Bipolar, monopolar transurethral resection of the prostate yield comparable outcomes

October 1, 2010

In the treatment of benign prostatic obstruction, bipolar and monopolar transurethral resection of the prostate yield comparable outcomes at 12 months.

Bristol, United Kingdom-In the treatment of benign prostatic obstruction, bipolar and monopolar transurethral resection of the prostate yield comparable outcomes at 12 months. However, monopolar resection is associated with a small but distinct elevated risk of transurethral resection syndrome and because of this, it might be wise to avoid applying the monopolar procedure in selected patients, say the authors of a study from the Bristol Urological Institute, Bristol, UK, and other UK institutions.

"You should probably go with bipolar in the elderly, in patients with significant comorbidities, and in patients with history of cardiac or blood pressure problems," said Samih Al-Hayek, MD, of the Bristol Urological Institute. "If a person is fit with normal sodium level and has had no previous cardiac problem, you can go with monopolar or bipolar."

Dr. Al-Hayek based his comments on a study of 210 patients randomized to undergo bipolar TURP using normal saline irrigations (110 patients) or monopolar TURP using the standard glycine solution (100 patients). He presented the study at the AUA annual meeting in San Francisco on behalf of Anthony Timoney, MCh, of Bristol Urological Institute, and co-authors, who could not attend.

Some 76 patients in the monopolar group and 80 in the bipolar group were followed at 3, 6, and 12 months with International Prostate Symptom Score and flow rates. Postoperative assessments of efficacy showed no significant difference, with both groups demonstrating comparable improvements in IPSS, quality of life evaluations, Qmax, and residual volumes at 12-month follow-up.

However, there were differences. Fluid absorption in the monopolar arm was higher at 1,015 mL compared to 496 mL in the bipolar group (p<.001). Serum osmolity was lower in the monopolar arm: 284 mOsm/L compared to 289 mOsm/L (p<.001) in the biopolar arm.

One patient in the monopolar arm had sodium <125 mmol/L. Three patients (3%) in the monopolar arm developed TUR syndrome, and nine presented with at least two symptoms of the syndrome but with nondiagnostic declines in serum sodium. Current literature puts the incidence of the syndrome in TURP patients at 2% to 3%.

Dr. Al-Hayek said the nature of the irrigation fluids lay at the foundation of the syndrome. Glycine is the irrigation fluid used in the monopolar procedure, whereas normal saline is employed in the bipolar procedure. Since saline has its own salts, absorption is more pronounced when glycine is the irrigant.

"In patients with substantial comorbidity, surgeons are recommended to employ the bipolar procedure because glycine can be toxic to the heart," Dr. Al-Hayek said. He noted work by colleagues showing that glycine induced some changes in electrocardiograms.