium:YAG laser fiber in the human prostate

BACKGROUND AND OBJECTIVE

Until recently, little or no objective data have been available to support either the choice of power setting or the timing of laser applications to achieve optimal tissue ablation in the human prostate. The objective of this study was to define quantitative dosimetry curves for the Urolase right angle laser fiber in human prostates. STUDY DESIGN MATERIALS AND METHODS: Transurethral Neodymium:YAG laser application was performed with the Urolase right-angle laser fiber in adult human prostates prior to planned radical surgery. Depth and volume of prostatic tissue coagulation for single, continuous laser applications were measured at variable power settings from 20 to 60 watts while holding total energy delivery constant. Then, holding the power setting constant at 40 watts, the extent of tissue coagulation was measured for variable treatment times from 60 to 120 seconds.

RESULTS

Peak tissue coagulation was observed at 40 watts up to a maximum of 14 mm tissue penetration and 4.23 cc volume coagulated following a single spot laser application. The mean depth of tissue coagulation at 40 watts power setting was 13.5 mm, with a mean volume of tissue coagulation of 3.68 cc. The mean depth of tissue penetration at 40 watts was more than 25% greater than that observed at 60 watts, and the mean volume of tissue coagulation was 190% greater than that observed at 60 watts. As treatment time was increased from 60 to 90 seconds, extent of tissue coagulation increased significantly. However, beyond 90 seconds continuous laser application at 40 watts, a plateau in tissue effects was observed, with minimal increase in tissue coagulation between 90 and 120 seconds. Histologic examination of prostates removed acutely showed heat-induced damage to both stromal and glandular epithelial elements in laser-treated areas. At 1 year, the prostatic urethra was lined with a normal transitional epithelium, and mild periurethral fibrosis with focal squamous metaplasia was seen.

CONCLUSION

Using the Urolase right-angle laser fiber, this study suggests that 40 watts power setting and 90 seconds continuous application time with a Neodymium:YAG laser source represent optimal treatment parameters to maximize prostatic tissue coagulation.

Clinical studies on advantages and safety of visual laser ablation for patients with benign prostatic hyperplasia

Since 1992, we have been performing VLAP using a right-angle laser delivery system (Urolase) for BPH patients with significant underlying nonurological diseases such as diabetes mellitus, cardiovascular, pulmonary, and malignant diseases. Sufficient clinical results have been obtained without major complications during short-term and long-term observation. In this study, we discuss the clinical advantages and safety of VLAP, compared with TURP, through analysis of the clinical procedure for VLAP for patients treated with anticoagulant agents such as warfarin. In our study of 40 patients, 8 patients were treated with anticoagulants for cardiovascular disease. During the procedure and after the operation, no significant complications were encountered except for transient postoperative bleeding. The 8 patients who received simultaneous anticoagulant therapy also underwent TURP to draw a comparison. The time taken for the procedure and the volume of the blood loss were significantly reduced by VLAP. The hemostatic nature of YAG laser energy seems to result in a technical improvement over conventional I URP for patients undergoing anticoagulant therapy.

Electrosurgical vaporization of the prostate in the canine model

OBJECTIVES

To investigate the histopathologic changes and heating patterns caused by electrosurgical vaporization of the prostate in the living canine model.

METHODS

Prostate electrosurgical vaporization was undertaken in the canine model. Temperatures within and near the prostate and of the irrigation fluid were measured during a single pass and during the creation of a vaporized cavity. The prostate and adjacent tissues were examined by gross and microscopic pathology.

RESULTS

Coagulation occurred deep to the vaporization zone for 1.38 to 1.44 mm for a single pass of the rolling cylinder and up to 2.52 mm for multiple passes. Thermometry revealed temperature increases of only 4 degrees C 5 mm away from the vaporization site. The largest temperature increases were found in the irrigation fluid as it passed through the prostatic fossa. Microscopic pathology revealed no damage to adjacent tissues.

CONCLUSIONS

Electrosurgical vaporization creates minimal deep heating and coagulation beyond the vaporized cavity. The majority of the heat is removed by the irrigation fluid.

Ultrasonographic and pathologic changes in the prostate of patients with benign prostatic hyperplasia after transurethral balloon laser therapy

Twenty-seven patients with benign prostatic hyperplasia (BPH) were treated with a transurethral flexible laser balloon (PROSTALASE) under ultrasound guidance. Three months after treatment, 22 (82%) of the patients showed a 50% or greater decrease in the AUA Symptom Score. The average uroflow rate, peak uroflow rate, and postvoiding residual urine volume also showed significant improvement. Ultrasonography showed that the prostatic volume had decreased by 17% (8%-37%). Also, a circular hyperechoic zone about 3 cm in diameter was noted around the prostatic urethra. The prostatic tissue in the hyperechoic zone was sampled by transperineal needle biopsy under transrectal ultrasound guidance, and histopathologic examination showed degenerative necrosis. The necrotic tissue was gradually absorbed, resulting in prostatic shrinkage at around the third month. These results suggest that clinical improvement, both subjective and objective, is brought about by this therapy.

Laserterapia della IPB

TURP is performed in 80% of cases of benign prostatic hypertrophy (BPH), but one of the alternative methods, which uses the photocoagulating energy of the laser beam and in particular the Nd-Yag, seems to be very promising. Used in prostates with a suitable weight (< 40 g) and in particular in high-risk patients with myocardiopathies and/or coagulative troubles, this source of energy, through fibres at right angles or in contact or interstitial, permits the photocoagulation or vaporisation of the prostatic tissue. Association of this technique with the usual TURP has been suggested in heavier prostates, for a quick return to spontaneous micturition. The absence of bleeding, retrograde ejaculation and more serious complications, plus the reduced time of hospitalisation make this a safe technique in selected cases.

