Monopolar Transurethral Resection of the Prostate1

The surgical management of BPH is evolving at a rapid rate, with several new procedures available that challenge transurethral resection of the prostate as the standard treatment in the surgical management of small to medium sized glands.

For most of the 20th century surgeons were investigating newer, less invasive methods of relieving prostatic obstruction. While the obvious minimally invasive route was transurethral, several technical targets were needed to be met. These included adequate visibility, good, reliable light source and a controllable diathermy generator. With the introduction of the Hopkins rod-lens system, Xenon cold light source and solid state electrosurgical generators midway through the 20th century, modern day TURP came of age. This development was aided by the detailed description of the arterial supply of the prostate by Flocks in 1937.

Transurethral resection of the prostate (TURP) is still considered as the gold standard treatment of obstructive BPH. Although TURP is a safe option in the vast majority, it is not without morbidity. The overall mortality is around 0.2% but in the elderly and high risk patients it is considerably higher.

For effective and safe monopolar TURP, the following are necessary—a very good quality and safe, electrosurgical unit (ESU), compatible irrigant fluid, a good camera and light source and sturdy instrumentation. Needless to say that currently all these are freely available to make TURP really the gold standard operation for obstructive BPH.

Monopolar TURP requires the use of a reliable electrosurgical generator. Electrosurgery utilizes a radiofrequency current to cut and fulgurate tissues. The chosen frequency is important in achieving the desired effects without complications. Current ESU operate at 400,000 to 1 million Hz. Such high frequencies avoid undesirable neuromuscular 2contractions. The characteristics of the electric current will depend on what effect it has in tissues. A continuously alternating radiofrequency current, sine wave, delivers high current and high power. Such a current generates enough heat to cut tissues. Since the heat is so quickly dissipated, the surrounding tissue is not coagulated and hemostasis is poor. In order to fulgurate the tissue, short bursts of high voltage radiofrequency sine waves with a pause between is necessary.

The generator chosen is very important in deciding on the current delivered during the procedure. The power generated is dependent on the current delivered by the unit and the tissue resistance. Modern generators have the ability to adjust the current based on the tissue characteristics to keep the power constant. Older generators did not have this capability. More modern generators use microprocessors to monitor resistance in specific surgical conditions. Dessication occurs by a slow process of driving water out of the cells. Steam, bubbles and change in tissue color to a light brown hue are features of dessication. Changes in tissue characteristics during a TURP affect the performance of the instruments. Tissue charring has an insulating effect and lowers the efficiency of vaporization. Persistent application of power to one area, results in large scale dessication. This results in an increased resistance in the tissue and this necessitates a further increase in power levels. Fulguration is a superficial charring of tissue and requires a coagulation waveform to be generated by the ESU. This waveform is sparked to the tissue surface and heat is widely dispersed by long sparks and intermittent current application. Thus, energy does not penetrate deeply and only a superficial effect is obtained. The cells dry out quickly but do not vaporize, a char effect is obtained and this results in hemostasis.

Historically water was used as the irrigant fluid for TURP. Water is hypotonic and absorption could result in hemolysis, which can be potentially life threatening. Nevertheless, it is the cheapest fluid and has the clearest vision during resection. Majority of urologists now use 1.5% Glycine. While these fluids can be absorbed to produce electrolyte changes, the problem of hemolysis does not arise as these fluids are isotonic with plasma.

Camera systems have really revolutionized resection today. They have high resolution and the magnification that results make identification of tissue landmarks easy. The fiber optic light cables and Xenon light source in addition makes resection effective.

The discovery of the Hopkins rod-lens system provides unparallel clarity of vision. Resectoscope design has improved significantly and become sturdy. The main limiting factor in TURP is the size of the gland. Large glands in excess of 100 gram could take more than 90 minutes, which many consider to be the safe upper limit of resection time. The use of the continuous flow resectoscope has helped speed up resection times. It has also added a safety net to the operation by keeping the intraprostatic pressure low thus reducing the risk of absorption. Another important choice is whether one uses a thin loop or a thick loop for resections. The thin loop allows for more efficient vaporization and cutting. Since the current is not dissipated over a large area, one can achieve more precise tissue ablation. A thick loop by virtue of its larger surface area disperses current over a broad area. This causes current density to be less and produces more effective hemostasis. The choice of loop is the surgeons preference and is dictated by the level of his experience and his comfort levels with technology. 3Many surgeons employ suprapubic drainage using an standard Reuters canula or a suprapubic catheter while resecting large glands. This helps maintain low intraprostatic pressures during the resection and also reduces resection times as the bladder does not fill.

There are three main techniques that urologists use for TURP—the Barnes, the Nesbit and the Flocks. Whichever technique one uses it is important to remember that resection must be systematic and in an organized fashion. Each lobe of the prostate is dealt with individually. Hemostasis is achieved and only then does one resect the other lobe. If the prostate is large and there is a time constraint, there is no harm in doing a planned hemiresection of the prostate or coming back a few days later to complete the rest of the resection.

Resection starts at 11 o'clock by creating a trough at the bladder neck; resection then continues in this trough systematically towards the apex. This effectively detaches the lateral lobe, which is displaced medially and devoid of its blood supply. This detached lobe as well as the middle lobe is then resected together. One of the potential drawbacks of this technique is that in large glands a beginner could lose his way due to the large volume of prostatic tissue in the floor of the fossa.

It is also acceptable that in very large glands a two-stage TURP be done. On one day, one lobe is resected and a few days later during the same hospitalization, the other lobe(s) are resected. There is literature evidence that hemiresection of the prostate as a planned procedure also results in normal voiding.7

Meticulous attention to hemostasis is necessary to prevent catheter blockage post-operatively. A 22 Fr or 24 Fr size 3-way catheter is used by most urologists for bladder drainage. The catheter balloon is inflated as per the surgeons choice. It is important to remember that larger balloon volumes can produce significant bladder spasms. The choice of instituting postoperative irrigation is surgeons’ preference and is usually carried out for a minimum of 24 hours after surgery.

Transurethral prostatectomy is an operation that distinguishes the “men from the boys”. It is an operation that is both difficult to teach and also learn. However, the advances in camera systems have overcome both these drawbacks. The advent of other minimally invasive treatments for the prostate especially laser prostatectomy has challenged the gold standard procedure. Only time will decide if it will continue to remain so.