**1. Introduction**

Overactive bladder (OAB) is a disturbance of filling/storage and has been defined by the International Continence Society as "a symptom syndrome consisting of urgency with or without urge urinary incontinence, often associated with urinary frequency and nocturia." (Abrams et al., 2002) OAB has been divided into OAB without urinary incontinence (OABdry) and OAB with urinary incontinence (OABwet). The reported prevalence of OAB in women varies between 7.7 and 31.3%, and increases with age. (Irwin et al., 2006a; McGother et al., 2006;Milsom, et al., 2001; Stewart et al., 2003; Wagg et al., 2007)

The symptoms of OAB include urinary urgency, urinary frequency, nocturia, and urinary urge incontinence. These symptoms often remain undetected and undertreated by both the woman and her providers, despite the substantial impact on a woman's quality of life. (Griffiths et al., 2006; Mardon et al., 2006) In a multiethnic survey, only 45 percent of women who reported weekly urinary incontinence sought care for their incontinence symptoms. (Harris et al., 2007) This leaves incontinent women with psychological morbidity and a diminished quality of life. (Irwin et al., 2006b)