A urodynamic study of laser ablation of the prostate and a comparison of techniques

OBJECTIVE

To evaluate the effect of laser ablation of the prostate on symptomatic and urodynamic parameters and to compare laser delivery systems.

PATIENTS AND METHODS

The study comprised 81 patients of whom 79 were waiting for transurethral resection of the prostate (TURP) and two who presented in acute urinary retention. The 79 patients (median age 65 years, range 45-82) underwent pre-operative urodynamics and all patients completed American Urological Association (AUA) symptom score questionnaires before surgery. Visually-guided laser ablation of the prostate (VLAP) was performed and the urodynamics and symptom scores were repeated 3 months later.

RESULTS

The improvements in symptom scores and flow rates were statistically significant and comparable with other published data. There were also significant improvements in voiding pressure. There were no significant differences between the various laser fibres used. There were few complications.

CONCLUSION

The effectiveness of VLAP in improving symptoms and flow rates in patients with benign prostatic hyperplasia (BPH) is confirmed. The procedure also reduced voiding pressure, confirming the relief of bladder outflow tract obstruction. VLAP is confirmed as a safe and effective treatment for BPH. Continued follow-up is needed to determine the long-term effects.

A prospective randomized comparison of transurethral resection to visual laser ablation of the prostate for the treatment of benign prostatic hyperplasia

OBJECTIVES

Transurethral resection of the prostate (TURP) represents the accepted standard of surgical therapy for the management of symptomatic bladder outlet obstruction due to benign prostatic hyperplasia (BPH). However, this is a major operative procedure associated with significant perioperative morbidity. Visual laser ablation of the prostate (VLAP) utilizing a neodymium:yttrium-aluminum-garnet laser represents a new technologic approach to the surgical management of BPH. We compared the relative safety and efficacy of these two surgical approaches in a prospective, randomized trial.

METHODS

At 6 investigational sites in the United States, 115 men with symptomatic BPH more than 50 years of age and not in retention, were randomly assigned to undergo either TURP (59 patients) of VLAP (56 patients). VLAP patients received a mean of 10,200 J of energy delivered in a mean of 5.5 intraprostate laser applications. At preoperative baseline, 3 months, 6 months, and 1 year postoperatively, all patients underwent clinical evaluations, including ultrasonic prostatic volume determination, standardized American Urological Association (AUA)-6 symptom score, peak urine flow, postvoid residual urine volume, and quality-of-life assessment.

RESULTS

Compared to TURP, the VLAP procedure required less time (23.4 versus 45.2 minutes; P < 0.01) and shorter hospitalization (1.8 versus 3.1 days, P < 0.01). VLAP was associated with a significantly lower rate of serious treatment-related complications compared to TURP (10.7% versus 35.6%; P < 0.01). Only One (2.2%) patient undergoing VLAP experienced a greater than 2.2 g/dL decrease in hemoglobin compared to 40% of TURP patients (P = 0.01). No patient in the VLAP group required blood transfusion compared with 3.4% of those undergoing TURP. Of the 115 patients, clinical outcomes measured at 1 year showed a mean improvement in AUA-6 symptom scores of -9.0 for VLAP compared with -13.3 for TURP (P < 0.04), mean increase in peak urinary flow rate of 5.3 cc/s for VLAP compared with 7.0 cc/s for TURP (P = 0.27), and mean decrease in postvoid residual urine volume of -55.4 cc for VLAP compared with -138.8 cc for TURP (P < 0.01). At 1 year, 78.2% of patients undergoing VLAP indicated that their quality of life was improved compared with 93.0% of patients undergoing TURP (P = 0.03). When compared with TURP, treatment of BPH with VLAP is associated with less hemoglobin decrease, a lower likelihood of serious complication, and requires less procedure time and a shorter hospital stay. Through a 1-year follow-up, VLAP produced significant improvement over baseline in objective and subjective outcome measures. However, for 1-year improvement in AUA-6 symptom score, postvoid residual urine volume, and quality of life, VLAP was less effective than TURP.

CONCLUSIONS

In this initial study in the United States, with relatively low-energy laser applications, VLAP did not result in as complete a removal of prostatic tissue as did TURP. Considering the lower morbidity, shorter procedure and hospitalization times, and the degree of effectiveness that was achieved even at the low-energy doses used in this study, VLAP appears to be a viable and safe alternative to standard TURP.

Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a pathologic disorder that develops in response to the action of dihydrotestosterone on the aging prostate and to changes in stromal and epithelial cells in this exocrine gland. The current therapies for this disorder are chosen after other causes for irritative and obstructive symptoms have been excluded and the status of the urinary tract has been assessed. This evaluation includes a detailed medical history, a thorough genitourinary and neurological examination, assessment of serum prostate specific antigen and creatinine levels, as well as a urinalysis. A urodynamic evaluation consisting of a combined pressure-flow study is required if the diagnosis of obstruction is to be made. Patients with minimal symptoms and normal test results require no therapy. Mild to moderate symptoms can be controlled, at least temporarily, with alpha-adrenergic blockers such as terazosin or doxazosin. A subset of BPH patients with obstructive symptoms respond to the 5 alpha-reductase inhibitor finasteride. Early results with minimally invasive treatments such as laser prostatectomies, hyperthermia, and ultrasonic and radiofrequency ablation appear encouraging for those with moderate symptoms of prostatism. Severe symptoms, urinary retention, gross hematuria, recurrent urinary tract infections, bladder calculi, and hydronephrosis or renal insufficiency warrant transurethral incision, resection, vaporization, or open prostatectomy (for very large neoplasms). Although the morbidities of these latter surgical therapies are not insignificant, these treatments offer the best and most durable results for relief of obstruction and amelioration of symptoms.

