Transperineal Laser Ablation of Prostate (TPLA™)

Abstract

This chapter provides a comprehensive overview of Transperineal Laser Ablation of the prostate (TPLA™) as a therapeutic option for Benign Prostatic Hyperplasia (BPH). BPH is a prevalent condition among aging men, characterized by non-cancerous enlargement of the prostate gland, leading to lower urinary tract symptoms (LUTS) and impacting quality of life. TPLA™ emerges as a minimally invasive technique leveraging the precision of laser energy to induce coagulative necrosis in targeted prostatic tissue, thereby reducing prostate volume and alleviating symptoms. The chapter systematically reviews the procedural aspects of TPLA™, including patient selection criteria, preoperative preparation, and step-by-step surgical technique. Clinical outcomes are discussed, with a focus on symptom relief, improvement in urinary flow rates, and reduction in prostate volume. Furthermore, the safety profile of TPLA™ is examined, documenting the incidence and management of potential complications. In conclusion, TPLA™ represents a promising addition to the therapeutic armamentarium for BPH, offering a balance of efficacy and safety, ensuring high rates of preservation of sexual function.

1. Introduction

Despite the technological progress achieved in standard surgical techniques for benign prostatic obstruction (BPO), they are still not devoid of side effects and require general or spinal anesthesia as well as hospitalization. Recently, several ultra-minimally invasive surgical techniques were developed with the main goal of finding a compromise between efficacy on urinary symptoms and ejaculation [1]. However, an expanded role of these novel ultra-minimally invasive techniques could be in the setting of highly comorbid patients, potentially not eligible for more invasive surgical procedures [2]. In this view, transperineal laser ablation (TPLA™) of prostate adenoma has shown promising results on efficacy, safety, and impact on sexual function, being feasible in an outpatient setting and using local anesthesia [3]. While the procedure boasts numerous advantages, from the available scientific evidence, a lack of standardization emerges concerning patient selection, treatment execution modalities, intraoperative features, postoperative management, and follow-up [4].

2. Diode laser

The word laser is acronymous for “light amplification by stimulated emission of radiation.” Laser light is generated by an energized material (e.g., gas and crystal), and after being absorbed by a tissue, it is converted into thermal energy.

The laser energy has specific features that ensure predictable and precise results. The laser radiation is collimated, coherent, and monochromatic. The term collimated means that the beam travels in only one direction, allowing the laser light to easily enter in very thin flexible optic fibers. The laser energy is defined as coherent because all the photons are emitted at the same time with the same phase, allowing it to reach high energy levels in a short time. Lastly, the laser beam is composed of a single wavelength; it provides specific and selective interaction with tissue chromophores, for this reason it is called monochromatic.

TPLA™ is a modern surgical technique that exploits the benefits of a diode laser to obtain the ablation of prostate adenoma.

2.1 Technical features

In case of diode lasers, the radiation is obtained by a semiconductor-based generator. Depending on wavelengths, commercial lasers emit light in a frequency range of 375–1800 nm. TPLA™ adopts a diode laser with a wavelength of 1064 nm. This wavelength ensures an optimal laser ablation and lower absorption coefficient, which allows the best light penetration into tissues. The specific and selective interaction with the tissue results in a micro-invasive and organ-sparing treatment.

2.2 Biological effect

When the diode laser energy is absorbed by the prostatic tissue, the local temperature increases.

This heating starts to damage the cells until a coagulative necrosis is induced. This phenomenon begins after reaching 60°C inside the tissue, the temperature at which denaturation of proteins begins. As a result, the alteration caused by the laser determines the genesis of a necrotic area that, after an initial inflammatory response, is naturally reorganized by the body hesitating in a scar zone. The maximum extension of the necrosis area is found 72 hours after treatment. Cell damage due to hyperthermia and the occlusion of small and medium-sized blood vessels persist during the days after. For these reasons, the effects of treatment are not immediate, as it takes a few days before starting the cytoreduction process. During the 4–8 weeks after treatment, the scarring processes will be completed with a consequent volume reduction of prostatic gland and urethra decompression.

3. Echolaser system

To date, the only system available to perform transperineal laser ablation of the prostate is the EchoLaser™ (Elesta SpA, Calenzano, Italy). The system consists in two different units – a multisource diode laser generator and the Echolaser Smart Interface – that need to be connected with an ultrasound biplanar probe to plan and execute the ablation.

