This is an ethically approved randomised controlled study looking at whether Cystodistension(filling the bladder with fluid under pressure) provides any benefit over cystoscopy alone (looking in the bladder) in women with refractory overactive bladder. Urine samples will also be assessed for underlying infected cause of OAB using urinalysis, microscopy and culture and cytokine assays (In collaboration with the University of Kent). We hypothesize that Cystodistension has a therapeutic benefit to women with refractory OAB and the there is an increase prevalence in chronic urinary infections with raised cytokines in women with refractory OAB.