Use of bare fiber with siderfiring Albarran bridge in laser therapy of the prostate

Laser coagulation of the prostate has been performed using a bare fiber passed through a sidefiring Albarran bridge containing a distal gold-plated reflector with a deflecting mechanism. The system and the fiber can be used for several dozen treatments. Transurethral laser coagulation with the new Albarran bridge and the noncontact Nd:YAG laser was performed on 45 patients for obstructive symptoms caused by benign prostatic hyperplasia. The dosimetry was 1000 J per 1 cc of prostatic tissue at 60 W for 60 seconds. Successful results were obtained in 38 patients (85%). A significant reduction in obstructive symptoms from a mean AUA-6 Symptom Score of 21.2 preoperatively to 9.1 at 3 months and 7.6 at 6 months was associated with an increase in the peak urine flow rate from 6.1 mL/sec preoperatively to 13.1 mL/sec at 3 months and 15.7 mL/sec at 6 months. The residual urine volume averaged 190 mL preoperatively and 35 mL at 6 months. Transurethral laser coagulation of the prostate represents a useful alternative to transurethral resection, especially in the high-risk patient with an enlarged median lobe or a small prostate. The treatment is bloodless and, with the aid of the modified Albarran bridge, can be performed with a standard urologic Nd:YAG laser. The new Albarran bridge also can reduce the cost of laser treatment.

Laser coagulation prostatectomy: evolution of clinical practice and treatment parameters

Laser coagulation prostatectomy has evolved into an accepted option for the management of bladder outlet obstruction secondary to benign prostatic hyperplasia. Clinical results document the safety and efficacy of this operation. Rapidly expanding clinical experience and basic research efforts in recent years have provided a scientific foundation and an improved qualitative understanding of the laser-tissue interactions during Nd:YAG laser coagulation of the prostate. Today, truly quantitative laser dosimetry is becoming available to guide the operative approaches to laser prostatectomy with the increasing variety of Nd:YAG delivery systems. The development of laser coagulation prostatectomy is traced to the present, and accumulated clinical experience and laboratory data are incorporated into a rational approach to operative and perioperative patient management utilizing this technology.

Prostatic aperture resulting from visual laser ablation: classification system based on follow-up endoscopy

To study the evolving prostatic aperture created by visual laser ablation (VLAP), we performed 38 video-endoscopies in 24 men with prostatism at various intervals 2 weeks to 1 year after treatment. Complete healing was generally observed within 3 to 4 months, never before 6 weeks; and in some patients, tissue sloughing was still apparent beyond 6 months. By review of the cystoscopic findings and video hard copies, three independent observers classified the healed prostatic apertures with great uniformity into one of four categories: (I) minimal change (lateral lobes still meet in midline throughout gland length) (N = 3); (II) minor aperture (opening less than 50% of cystoscopic field over less than 50% of gland length) (N = 5); (III) major aperture (opening more than 50% of cystoscopic field over more than 50% of gland length) (N = 11); and (IV) full ablation (nearly complete replacement of lobar configuration with a general concavity) (N = 5). Clinical outcomes (symptom scores, uroflow rates) matched with follow-up cystoscopic categories but not with any other readily identifiable measures. The four-category system proved to be simple, reproducible, and clinically relevant. If a standardized tissue aperture is the ultimate aim of new methods to ablate the prostate, the proposed system for classifying the aperture could have a considerable future application.

Transurethral balloon laser thermotherapy for symptomatic benign prostatic hyperplasia: preliminary clinical results

Between April 1993 and May 1994, 66 patients were treated with transurethral balloon laser thermotherapy (TUBAL-T) for the relief of bladder outlet obstruction secondary to benign prostatic hyperplasia. TUBAL-T, with a urethral cooling system, employs a balloon catheter and irradiating laser through 360 degrees to produce deep coagulation and necrosis of the prostatic tissue while preserving the urethral mucosa. The procedure was implemented under local topical anesthesia. Baseline AUA Symptom Scores, peak uroflow rates, postvoiding residual urine volumes (PVR), and prostatic volumes were measured before and at 1, 3, 6, and 12 months after treatment. The mean symptom score decreased from 18.8 preoperatively to 9.8, 6.9, 7.4, and 4.8 at 1, 3, 6, and 12 months, respectively. The mean peak uroflow rate increased from 6.4 mL/sec to 9.1, 11.2, 10.1, and 10.4 mL/sec at 1, 3, 6, and 12 months, respectively. As for the mean PVR, statistically significant reductions were clearly observed at 3 and 6 months after treatment. However, at 1 and 12 months, the difference was not statistically significant. In follow-up for as long as 12 months after the procedure, 23 of 26 patients (88%) showed an improvement of 50% or more in the AUA Symptom Scores. Of 20 available patients, 12 (60%) showed an improvement of 50% or higher in the peak uroflow rates, and 10 (50%) showed an improvement of 50% or higher in PVR. The mean prostatic volume reductions at 3, 6, and 9 months were 12%, 16%, and 14%, respectively. The serum prostate specific antigen concentration increased to four times the baseline concentration on the 7th day.(ABSTRACT TRUNCATED AT 250 WORDS)

Complications of laser prostatectomy

The appeal of laser therapy is rooted in its absence of complications relative to the gold standard of transurethral electroresection. As in any evaluation of a new medical intervention, efficacy must be weighed against the degree of complications that accompany it. Although there has been a relative paucity of literature specifically addressing the safety of this new modality, several studies are presented testifying to the clinical efficacy and relative absence of complications of laser prostatectomy.