3.1 Laser generator

The multisource laser generator is composed of four different and independent channels for fiber connection. Each of the four channels is entirely independent of the others; hence, they can be set to different power levels, and it is possible to suspend the laser energy delivery from one or more channels without interrupting the others. Each channel can be connected to a 300-micron optical fiber, enabling the delivery of a variable amount of energy up to a maximum of 6000 J per fiber. The delivery power can be modulated up to a maximum of 7 W (Figure 1).

Figure 1.

The Echolaser system with laser generator and the ESI system monitor.

3.2 Echolaser smart interface

The second module of the Echolaser system consists of the Echolaser Smart Interface (ESI), an interface that allows for treatment planning based on the morphological characteristics of the prostate and guides the positioning of the laser fibers. Echolaser Smart Interface (ESI) technology allows the visualization of needles trajectories during their insertion. ESI overlaps on the US image a cyan area where critical structures should not be contained. This area is designed by changing different parameters to best fit the volume and shape of the prostate adenoma (Figure 2).

Figure 2.

The Echolaser smart interface (ESI).

This dedicated simulation software helps the user to plan the treatment, facilitating the assessment of the following parameters:

• Insertion angle

• Number and position of needles

• Mutual needle position

• Different energy levels (to be set by the user)

• Number of pull-backs (if needed, see the dedicated paragraph 6.4)

• Distance of pull-back

4. Patient selection

TPLA™ is an ultra-minimally invasive option for the treatment of lower urinary tract symptoms (LUTS) due to benign prostatic obstruction (BPO). Despite the increasing utilization of this technique, as of today, it has not been included in the recommendations of international guidelines, and there is no standardization in patient selection.

In terms of dimensions, an essential prerequisite for adequate ablation is a prostatic volume > 30 ml; nevertheless, there is no upper dimensional limit from a technical standpoint. Some authors discourage the procedure in case of a large median lobe (>1.5 cm); however, opinions in the literature are divergent [3]. TPLA™ should be avoided in cases of urethral stenosis, bladder neck contracture, prior prostate surgery, and severe reduction in bladder contractility. The presence of an indwelling catheter is not a contraindication to treatment. The presence of anal stenosis might pose difficulty in performing the treatment due to the requirement of positioning a transrectal ultrasound probe.

The procedure represents a valid option for patients with moderate to severe urinary symptoms, who are motivated to preserve ejaculation, unable to tolerate medical therapy, or deemed unfit for traditional surgery due to high anesthesiologic or perioperative risk.

5. Preoperative preparation

The TPLA™ is a simple and quick procedure; however, a meticulous preparation of equipment and operating settings is suggested to facilitate its execution.

5.1 Preliminary assessment

For a comprehensive preparatory assessment of the patient, it is advisable to collect routine blood testing and functional questionnaires (The International Prostate Symptom Score, IPSS; the International Index of Erectile Function, IIEF-5; Male Sexual Health Questionnaire-Ejaculatory Dysfunction Short Form, MSHQ-EjD SF) and non-invasive urodynamics data (maximum flow rate, Qmax; post-void residual, PVR) [4].

In patients taking antiplatelet or anticoagulant medications, discontinuation of these drugs should be evaluated on a case-by-case basis; however, it is not mandatory for the execution of the treatment.

5.2 Medical equipment and operative setting

The procedure can be performed in an outpatient setting equipped with an examination table featuring dedicated leg supports. The availability of a biplanar ultrasound probe is a necessary condition for performing the treatment. A sterile field with all necessary equipment for the procedure will be set up on a serving trolley:

• 3-way 18Ch catheter

• Antiseptic for skin disinfection (e.g., povidone iodine)

• Lidocaine

• Syringe and needles for subcutaneous anesthesia and periprostatic block

• Introducer needles (21G Chiba needles)

• Optical fibers: 300 μm quartz

• Sterile drapes

5.3 Patient positioning

The patient is placed in the lithotomy position on leg supports. A three-way 18-F Foley catheter is placed with continuous irrigation to ensure cooling of the urethral wall during lasing time, avoiding possible thermal damage. Subsequently, the perineum is exposed using adhesive tapes, and the sterile surgical field is prepared.

5.4 Antibiotic and antithrombotic prophylaxis

To reduce perioperative infectious risk, it is advisable to prescribe antibiotic prophylaxis. Perioperative intravenous single shot of 2 g cephazolin is administrated within 1 hour before the procedure. Medical thromboprophylaxis is usually not required.

5.5 Anesthesia

One of the primary advantages of this technique is the feasibility to be performed under local anesthesia, optionally combined with conscious sedation. The method of performing local anesthesia is similar to that used for transperineal prostate biopsies: initial anesthesia of the perineal skin is followed by a periprostatic block. The recommended dosage of anesthetic is approximately 30 ml of 1% lidocaine. According to patients’ preference, it’s possible to administer oral benzodiazepines or intravenous midazolam for conscious sedation.

