OBJECTIVE:To evaluate lead migration for two different test electrodes and the response to trial stimulation of the S3 nerve root during the selection of patients for a sacral neuromodulation implant to manage lower urinary tract dysfunction. PATIENTS AND METHODS:Twelve women (mean age 49 years, range 23-79; seven with detrusor instability and five with sensory urgency) undergoing peripheral nerve evaluation for refractory lower urinary tract symptoms were recruited. Urodynamics and a urinary diary were completed before and during test stimulation. Two electrodes (the original 041830-002 and new 3057 models, Medtronics Inc, USA) were inserted under local anaesthesia into the S3 nerve roots bilaterally. The location was determined by the functional response to stimulation. Stimulation was applied for one week using the new lead; a positive response was defined as a subjective improvement (> 50%) in urinary symptoms. Lateral sacral X-rays were taken after placement and before removing the lead. The distance from the lead tip to the ventral aspect of the S3 sacral foramen was measured by two assessors. RESULTS:Ten of the women had a positive response; the mean (range) migration of the new lead (on X-ray) was 4 (2-11) mm, and of the old lead was 12 (10-45) mm (P = 0.02). CONCLUSION:The response rate to trial stimulation was greater than in previous studies, possibly reflecting reduced migration of the new lead. The new electrode may reduce the number of test failures caused by lead migration rather than no response.