Insight into mechanism of neodymium: yttrium-aluminum-garnet laser prostatectomy utilizing the high-power contact-free beam technique

OBJECTIVES

The objective of this study was to define the actual mechanism of neodymium: yttrium-aluminum-garnet (Nd:YAG) laser prostatectomy achieved with the previously described contact-free beam technique using the Ultraline delivery system at high-power settings.

METHODS

Transurethral Nd:YAG laser application was performed with the Ultraline side-firing laser fiber in canine and human prostates. Total or radical prostatectomy was performed after laser treatment to examine and measure laser tissue effects produced using the contact-free beam technique.

RESULTS

Minimal actual tissue evaporation or vaporization was noted in either the canine or human prostate using this technique. The extent of tissue vaporization achieved was probably insufficient to produce clinically significant voiding outcomes acutely or chronically. However, this technique, using the Nd:YAG laser, produced excellent tissue coagulation and necrosis, similar to other laser delivery systems and reports dealing with laser coagulation prostatectomy.

CONCLUSIONS

The primary mechanism accounting for therapeutic efficacy of the contact-free beam technique for Nd:YAG laser prostatectomy utilizing the Ultraline delivery system at high-power settings appears to be tissue coagulation with subsequent necrosis and slough, rather than tissue vaporization. This is consistent with the known tissue effects of the Nd:YAG laser wavelength in other systems.

Laser prostatectomy: initial experience and urodynamic follow-up

OBJECTIVES

An evolving technology for the treatment of bladder outlet obstruction due to benign prostatic hyperplasia (BPH) is the use of the side-firing neodymium: yttrium-aluminum-garnet (Nd:YAG) laser to achieve prostatic tissue ablation. The purpose of this study was to determine the short-term efficacy of this procedure in both an objective and subjective manner.

METHODS

We examined this technique by carefully evaluating our first 25 men undergoing the procedure. Each patient was subjected to careful symptom score analysis using the American Urological Association symptom index and multichannel urodynamics, including pressure-flow studies both preoperatively and at 3 months postoperatively.

RESULTS

At the 3-month follow-up, symptom scores improved from a preoperative mean of 11.4 to 7.2 and the mean maximum flow rate improved from 6.1 to 14.5 cc/s. These are both significant at P < 0.001. Statistically similar improvement was seen in detrusor pressure at opening and at maximum flow. Eighty percent of the men studied had at least a 50% reduction in symptom score and a 50% improvement in flow rate.

CONCLUSIONS

We conclude that laser prostatectomy is a promising minimally invasive treatment for bladder outlet obstruction secondary to BPH and deserves further evaluation at longer terms of follow-up.

Transurethral ultrasound-guided laser-induced prostatectomy: clinical outcome and data analysis

OBJECTIVES

To analyze efficacy and side effects of the transurethral ultrasound-guided laser-induced prostatectomy (TULIP) procedure for the treatment of bladder outlet obstruction due to benign prostatic hyperplasia (BPH). Based on the results obtained so far, the influence of preoperative and intraoperative parameters on clinical outcome is analyzed.

METHODS

Between May 1991 and March 1994, 89 men with symptomatic and obstructive BPH underwent a TULIP procedure and were followed after 3 and 6 weeks, and 3, 6, and 12 months postoperatively.

RESULTS

On average, mean urinary peak flow increased from 7 to 15 mL/s, postvoidal residual urine decreased from 215 to 40 mL and symptoms (assessed by modified Boyarsky score) decreased from 17 to 5 at 12 months after TULIP: In about half of the patients peak flow increased to more than 20 mL/s on average, and approximately 85% of all men reported that their symptoms improved on average 80% during this time. Because of insufficient micturition, 7 patients subsequently underwent conventional transurethral resection of the prostate (TURP) and 1 had an open prostatectomy. Either partial or complete retrograde ejaculation was reported by 13 of 58 sexually active men. No blood transfusion was required and no post-transurethral resection syndrome occurred in any case. Analyses of preoperative and intraoperative parameters and clinical outcome with respect to prostate volume, urinary retention, type of BPH enlargement, sleeve size, and good and poor responders did not reveal any significant influence of any factor. There is, however, a trend toward a lower laser energy delivered in patients who failed or may be considered to be poor responders.

CONCLUSIONS

In this unselected group of patients with BPH, who otherwise would have been TURP candidates, the TULIP procedure demonstrated the efficacy of this technique to relieve bladder outlet obstruction. Compared with TURP, the TULIP procedure proved to be advantageous in regard to less blood loss and rate of retrograde ejaculation. In addition, TULIP can be performed under analgesic sedation, which is especially advantageous in high-risk patients. Disadvantages, however, are that it takes a considerably longer time to obtain substantial improvements in subjective and objective symptoms and there are more irritative symptoms in the early postoperative phase.

Neodymium: yttrium-aluminum-garnet laser dosimetry for the prolase II side-firing delivery system in the human prostate

OBJECTIVES

The objective of this study was to define optimal treatment parameters and quantitative dosimetry for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser coagulation prostatectomy utilizing the ProLase II side-firing laser delivery system.

METHODS

Transurethral Nd:YAG laser application was performed with the ProLase II side-firing laser fiber in adult human prostates prior to planned radical prostatectomy. Depth and volume of prostatic tissue coagulation for single, continuous laser applications were measured at variable power settings from 40 to 80 W, while holding total energy delivery constant. Holding the power setting constant, the extent of tissue coagulation was similarly measured for variable treatment times from 45 to 90 seconds.

