The value of urodynamic tools to guide patient selection in sacral neuromodulation

PURPOSE: The aim of this study is to explore whether urodynamics, with the addition of ambulatory urodynamic study (ambulatory-UDS), will be able to better predict and assess sacral neuromodulation (SNM) treatment outcome. Selection of patients is a critical element in achieving optimal outcome in SNM. Quantitative and qualitative results of urodynamic tests are used to justify surgical therapy and to evaluate treatment for lower urinary tract dysfunction. Therefore, these tests should be representative and subsequently offer a correct prognosis. METHODS: Between December 2002 until May 2013 selected patients with lower urinary tract symptoms (storage and/or voiding dysfunction) were included in an ambulatory urodynamic measurement database. From this database, the total subgroup of patients that underwent a sacral neuromodulation test evaluation was selected. RESULTS: A total of 98 patients were included. Success rate of SNM in patients with storage dysfunction was around 70 %, according to either conventional-UDS or ambulatory-UDS diagnosis. Based on conventional-UDS, success rate of SNM in patients with hypocontractility was 67 % and in acontractile patients 35 %. According to ambulatory-UDS diagnosis, success rates were 32 and 17 %, respectively. CONCLUSIONS: This study shows that conventional-UDS overestimates the amount of patients diagnosed with hypocontractile or acontractile bladder. Patients with reduced contractility on ambulatory-UDS have a lower chance of SNM success. Hence, ambulatory-UDS allows us to select patients with a real acontractile bladder and predict SNM failure. In patients with storage dysfunction, additional ambulatory-UDS does not seem to contribute in predicting SNM outcome.