151 Jaspreet S. Sandhu Department of Surgery, Urology Service, Memorial Sloan Kettering Cancer Center, New York, NY, USA Bipolar transurethral resection of the prostate (BiTURP) is an endoscopic technique used in the surgical management of lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). Monopolar TURP, as described in Chapter 150, is a transurethral endoscopic procedure that relies on electrosurgical resection of prostate adenoma, followed by removal of “prostate chips” from the bladder with an aqueous evacuator. It has been performed since early in the last century, has evolved to be the procedure of choice for surgical treatment of LUTS secondary to BPH, and is often called the “gold standard” surgical treatment for BPH/LUTS. Although monopolar TURP is known to be efficacious in this context, it is associated with reasonably high rates of complications, including hematuria, reoperation, dilutional hyponatremia, and the need for blood transfusion [1]. Advances in optics and energy generation/delivery systems have decreased complications significantly in modern times [2]. However, the number of TURPs performed in the United States continues to decrease yearly, perhaps because of the perception of increased morbidity [3]. The rationale for BiTURP, therefore, is straightforward – to limit the risk of dilutional hyponatremia while leveraging transurethral resection skills that most urologist acquire during training and practice. Most authorities suggest limiting monopolar TURP operating times to 60 minutes because absorption of fluid is proportional to the operative time. Longer operative times lead to increasing risk of dilutional hyponatremia, also known as “TUR syndrome” due to absorption of glycine irrigation [4]. The fact that BiTURP uses normal saline as an irrigant effectively eliminates the risk of dilutional hyponatremia and allows operators to use this technique for as long as needed. This is particularly advantageous in patients with large‐volume prostates or for use in medical education. It should be noted that BiTURP is actually an evolution of transurethral vaporization of the prostate [5], which is a monopolar technique that uses higher current and electrodes with broader contact with tissue to “vaporize” tissue at the cut edge of the resection. BiTURP has been referred to as bipolar vaporesection of the prostate, plasmakinetic vaporization of the prostate, or bipolar resection of the prostate. This nomenclature adds to confusion, particularly with strictly ablative techniques such as photoselective laser vaporization of the prostate or bipolar button vaporization electrode. The “vaporization” referred to in BiTURP is actually the vaporization that occurs of tissue in contact with the cutting loop (active electrode). This is similar to what happens to tissue in contact with the cutting electrode during monopolar TURP. BiTURP relies on the creation of a “plasma corona” at the electrode and this results in roughly 20% of the tissue being vaporized, with the rest resected as prostate chips [6]. BiTURP was first introduced in humans in the early part of this century [7]. The initial reports touted this technique’s ability to use bipolar current through an isotonic irrigant media with results similar to TURP. Most subsequent reports have focused on technologies from different manufacturers and primarily compared results to TURP via either randomized control trials or comparative trials. Surgical therapy is the mainstay for treatment of LUTS secondary to BPH, refractory to medical therapy. Current practice is to offer minimally invasive surgery to patients who do not want or are unfit for a more involved operation. Endoscopic surgery is the gold standard for treatment of LUTS secondary to BPH, with open surgery reserved for those patients with large glands or those who need concomitant procedures [8]. The most recent American Urological Association (AUA) guidelines [8] on the management of BPH/LUTS recommend TURP as the surgical treatment of choice for men with moderate to severe LUTS who are bothered by their symptoms. These guidelines state that the “choice of a monopolar or bipolar approach should be based on the patient’s presentation, anatomy, the surgeon’s experience and discussion of the potential risks and likely benefits” [8]. The European Association of Urology has similar recommendations in its recently release guideline on the management of non‐neurogenic male LUTS, but goes a little further by stating that “B‐TURP offers an attractive alternative to M‐TURP in patients with moderate to severe LUTS secondary to BPO [benign prostatic obstruction], with similar efficacy but lower peri‐operative morbidity” [9]. An updated set of AUA guidelines is currently being formulated and should be available shortly. BiTURP is an endoscopic resection technique that uses a continuous flow resectoscope and a specially designed loop and inner sheath that varies by manufacturer and use. It is a design modification of the monopolar TURP, utilizing a specialized resectoscope and loop that incorporates the active electrode on the loop and return electrode on a separate insulated part of the loop or on the inner sheath of the resectoscope. This allows the procedure to be performed using normal saline as an irrigant, thereby limiting the risk of dilutional hyponatremia (or TUR syndrome), and with potentially less stray current because of the very short distance between the active and return electrodes. The electrode can be used to resect as well as coagulate. Modifications of the electrode also allow vaporization, which will be discussed in a subsequent section. In contrast to monopolar TURP, the irrigant media is usually 0.9% normal saline. Generators are also matched to the loop used and voltage is varied based on impedance to keep the current constant. Bipolar technology platforms currently available are the PK system by Gyrus/ACMI, an Olympus Corporation (Tokyo, Japan) company, the TURis system by Olympus Corporation (Tokyo, Japan), and a bipolar resection system by Karl Storz (Tuttlingen, Germany). Each of these systems uses a continuous flow resectoscope and relies on an active electrode on the cutting element of the loop, with the ability to generate a plasma corona