Have neurogenic bladder. I currently in trial phase of sacral stimulation. Last week my symptoms were perfect, today I again felt retention, why is that?

InterStim Adjustment. During the trial phase of interstim, some adjustments may be necessary. It is possible for the lead to move a little bit, which can alter the effectiveness of the nerve stimulation. You should call the device rep and ask them to help you adjust which position on the lead is stimulated and/or change the stim amplitude.
Interstim. Your temporary lead may have partially dislodged. Speak to your urologist about changing sides if two leads were placed.