Transurethral Thermal Ablation of Prostate

by

Dr Chin Chong Min

Urologist

Division of Urology

Dept of Surgery

Toa Payoh Hospital, Singapore 1129.

WHAT IS IT?

Thermal treatment for symptomatic benign prostatic hyperplasia has been available for several years now. The initial temperatures of up to 48 degrees Celsius have since been found to be ineffective, producing only improvement in the irritative symptoms but not the obstructive parameters. Newer delivery systems can now produce higher energies, achieving temperatures of more than 70 degrees Celsius. At this setting, human tissues reliably undergo coagulative necrosis - a process termed thermoablation.

HOW DOES IT WORK?

Thermal tissue ablation works through destruction of the neuromuscular receptors at the bladder neck & prostatic urethra, leading to improvement in the irritative symptoms. More importantly, prostate tissue necrosis occurs & this leads to improvement in obstructive symptoms. The resultant effect is that flow rate increases & residual urine & symptom score decreases.

WHO IS SUITABLE?

Patients with symptomatic BPH with prostatic volumes of more than 20 ml but less than 80 ml & whose peak flow rate is less than 10 ml/sec. Pretreatment assessment includes:

* Clinical history & Physical (includes digital rectal) examination,

* International Prostate Symptom Score (IPSS),

* Blood chemistry,

* Serum PSA,

* Uroflowmetry,

* Transrectal Ultrasound of the Prostate (TRUS), In those with a raised PSA level, a

transrectal ultrasound guided biopsy is required to confirm BPH & exclude cancer.

TRUS also confirms the size of the gland & the length of the prostatic urethra.

Exclusion Criteria are:

* Cardiac pacemakers,

* Metallic prosthesis in hip/knee joint,

* Neurological bladder dysfunction,

* Bladder neoplasm,

* Bleeding diasthesis,

* Impaired mental state.

WHAT IS AVAILABLE?

Presently, there are 2 modalities for performing thermal ablation of the prostate:

* TransUrethral RadioFrequency (TURF)

* TransUrethral Needle Ablation (TUNA)

TURF:

It is achieved using the

THERMEX-II (Direx Medical Systems)

. It is easy to perform, requiring a one hour outpatient treatment session without need for general or regional anaesthesia.. A transurethral foley-like catheter containing the delivery system electrode is inserted under local anaesthesia. The system delivers radiofrequency waves that result in temperatures reaching 80 degrees Celsius. Safety features incorporated are continuous temperature monitoring in the prostate, external sphincter & rectal wall, with an override program should these temperatures exceed safety limits. The patient experiences an initial burning sensation that settles by 15 mins & there may be slight & transient haematuria. A supra-pubic catheter is inserted at the end to circumvent acute urinary retention that may occur. This catheter is removed by the first or second week after treatment.

TUNA:

TUNA uses 2 needles loaded onto a rigid transurethral device that is inserted under local or regional anaesthesia. It also uses radiofrequency energy to cause interstitial thermoablation as the needles are systematically projected into the enlarged prostate lobes. The prostatic urethral lining is preserved as there are retractable shields that can cover the needles. Temperatures reached exceed 80 degrees Celsius & treatment time is about 30 mins. Again, a supra-pubic catheter is placed as the initial oedema can cause urinary obstruction.

HOW EFFECTIVE IS THE TREATMENT?

Initial results show that thermal treatment is safe & well tolerated that has the distinct advantage of relieving prostatic obstruction in high risk patients or those afraid of undergoing TURP and its associated morbidity. It can be done as day surgery, thus reducing hospitalisation costs. There is significant decrease in symptom score. The increase in mean peak flow rate & reduction in the mean prostatic volume is reported to be up to 40%.