vaporization field in normal saline media. The difference between these platforms is the location of the return electrode. Because BiTURP relies on the ability to generate a current between two poles and the closer the two poles, the lower the voltage needed to generate a current, the return pole (electrode) has to be in close proximity to the active electrode. As such, the return electrode of the PK system is on the loop itself, separated from the cutting element by a few millimeters of insulation. The return electrode for the TURis system is on the inner sheath of the resectosope, and the return electrode for the Storz system is on the loop opposite the cutting element. See Figures 151.1–151.3 for illustrations of the different available loops. Figure 151.1 The Gyrus PK Supersect loop. Figure 151.2 Olympus TURis bipolar loop. Figure 151.3 Karl Storz bipolar loop. The BiTURP, which typically needs a lower voltage differential to generate a high current because of the short distance needed to close the circuit, relies on generators that can change voltage based on tissue impedence and therefore keep current constant. Specially designed generators are matched to each platform. All generators have preset default settings; typical settings for “cutting” are high power (200–280 W for TURis, 160–200 W for PK) and settings for “coagulation” are lower power (120 W for TURis and 80 W for PK). Different loops are also available for the PK system and the TURis system to allow resection of bladder tumors or to perform vaporization without resection. All currently available loop electrodes are single use. Figure 151.4 is an illustration of the Gyrus PK® generator. Figure 151.4 Gyrus PK generator. The surgical technique for BiTURP is similar to that for monopolar TURP, with a few unique aspects. As in other transurethral procedures, preoperative antibiotics should be given. Regional anesthesia (e.g. spinal) or general anesthesia may be used. It is important to note that there should be no dilutional hyponatremia with BiTURP, eliminating the need to monitor mental status and allowing general anesthesia to be used at the anesthesiologist’s discretion. Initial intubation of the urethra should be performed with the help of a visual obturator. If needed, a urethrotomy may be performed to allow entry of larger resectoscopes. Once the bladder is reasonably filled, continuous irrigation should be started, typically with the outflow port open to gravity drainage. Resection is started by first resecting the intravesical component and the median lobe of the prostate. Unlike the monopolar TURP, the cutting electrode loop needs to develop a “plasma corona” prior to the start of resection (see Figure 151.5 for an illustration of a loop with plasma corona active). The loop should be in close proximity to prostate tissue when the operator initiates the cutting current via the foot pedal. At the beginning of the case, this is typically done with the electrode in the bladder and slightly off the prostate surface. Once the corona is formed, resection proceeds in an antegrade fashion for the length of the loop excursion. Prostate chips are formed similar to monopolar TURP and are forced into the bladder by the inflow of normal saline irrigant. Figure 151.5 The plasma corona firing in the bladder. The resection should be performed systematically with prostate landmarks used to limit resection, in particular the verumontanum near the apex. Typically, the intravesical component is first resected, followed by the median lobe from the bladder neck to verumontanum. Care should be taken to avoid injury to the ureteral orifices during this step. Next, one of the two lateral lobes is resected in its entirety prior to proceeding to the other one. Finally, apical tissue and anterior tissue is resected. During resection, the plasma should always be visible. This is especially important as the procedure proceeds, because the cutting loop will add charred tissue to its surface and add impedence to the circuit. As stated above, the corona should be initiated within the bladder or in the lumen of the prostatic urethra without contacting prostate tissue. If the time between stepping on the cutting pedal and the formation of the plasma corona starts to become long, the operator should place the loop in the center of the bladder and allow the plasma to fire for a few seconds. This will clean the loop electrode and allow more efficient vaporization. Once the surgical endpoint is reached, specifically the entire adenoma has been resected from bladder neck to verumontanum and capsular fibers are visible, hemostatis should be achieved. This is done with the coagulation current. During coagulation, no plasma is formed. Instead of point coagulation, as in monopolar TURP, BiTURP relies on coagulating a surface around the bleeding vessel. This is likely due to the shallow penetration of current during BiTURP. Of note, coagulation should be performed intermittently throughout the procedure if significant bleeding is encountered as this will improve visibility during the case. Prostate chips deposited in the bladder throughout the resection are removed near the end of the case with help of an aqueous evacuator. Once all chips have been removed and this has been confirmed by a final survey of the base of the bladder and prostate fossa, a three‐way urethral catheter is inserted and continuous bladder irrigation is begun. Typically, this irrigation is titrated off by the first postoperative day, and the catheter removed. Patients are discharged with a few days of antibiotics. The prostate chips are evaluated by surgical pathologists in a manner similar to prostate chips removed during a monopolar TURP and the same conventions are used to report findings, including T1a or T1b prostate cancer in cases of previously unsuspected prostate cancer. If T1a or T1b prostate cancer is found and the patient is a candidate for prostate cancer treatment, a prostate biopsy should be performed once the patient has healed from the BiTURP – typically six weeks to three months after the procedure.
Ablation of Prostate: Bipolar Resection
Introduction
Patient selection
Surgical equipment
Technology
Surgical technique
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