The decision to perform the procedure under local anesthesia ensures greater speed of execution, the ability to treat patients with high anesthetic risk, and the use of an outpatient setting, resulting in economic and organizational advantages. However, based on operating room availability and/or patient and operator preferences, the procedure may also be performed under spinal or general anesthesia.

6. Surgical technique: transperineal laser ablation of prostate adenoma

Two distinct phases of the surgical procedure can be identified: fiber placement and laser ablation. The successful outcome of the treatment relies on meticulous preoperative planning.

6.1 Transrectal ultrasound and surgical planning

After setting up the surgical field with appropriate sterile draping, the biplanar ultrasound probe for transrectal ultrasound is introduced. At this point, the periprostatic block is performed by injecting approximately 15–20 ml of 1% lidocaine posteriorly, laterally, and anteriorly to the prostatic capsule. Subsequently, measurements of prostate and prostatic adenoma dimensions are taken. Depending on the morphology and size of the gland, the treatment will be planned with the ESI system. Using ESI, the intended treatment area will be visualized, with larger volumes as the delivered energy increases, up to a maximum of 1800 J per fiber. In the case of large prostates, if it is necessary to expand the treatment area, it is possible to plan an ablation with two fibers per lobe and/or plan a pull-back for the treatment of the apical portion of the adenoma. For each fiber, it is possible to set different ablation areas, different pull-back lengths, and visualize the intended treatment areas both in sagittal and axial view (Figure 3).

Figure 3.

Surgical planning with ESI system. The cyan area represents the virtual extension of the ablation.

6.2 Needles and fibers positioning

In light of the planned ablation, the introducer needles are positioned, readily available in the kit provided by the manufacturer. These consist of a 21G Chiba needle, which also features a stopper to secure it in place once the desired position is reached. The needles can be inserted either with a dedicated needle guide or freehand, depending on the operator’s preference and experience in transperineal approach. After inserting the introducer needle, it is crucial to verify that safety distances are respected in the axial plane. The needle tip, visualized ultrasonographically as a hyperechoic point, should be at least 8 mm away from the urethra and the prostatic capsule bilaterally. At this stage, the ESI system simulation comes to aid once again, displaying a cyan circular area with the needle at its center, showing the hypothetical treatment area with the safety distances already respected. When two needles are placed per lobe, the minimum distance to maintain between each needle is 5 mm.

Next, the stylets of the Chiba needles are removed, and the optical fibers are inserted. These fibers extend 10 mm beyond the needle tip, which is why safety distances in the sagittal plane with the bladder neck need to be checked only after their insertion; the bladder neck should be at least 15 mm away from the fiber tip. Once again, the ESI system can be utilized at this stage. Once the final position of the needle-fiber system is established, it can be secured using the stopper (Figures 4–6).

Figure 4.

Treatment with two needles per lobe. Fibers position in the perineum skin.

Figure 5.

Treatment with two needles per lobe. Fibers position in the prostate at transrectal ultrasound.

Figure 6.

Longitudinal view after fiber insertion. The fiber tip goes 10 mm ahead of the needle tip. The distance from bladder neck must be checked after fiber insertion.

6.3 Ablation settings

The laser fiber consists of an energy delivery tip and a connector that must be connected to the generator. Before proceeding with the insertion of the laser fiber into the needle, it is advisable to verify its proper functioning. Upon activation, it emits a flashing red circle.

There is no standardization regarding the energy delivery mode. The generator allows for energy delivery with variable power ranging from 0 to 7 W. Typically, it is advisable to start the ablation with a power of 5 W and potentially reduce it to 3 W in case of discomfort or intense burning sensation reported by the patient. In case the procedure is performed in the operating room under spinal or general anesthesia, it is possible to execute the entire procedure with a maximum power delivery of 7 W.

The ablation is initiated by the operator using a dedicated pedal, which allows for interruption of the procedure at any time. As soon as the energy delivery begins, it is advisable to gently move the fibers to facilitate ignition. The ablative effect will manifest ultrasonographically as the formation of hyperechoic bubbles (bubbling effect) (Figures 7 and 8).

Figure 7.

Hyperechoic bubbling effect during laser ablation, longitudinal view.

Figure 8.

Hyperechoic bubbling effect during laser ablation, axial view.

