Sacral neuromodulation for nonobstructive urinary retention--is success predictable?

PURPOSE: We investigated whether there are factors which can predict successful stage II (permanent) sacral nerve stimulator (InterStim) implantation for patients with nonobstructive urinary retention.
MATERIALS AND METHODS: We retrospectively reviewed our sacral neuromodulation database from January 1, 1999 to January 1, 2006. A total of 29 patients were referred to the William Beaumont Hospital Department of Urology for nonobstructive urinary retention. All patients completed a 3-day voiding log followed by test stimulation. Patients underwent test stimulation for a 2-week trial period. Those who experienced 50% improvement in void volume and/or catheterization frequency subsequently underwent permanent implantation. We reviewed patient charts with respect to age, sex, duration of retention, underlying diagnosis for retention and voiding ability.
RESULTS: Of the 29 patients 15 were men and 14 were women. Mean patient age was 58.8+/-16 years (range 18 to 82). The mean age of the men in the study was 55.5+/-18 years while the mean age of the women was 62.3+/-14 years. Although all the patients performed intermittent self-catheterization 18 were able to void (more than 50 cc per void). The remaining 11 patients had minimal (50 cc or less) or no ability to void. Of the 18 patients who were able to void 12 (67%) underwent successful permanent implantation. However, voiding improved after test stimulation in only 2 of the 11 patients (18%) who had been unable to void. This difference was statistically significant (p=0.02) and suggests that pre-implantation ability to void can predict success of test stimulation.
CONCLUSIONS: Patient ability to void predicts success of first stage test stimulation. Although we would still offer a trial of sacral neuromodulation to those with nonobstructive urinary retention and the inability to void, this study would allow better counseling regarding the likelihood of successful outcome.