RESULTS

Peak tissue coagulation for the ProLase II was observed at 60 W--up to a maximum of 13 mm tissue penetration and 3.92 cc volume coagulation following a single spot laser application. The mean depth of tissue coagulation at 60 W power setting was 12.7 mm, with a mean volume of tissue coagulation of 3.07 cc. Holding the power setting constant at 60 W, and increasing treatment time from 45 to 60 seconds, the extent to tissue coagulation increased significantly. However, beyond 60 seconds continuous laser application at 60 W, a plateau in tissue effects was observed, with minimal increase in tissue coagulation between 60 and 90 seconds.

CONCLUSIONS

Using the ProLase II side-firing laser fiber, 60-second Nd:YAG spot laser applications at 60 W power setting represent optimal treatment parameters. The quantitative dosimetry curves produced for the ProLase II fiber are compared with prior dosimetry studies with the Urolase delivery system.

Lasers in the treatment of benign prostatic hyperplasia

Laser treatment of men with BPH remains in its infancy. To date, a large number of techniques and devices have been developed and investigated to varying degrees. Each laser system that is utilized in a unique fashion must be evaluated individually, since tissue effects may vary significantly with minor changes in technique or technology. Overall, it appears that the majority of men treated by laser prostatectomy experience objective and subjective improvement with short-term follow-up. In most cases, further direct comparisons with TURP with longer follow-up are needed to assess adequately the relative efficacy and morbidity of laser therapy. Although early results are promising and technologic advances are likely to improve further the results seen with laser treatment of men with BPH, it may be premature to relegate TURP to the history books.

Lasers in urology

Ever since Mulvany first described use of Ruby laser for lithotripsy, urologists have been exploiting every possible application of this technology. Laser lithotripsy in the 1980s and now laser prostatectomy in the 1990s have dominated laser usage in urology. Applications of lasers for superficial lesions (e.g., condylomata acuminata and carcinoma of penis) have found an established role. Interests in laser welding, photodynamic therapy and fluorescence continues to grow and evolve. The laser industry at the same time is striving to provide more efficient lasers. High power lasers (Holmium:YAG, KTP:YAG) and laser machines combining double wavelengths (Nd:YAG and KTP, Ho: YAG and Nd:YAG) are commercially available. Diode lasers with their portability and reliability qualities can now provide high output powers in various wavelengths. Here, we have reviewed different lasers, laser tissue interaction and clinical laser applications relevent to urology.

Transurethral balloon laser prostatectomy in the canine: medium-term, follow-up results

BACKGROUND AND OBJECTIVE

To demonstrate surgical complications in transurethral balloon laser prostatectomy by medium-term, follow-up observation.

STUDY DESIGN/MATERIALS AND METHODS

Three dogs were treated with transurethral laser irradiation using 15 watts for 20 minutes at 60 degrees C at a 5 mm depth of the prostate, one dog was for 5 minutes with same parameters, and one dog was with only laser balloon probe as a control. All animals were followed for 24 weeks.

RESULTS

A large cavity in the prostatic urethra was formed in laser-treated animals 4 weeks later, whereas the cavity in the balloon-treated animals was not shown. Cavity volume did not significantly change for 6 months, and there was no bladder neck stricture or urethral stenosis observed in any case. An increase in collagen fibers in the periurethral tissue was barely observed by Mallory staining.

CONCLUSION

The risk of bladder neck stricture and urethral stenosis was estimated to be low for transurethral balloon laser prostatectomy.

Transurethral Nd:YAG laser prostatectomy with a laterally firing fiber: local effects on tissue associated with erectile dysfunction

BACKGROUND AND OBJECTIVES

Transurethral laser prostatectomy is anticipated to become a recognized alternative to conventional transurethral resection of the prostate. However, the effects of this procedure on the nerves of the pelvic plexus and erectile dysfunction remain unaddressed. The objective of this study was to evaluate the effects of laser energy on extent of prostatic damage as well as injury to periprostatic cavernosal nerves and erectile dysfunction in a canine model.

STUDY DESIGN/MATERIALS AND METHODS

Six adult male mongrel dogs underwent transurethral laser prostatectomy at 30 (n = 3) and 40 (n = 3) watt power settings. Total laser energy delivered varied between 6,000 and 13,800 joules. Erectile function was evaluated by pelvic nerve stimulation at 2, 4, and 8 weeks. Animals were then sacrificed to assess histopathology of the prostate at each time point.

RESULTS

Histopathologic changes were noted in the prostate in a dose-dependent manner and did not vary with different laser power settings. In dogs that received approximately 10,000 J, substantial prostate ablation confined within the capsule was achieved in every prostate gland. Adequate erectile responses were noted in five of six animals; all received < 10,000 J. In one animal that received a total dose of 13,800 J, an erectile response was not obtained, and histology revealed both prostatic capsule perforation in close proximity to the cavernous nerves and thermal neural damage.

CONCLUSIONS

We conclude that cavernous nerve damage may result from excessive doses of laser energy during transurethral laser treatment of the prostate gland. In canines, the upper limit for periprostatic injury is between 10 and 14,000 joules.

Histopathological changes in human prostatic adenoma following neodymium:YAG laser ablation therapy

Transurethral laser ablation of the prostate is a procedure currently under evaluation as an alternative to transurethral resection of the prostate in the management of benign prostatic hyperplasia. Removal of prostatic tissue by endoscopic resection or open surgical techniques from 7 patients in whom prostatic laser ablation was previously attempted offered an opportunity to evaluate the sequential effects of such energy upon the human prostate at varying intervals after treatment. A progressive inflammatory and necrotic response, initially akin to that demonstrated after a thermal burn, together with evolving vascular changes within the residual viable prostatic tissue were demonstrated. Our study demonstrates the changes in the human prostate whereby neodymium:YAG laser energy causes a deep coagulative necrosis and arterial thrombosis in the prostatic adenoma. These changes differ significantly from those noted in canine studies. A slower cavitation effect is observed in the human compared with the canine, and this finding mirrors the continuing clinical improvement in voiding parameters with time.

