Current issues of ACP Journal Club are published in Annals of Internal Medicine


Transurethral microwave thermotherapy for bladder obstruction

ACP J Club. 1993 July-Aug;119:15. doi:10.7326/ACPJC-1993-119-1-015

Source Citation

Ogden CW, Reddy P, Johnson H, Ramsay JW, Carter SS. Sham versus transurethral microwave thermotherapy in patients with symptoms of benign prostatic bladder outflow obstruction. Lancet. Jan



To compare transurethral microwave thermotherapy and a sham treatment for symptom improvement and placebo effect in men with prostatic bladder outflow obstruction.


Randomized, single-blind, controlled trial.


A prostate clinic in a British hospital.


43 men (mean age 67 y) with moderate-to-severe symptomatic benign prostatic outflow obstruction (Madsen score > 8 for ≥ 6 months; prostate length, 35 mm to 50 mm; and peak flow rates ≤ 15 mL/s with minimum voided volume of 150 mL). Exclusion criteria included renal dysfunction, previous therapy, urinary retention requiring catheterization, prostate cancer, other diseases, or conditions making treatment impractical. Follow-up was 93%.


The treatment unit (Prostatron, Technomed International) contained a microwave generator, urethral applicator-cooler, and fiberoptic temperature monitor. After the applicator was in place, patients were randomized to treatment (n = 21) or sham (n = 22).

Main outcome measures

Peak flow rate, voided volume, residual urine, Madsen symptom scores, quality of life, night and day frequency, and complications. Patients were examined and filled out questionnaires before treatment and 3 months later. Madsen symptom score assessment was changed from unblinded to blinded midway through the study.

Main results

5 patients in the treatment group (1 requiring treatment) and none in the sham group had initial urine retention {95% CI for the 23% difference 5% to 40%}*. The groups did not differ for other complications, quality of life, frequency, or voided volume. The Madsen score decreased by 70% in the treatment group and did not change in the sham group (P < 0.01). The treatment group compared with the control group had a greater increase in peak flow rate (53% vs. 7% increase {P < 0.025}*) and a greater change in mean residual urine volume (92% decrease vs. 45% increase {P < 0.005}*).(* Numbers calculated from data in article.)


Transurethral microwave thermotherapy decreased Madsen symptom scores and residual urine volumes and increased peak flow rates for men with benign prostatic bladder outflow obstruction. Men who received a sham treatment had smaller changes in most symptoms and an increase in residual urine volume.

Source of funding: Not stated.

For article reprint: Dr. C.W. Ogden, Prostate Unit, Department of Urology, Charing Cross Hospital, London W6 8RF, United Kingdom. FAX 44-81-846-1757.


This study reports both subjective and objective improvements in men treated with transurethral microwave thermotherapy. Ogden and colleagues are to be complimented for designing the first controlled study of this procedure. It is well established that placebo effects can account for a substantial amount of the improvement observed in clinical studies of men with benign prostatic hyperplasia. Unlike drug trials where placebo pills can be given, appropriate controls for surgical procedures and medical devices are not so simple. In this study, although the patients were blinded to treatment, the investigators were not. The fact that the investigators changed the procedure for administration of the Madsen Symptom Score halfway through the study because of an absence of placebo effect implies that a review of the efficacy data occurred while the study was ongoing. This can lead to unintentional bias and limits the value of the subjective data collected. No differences were found for quality of life or daytime or night-time frequency. Changes in Madsen symptom score were observed but should be interpreted with caution, given the potential bias from lack of blinding early in the study.

The strongest data come from the objective results showing a 53% increase in peak-flow rate and a 92% decrease in residual volume at 3 months. Proper interpretation of these data, however, would require between-group and within-group statistics to be included in the tables. The 45% increase in residual volume over 3 months in the sham group suggests that the procedure of catheter insertion may itself have a deleterious effect. This is supported by the frequent complication of hematuria in both treatment groups.

In conclusion, the improvement in urinary flow after 3 months suggests objective benefit from the procedure, but complications were frequent. Follow-up beyond 3 months and more vigorous evaluation of symptom changes are necessary to determine the maintenance of this effect and the true value of the procedure as an option for treating men who have benign prostatic hyperplasia.

Glenn J. Gormley, MD, PhD
Merck Research Laboratories Rahway, New Jersey, USA