6.4 Pull-back technique

As described in the preceding paragraphs, the maximum area that can be treated corresponds to a delivery of 1800 J. The effect of the delivered energy indeed reaches a plateau volume at this threshold: giving more than 1800 J in a single illumination will not increase the treated volume. Therefore, to achieve a larger treated area, two alternatives are possible: increase the number of positioned fibers and/or perform a new ablation by retracting the fiber itself into the most apical portion of the adenoma. This latter method is called the pull-back technique. It involves a second ablation performed after retracting the fiber by 5–10 mm. Its execution can be planned in advance with the ESI system, which is crucial for those who are new to the technique. Often, the hyperechoic effect generated by the treatment makes it difficult to identify the fiber within the prostatic parenchyma after the first ablation. For this reason, it is possible to determine the retraction distance using the graduated notches positioned on the needle and spaced 10 mm apart.

After the fiber retraction, a second ablation is performed. Once again, it is possible to deliver energy ranging from 1200 to 1800 J depending on the volume to be treated. The overall duration of the treatment varies according to the delivered energy, power, and number of pull-backs; for a prostate of average size (approximately 60 ml), it ranges from 5 to 10 minutes.

6.5 Technical nuances

The transperineal laser ablation of prostate adenoma stands at the forefront of minimally invasive interventions for managing benign prostatic hyperplasia. As an innovative technique, mastering the nuances and optimizing procedural efficacy are paramount for medical professionals engaged in its practice. Below are some technical suggestions and tips to enhance the operator’s technical skills and improve the outcome of the procedure.

• High-volume prostates: In case of prostatic volume > 60–70 ml consider positioning four fibers (two fibers for lobe) and performing a second ablation using the pull-back technique;

• Asymmetric lobes: In case of asymmetric lobes, consider positioning three fibers and/or delivering different amounts of energy to the two lobes;

• Prostatic calcifications and cysts: In case of prostatic calcification and cysts, place the fiber tip a few millimeters away from it to allow the propagation of the laser energy;

• Needle guidance: Using needle guidance may be very useful during the first procedures or in case of low experience with the transperineal approach. The freehand needle positioning ensures more dexterity and flexibility, allowing the place of the fiber into the exact desired point and potentially adjusting the insertion angle to reach certain parts of the adenoma (e.g., in cases of prostates with greater anteroposterior development, the anterior part of the adenoma may be difficult to reach due to the presence of the pubis);

• Evaluation of hyperechogenicity effect: during the ablation, the treatment effect is ultrasonographically translated into a hyperechoic signal. However, its extent does not accurately reflect the actual ablation size. For these reasons, it is crucial for the operator not to be influenced by this ultrasound artifact but to always rely on the preparatory planning carried out beforehand with the ESI system.

7. Postoperative management

After the treatment, the clinical effect is not immediate. The process from coagulative necrosis to complete absorption of the ablated tissue requires a period ranging from 4 to 8 weeks. Consequently, the clinical benefits are not direct but follow the course of the cytoreductive process.

In the postoperative period, ensuring good clinical outcomes relies heavily on proper therapeutic management and tailoring choices to the patient’s characteristics and the treatment performed.

7.1 Catheter removal

The timing of urinary catheter removal in patients undergoing TPLA™ is one of the most debated topics in the literature. Some authors advocate for immediate removal of the urinary catheter at the end of the treatment, while it is common practice to wait 5–7 days before proceeding with catheter removal [3, 4].

This allows for an initial reduction of edema that develops following the treatment, which could have a ‘paradoxical effect,’ resulting in an increased risk of urinary retention. In particular clinical conditions, such as in the case of catheters carriers, history of urinary retention or in case of a high amount of delivery energy the catheter may be left in place for a longer period (up to 2 weeks). On the other hand, in young patients, not strongly obstructed, with medium to small-sized prostates, it may be possible to attempt catheter removal at the end of the treatment and await subsequent resumption of spontaneous micturition.

7.2 Medical therapy

After catheter removal, the patient may also experience urinary symptoms consistent with the inflammatory process underway. Particularly common symptoms include frequent urination, urgency, and dysuria. In this phase, it is important to manage inflammatory symptoms with appropriate pharmacological support. This ensures symptom relief and simultaneous reduction of the infectious risk associated with the procedure.

A common choice is to administer antibiotics and anti-inflammatory drugs for at least 7–10 days, and in some cases to continue BPH therapy for 1 month. In detail, a possible therapeutic regimen is as follows:

• Low dose Corticosteroids: Methylprednisolone for 10 days (in case of severe diabetes: Ibuprofen 600 mg bid for 7 days);

• Antibiotics: Cefixime 400 mg daily for 5 days;

• Alpha blockers: e.g. Alfuzosin for 20 days;

• NSAIDs: e.g. Ibuprofen 600 mg on demand in case of pain.