Endoscopic and ultrasonographic observation of the canine prostate after transurethral balloon laser therapy (PROSTALASE)

We investigated the healing process and changes in the canine prostate after transurethral balloon-equipped laser (PROSTALASE) prostatectomy using both endoscopy and transrectal ultrasonography (TRUS). On TRUS, the prostate volume was significantly increased (123%) just after irradiation, decreasing to 106% at 1 week. Cavity formation was observed in the prostate 1 week after irradiation, and the median volume was 1.5 cm3 at 4 weeks. A TRUS study performed immediately after irradiation revealed a 1- to 2-mm deep hyperechoic lesion around the urethra. Urethrocystoscopy disclosed red and markedly edematous mucosa of the prostatic urethra, but no hemorrhage. The hyperechoic mass was also observed in the cavity on TRUS images 1 week later. Urethrocystoscopy disclosed abundant necrotic tissue within the cavity, and reddish granulomatous sections were observed on a portion of the cavity surface. At 4 weeks, the hyperechoic mass in the cavity was no longer observed on TRUS images. The prostate parenchyma was thin but uniformly isoechoic. At urethrocystoscopy, a smooth surface without redness and with the small craters, which were histologically identified as the duct openings of the prostate gland, were observed.

Treatment of benign prostatic hyperplasia by transurethral ultrasound-guided laser-induced prostatectomy (TULIP): effects on urodynamic parameters and symptoms

OBJECTIVES

This prospective study was undertaken to evaluate the effects of transurethral ultrasound-guided laser-induced prostatectomy (TULIP) on urodynamic, symptomatic, and prostate volume parameters as well as serum prostate-specific antigen.

METHODS

The TULIP procedure was performed in 33 patients with benign prostatic hyperplasia with a mean age of 66 years. Patients were evaluated by pressure-flow studies, prostate volume measurement by transrectal ultrasound, and the American Urological Association (AUA) symptom score.

RESULTS

At 3-month follow-up, laser prostatectomy has resulted in an increased maximum flow rate from 6.6 +/- 0.5 to 11.2 +/- 0.6 mL/s and in an objectively proven relief of the urodynamic obstruction, as is evident by a decrease of the average value of the urethral resistance parameter URA and the detrusor pressure at maximum flow rate from 38.3 +/- 2.7 to 21.3 +/- 1.3 cm water and from 62.7 +/- 4 to 38.9 +/- 2.1 cm water, respectively. Symptomatic improvement is evident from a decrease in the AUA symptom score from 20.4 at baseline to 8.8 at 6-month follow-up. Although the total symptom score did not change significantly between 6 months and 1 year follow-up, the score of the symptom "weak stream" was significantly higher again at 12 months follow-up.

CONCLUSIONS

The TULIP procedure is a urodynamically and symptomatically effective treatment. Conclusions about the durability of this treatment modality should be made with reservations.

Modeling of intraluminal heating of biological tissue: implications for treatment of benign prostatic hyperplasia

A computer model for predicting the thermal response of a biological tissue to different intraluminal heating modalities is presented. A practical application of the model is to calculate the temperature distributions during thermal coagulation of prostate by contact heating and radiative heating. The model uses a two-dimensional axisymmetric diffusion approximation method to calculate the light distribution during radiative heating. The traditional Pennes' bio-heat equation is used to calculate the temperatures in the presence of blood flow. An implicit finite difference scheme with nonuniform grid spacings is used to solve the diffusion equation for light distribution and the bio-heat equation. Model results indicate that the radiative heating of prostate by Nd:YAG (1064 mm) and diode (810 mm) lasers can be a more effective and efficient means of coagulating a large volume of prostate, as compared to contact heating of the tissue. Blood perfusion is shown to provide a considerable heat sink as the laser exposure time is increased. Surface cooling by irrigation during the laser irradiation of tissue is shown to be an effective method for delaying tissue explosion and obtaining a large volume of coagulated tissue. The model also shows that the volume of the coagulated tissue is appreciably altered by a change in the rate of energy deposition.

Transurethral Treatment of Benign Prostatic Hyperplasia by Means of Neodym-YAG Laser. Preliminary Report

The Authors are the first in Hungary to report on laser therapy in BPH according to their experience gained in connection with 5 cases. They have verified that operations performed by means of the Nd-YAG laser and specific (SideFire) laser thread may offer a beneficial choice in the initial phase of BPH.

Thermal damage to normal and hyperplastic prostates due to transurethral balloon laser therapy in dogs

Fourteen dogs were studied to determine the level of thermal damage to the normal or benign hyperplastic prostate. Prostates were heated transurethrally by a balloon laser probe (Nd: YAG laser) at various temperatures for 20 min. Coagulative necrosis was observed in the prostate when it was heated above 45.4 degrees C for 20 min. Tissue damage in the bladder neck occurred above 49.4 degrees C, damage to the urethral mucosa occurred above 46.5 degrees C, and damage to the urethral sphincter occurred above 43.2 degrees C. It was calculated that there was a 50% probability of necrosis of the prostate gland occurring when prostatic tissue was treated at 45.0 degrees C for 20 min. Striated muscle cells in the urethral sphincter were more heat-sensitive than smooth muscle cells of the bladder neck or transitional cells of the urethral mucosa. This basic information is essential for the safe application of Nd: YAG laser hyperthermia to the prostate gland.