8. Complications

Transperineal laser ablation (TPLA™) has emerged as a minimally invasive treatment option for benign prostatic hyperplasia (BPH), offering promising outcomes with reduced morbidity compared to traditional surgical approaches. However, like any medical intervention, TPLA™ is associated with potential complications that necessitate thorough understanding and management. In the literature, the overall complication rate ranged from 0 to 13%, and there were mostly early complications within 30 days of treatment [3].

Below are listed the possible complications:

• Urinary retention: Either acute or delayed, it can occur following TPLA™ due to post-procedural edema or prostatic swelling. Patients should be monitored closely after catheter removal, and urinary catheterization may be required to relieve obstruction;

• Hematuria: It can occur more frequently in patients taking antiplatelets or anticoagulants. It is usually mild, and it typically resolves spontaneously within a few days. However, in case of severe or persistent hematuria may necessitate intervention, including bladder irrigation or clot evacuation;

• Urinary tract infections (UTIs): UTIs are potential complications of TPLA™. Prophylactic antibiotics are administered perioperatively to reduce the risk of UTIs and are typically continued for 5–7 days after the procedure;

• Prostatic abscess: It is a very rare complication, with an incidence ranging from 0 to 5% of cases in the literature. The formation of a prostatic abscess occurs due to bacterial proliferation in the tissue cavitation generated by laser ablation. It is treated with antibiotic therapy and percutaneous ultrasound-guided drainage;

• Ejaculatory dysfunction: TPLA™ may result in ejaculatory dysfunction, characterized by reduced ejaculate volume or retrograde ejaculation. Preservation of ejaculatory function depends on the extent of tissue ablation and proximity to the ejaculatory ducts. Its rate of incidence ranges from 0 to 4%;

• Erectile dysfunction, urethral stricture, and incontinence: These are extremely rare adverse effects if the treatment is performed while adhering to the safety distances described in the preceding paragraphs.

9. Results

Studies evaluating the efficacy of TPLA™ consistently report significant improvements in LUTS scores following the procedure [5]. Reductions in International Prostate Symptom Score (IPSS) and improvement in quality of life (QoL) metrics are commonly observed within weeks to months post-TPLA™. Long-term follow-up studies demonstrate sustained symptom relief, with many patients experiencing durable benefits over several years [6, 7]. This is also reflected in the urodynamic parameters: TPLA™ effectively improves urodynamic parameters associated with BPH, including increased urinary flow rates and reduced post-void residual volume. These improvements correlate with symptomatic relief and contribute to enhanced urinary function and patient satisfaction. From a safety standpoint as well, it has been demonstrated that the procedure is safe with a very low risk of adverse events. Additionally, TPLA™ can be performed under local anesthesia, reducing the risks associated with general anesthesia and facilitating outpatient procedures. In this regard, a recent study evaluated the outcomes of this technique in a population of multi-morbid and high-risk patients, confirming its safety and efficacy even in this subset of patients [2]. If compared to the current gold standard therapy represented by transurethral resection of the prostate (TURP), the risk of sexual and ejaculatory dysfunctions is significantly lower, with a lower increase of the Qmax values but a similar impact on urinary symptoms evaluated by the IPSS questionnaire, as demonstrated by two RCTs [8, 9].

10. Conclusion

In conclusion, TPLA™ emerges as a promising minimally invasive technique for the treatment of Benign Prostatic Obstruction. Through the application of laser energy, TPLA™ offers a targeted and tailored approach to address the enlarged prostate tissue, providing relief from bothersome lower urinary tract symptoms while preserving sexual function and minimizing complications.

TPLA™’s efficacy in reducing prostate volume and improving urinary flow parameters has been demonstrated in numerous clinical studies. Furthermore, the transperineal approach offers advantages over transurethral procedures by reducing the risk of complications such as urethral strictures, urinary incontinence, and sexual dysfunction. This approach also allows for precise targeting of prostate tissue, minimizing damage to surrounding structures and promoting quicker recovery times.

The aforementioned characteristics make the technique appealing to younger patients, who are strongly interested in preserving ejaculatory function. However, it is also safely applicable to elderly, frail patients with multiple comorbidities, who would otherwise be excluded from any other surgical therapeutic option.

The technique also presents advantages from an economic and management perspective: the possibility of performing it in an outpatient setting and under local anesthesia drastically reduces the costs related to hospitalization and operating room utilization. From a public health perspective, it may help to reduce waiting times for surgery.

Conflict of interest

The authors declare no conflict of interest.