Transurethral ultrasound-guided laser-induced prostatectomy (TULIP) for benign prostatic hyperplasia: clinical utility at one-year follow-up and imaging analysis

OBJECTIVE

The clinical utility of transurethral ultrasound-guided laser-induced prostatectomy (TULIP) for benign prostatic hyperplasia (BPH) and the laser effect on prostatic tissue were investigated.

METHODS

TULIP was carried out under epidural anesthesia on 30 patients with symptomatic BPH (aged 63-92 years; mean, 73.9 years).

RESULTS

Excluding 4 cases that were lost to follow-up, the mean modified Boyarsky symptom score significantly improved (P < 0.001) from a preoperative level of 22.2 +/- 5.3 to 7.7 +/- 4.3 at three months and 6.2 +/- 4.1 at one year. Maximum flow rate increased from 7.9 +/- 3.4 mL/sec to 14.5 +/- 5.9 mL/sec at three months and 14.7 +/- 6.3 mL/sec at one year (P < 0.001). A decrease in residual urine volume from 72 +/- 65 mL to 10 +/- 18 mL at three months and 16 +/- 17 mL at one year was also noted (P < 0.005). Transrectal ultrasonography revealed that estimated prostate volume was decreased from 39.7 +/- 20.4 mL to 26.9 +/- 20.3 mL at three months (P < 0.05) but it regrew to 32.2 +/- 26.2 mL at one year. Magnetic resonance imaging clearly showed less enhanced area to a depth of approximately 10 mm in the periurethral region, which could be attributable to coagulation necrosis in the prostatic tissue. Adverse effects were limited to epididymitis in 2 cases and no sexual dysfunction was associated with the procedure.

CONCLUSIONS

TULIP is an effective and safe alternative procedure to induce long-lasting relief of prostatic obstruction by coagulation necrosis in the periurethral region.

High intensity focused ultrasound for the treatment of benign prostatic hyperplasia: early United States clinical experience

High intensity focused ultrasound via a transrectal approach was used to treat 15 patients with symptomatic benign prostatic hyperplasia. The first 10 of these 15 patients underwent continuous temperature monitoring of the periprostatic region throughout the treatment. Patients undergoing transperineal thermocouple placement for the purpose of thermometry were treated while under general or spinal anesthesia, whereas 4 of the 5 remaining patients were successfully treated using intravenous sedation alone. Of the 10 patients 9 did not demonstrate a significant temperature elevation. One patient with a small prostatic anteroposterior diameter had a transient elevation of 17C. No patient experienced a complication related to periprostatic heating. Followup was available at 90 days in all patients. At 90 days the symptom scores decreased from a pretreatment value (American Urological Association questions 1 to 7) of 31.2 (range 22 to 38) to 15.8 (range 8 to 31). Peak flow rate increased by a mean of 4.7 ml per second from 9.3 ml per second before treatment to 14.0 ml per second at 90 days. The most frequent complication was that of transient urinary retention in 11 of 15 patients (73.3%) and hematospermia in 7 (46.7%). No adverse reactions persisted at 90 days. This study represents an initial attempt using high intensity focused ultrasound to treat symptomatic benign prostatic hyperplasia. Overall, the safety and effectiveness of high intensity focused ultrasound demonstrated in this pilot study are encouraging.

Thermal changes in the canine prostate after transurethral balloon laser prostatectomy

The histological changes by transurethral balloon laserthermia were examined on 23 canine prostates. Immediately after treatment, three zones were observed; the coagulative zone treated over 60 degrees C for 20 min formed an inner layer, the degenerative zone treated between 60 to 46.1 degrees C surrounded the coagulative zone, and the intact zone treated below 46.1 degrees C formed the outer layer. Coagulative necrosis of the gland, swelling of collagen fibers, and thrombus of the vessels occurred in the coagulative zone, shedding and vacuolation around the nuclei of the epithelial cells and stromal edema were observed in the degenerative zone, while thermal changes were minimal in the intact zone. Both coagulative and degenerative zones developed necrosis and started to slough off within 1 week, forming a cavity in the central portion of the prostate. Reepithelialization of the cavity was complete at 4 weeks and the ducts of the prostate gland opened to the surface of the cavity. This treatment preserved the excretory tract of the prostate gland.

In vivo effects of transurethral balloon laser prostatectomy on the canine prostate

Twenty-three dogs received prostatectomy by transurethral balloon laserthermia, and the in vivo effects and morbidity were evaluated. The prostate was heated transurethrally, and tissue temperature at a depth of 5 mm. from the urethral mucosa was maintained at 60C for 20 minutes. Immediately after the treatment, coagulative necrosis was observed around the urethra to an average depth of 5 mm., and the tissue started to slough off within 1 week. Cavity formation and reepithelialization were complete after 4 weeks. Histologically, no tissue damage was found in the bladder neck or the urethral sphincter. The cavity formation threshold was 46.1C for 20 minutes. There was no incontinence or macroscopic hematuria in any case. No abnormality was found in hematological or biological examinations after treatment. From these data, the clinical use of transurethral balloon laserthermia for prostatectomy is considered both safe and effective.

High-intensity focused ultrasound in the treatment of prostatic tissue

OBJECTIVE

Beginning in 1987, high-intensity focused ultrasound was investigated in the canine model to determine the feasibility of destroying prostate tissue. After demonstrating the ability to ablate prostate tissue reliably in a canine model, a 15-patient pilot clinical study was undertaken at Indiana University in the fall of 1992. This pilot study was undertaken to assess the safety in the human clinical situation, as well as to give some early efficacy results.

METHODS

The early canine feasibility studies were conducted via a suprapubic extracorporeal approach using two separate transducers, one for imaging and the other for therapy. Subsequent to this, a transrectal probe, which had the dual capability of both imaging and therapy, was developed and used to treat canine prostates in a formal, "good laboratory practice" study to determine the safety of this technology prior to beginning treatment of human benign prostatic hypertrophy.

RESULTS

The formal canine studies demonstrated that prostatic tissue could be reliably ablated in the therapy zone. The dosimetry and duty cycle required to ablate canine prostatic tissue effectively was also determined in this study. The study also demonstrated that the prostatic tissue could be ablated without injury to the intervening rectal tissue or periprostatic tissue. The human pilot study has also demonstrated safety of high-intensity focused ultrasound, as well as early efficacy.

CONCLUSIONS

These early clinical results are encouraging, but assessment of efficacy will require a randomized study comparing high-intensity focused ultrasound to sham and to transurethral prostatectomy. This multicenter trial is currently planned.

Second-generation delivery systems for laser prostatic ablation

OBJECTIVE

To assess the effectiveness of a second-generation laser delivery system (Side-Fire) in the treatment of benign prostatic hyperplasia (BPH).

METHODS

Thirty-three patients with documented BPH were treated and evaluated pre- and post-operatively with a follow-up period of twelve to thirty-six weeks.

RESULTS

There was marked improvement demonstrated at three months post lasing in all patient outcome parameters (symptom score, flow rate, and post-void residual volume) using the new Side-Fire right-angled delivery system.

CONCLUSION

Side-Fire catheter laser ablation therapy produces an excellent transition zone ablation in established BPH.

Factors affecting size and configuration of neodymium:YAG (Nd:YAG) laser lesions in the prostate

Laser surgery for benign prostatic hypertrophy is a clinical reality and a promising alternative to traditional transurethral electroresection of the prostatic adenoma (TURP). Current methods of laser prostatectomy involve coagulation of prostate tissue using a quartz side-firing fiber that redirects a Nd:YAG laser beam at 70-90 degrees most commonly by means of a metal reflector. In this communication we describe a method of tissue evaporation using a side-firing fiber that avoids use of a metal reflector by means of internal reflection. It is relatively resistant to damage when coming in contact with tissue. By placing the fiber tip in direct contact with tissue, much larger lesions are created because of more efficient energy transfer resulting in rapid evaporation of tissue under water. In prostate surgery, this phenomenon of accelerated evaporation can be used to bloodlessly evaporate adenomatous tissue creating a defect that resembles that of a traditional TURP.

Characterization of tissue effects produced by the Prolase II lateral-firing neodymium:YAG laser fiber in the canine prostate

The immediate and long term-effects of neodymium:YAG laser treatment with the ProLase II lateral-firing laser fiber in the canine prostate were evaluated. Fourteen male dogs, aged 3 years and older with established benign prostatic hyperplasia, underwent endoscopic ablation of the prostate using the ProLase II fiber. Subjects were treated at laser power settings of 60 watts (6 dogs), 75 watts (4 dogs), or 90 watts (3 dogs), with a mean total energy delivery of 15,000 joules. One dog underwent a sham procedure and served as a normal control. Prostates were examined grossly and histologically at 48 hours, 2 weeks, 4 weeks, or 8 weeks post-treatment. The cross-sectional diameter and volume of tissue ablation were measured in each prostate. Histological studies of the extent of thermal injury to the prostatic tissue and the course of healing of the prostatic urethra were performed. The mean cross-sectional diameter of tissue ablation was 28.6 +/- 4.7 mm and mean volume of tissue ablation was 8.2 +/- 5.1 cc. No statistically significant difference in diameter or volume of tissue ablation was noted between varying power settings. Histological studies showed extensive tissue necrosis with hemorrhage and an acute inflammatory cell infiltrate at 48 hours. By 8 weeks, total resolution of both necrosis and inflammatory changes with complete re-epithelialization of the prostatic urethra was observed.

Prostatectomy by transurethral balloon Laserthermia (PROSTALASE) in the canine

Prostatectomy by transurethral balloon Laserthermia (PROSTALASE) was performed in a canine model. This balloon device monitored by transrectal ultrasound can cylindrically irradiate with a laser beam. The treatment was performed in 8 canines using 15 watts for 20 minutes at 60 degrees C at a 5 mm depth of the prostate from the urethral surface. Immediately following the laser therapy, an area of coagulation necrosis was observed around the urethra to a depth of 4-5 mm from the surface. After 1 week, cavitation formation was seen in 3 or 4 canines by ultrasound, and the urethral reepithelialization was shown in 1 of 2 canines. After 2 weeks, cavitation formation was observed in both canines, and the urethra was completely reepithelialized in one canine. There was no tissue damage in the bladder neck of urethral sphincter and no urinary incontinence in any animal. This system is thought to be simple and, satisfactorily performed, is an effective transurethral prostatectomy.

Interstitial laser prostatectomy

Serial gross and histopathologic examinations of the prostate following interstitial laser prostatectomy in the canine model demonstrated distinct zonal thermal changes around the entire active area of the interstitial thermal therapy (ITT) fiber. A large, well-demarcated area of acute coagulative necrosis immediately surrounded each fiber tract; beyond that were a prominent narrow peripheral zone of marked tissue disruption and an outer zone of hemorrhage. Liquefaction within these coagulative areas was evident within 24 hours, and by 4 days, each lobe of the prostate contained an irregular cavity that became lined by normal-appearing transitional epithelium and that, by 5 weeks, communicated with the prostatic urethra. These postmortem pathologic observations, similar to findings previously reported following transurethral laser prostatectomy, suggest that interstitial laser thermal therapy may provide an additional means for treating benign prostatic hyperplasia in men.