**2. Epidemiology**

Dyspepsia overall is a common symptom in the general population with reported prevalence rates ranging between 10-45% [12]. Such estimates are confounded by the use of differing criteria for defining dyspepsia as well as a recurrent failure to exclude patients who primarily report heartburn symptoms12. Nevertheless, dyspepsia remains a common issue with annual incidence rates estimated between 1-6%[13]. In the United States, there were 4,007,198 outpatient visits for gastroenteritis or dyspepsia and 130,744 hospital admissions for functional or motility disorders in 2009 [14]. This represents a 26% increase from the year 2000, which suggests an upsurge in the overall incidence of dyspepsia14.

*Epidemiology of functional gallbladder disease* (i.e.; Frequency of biliary pain with a normal appearing gallbladder e.g. without gallstones)

The true prevalence of biliary dyspepsia is unknown. Estimates are generally based on the presence of non-specific clinical features and a lack of structural findings on ultrasonographic investigation of the biliary system. In large Italian population-based studies, 7.6% of men and 20.7% of women experienced biliary pain yet lacked gallstones on abdominal ultrasonography [15, 16].

With the advent of minimally invasive surgery, biliary dyskinesia has become a new indication for laparoscopic cholecystectomy increasing 348% in adults [17] and escalating 700% in pediatric patients over approximately a decade [18]. Large scale case series now list biliary dyskinesia as the primary indication for cholecystectomy in 10-20% of adults [17, 19-22] and 10-50% of pediatric patients [23-26].

*Epidemiology of functional sphincter of Oddi disorders* (i.e.; Frequency of biliary pain after the gallbladder has been removed – postcholecystectomy).

In the US householder survey of presumably healthy adults, 69% expressed symptoms indicating a functional gastrointestinal syndrome within the previous three months and 1.5% had biliary dyspepsia following cholecystectomy [27]. Women were more commonly afflicted at 2.3% than men at 0.6% [27]. Nevertheless, sphincter of Oddi dysfunction (SOD) is uncommon in this population. SOD, when documented by ERCP manometry, occurs in less than 1% of the patients who have had their gallbladders removed and accounts for the abdominal pain in 14% of the patients with postcholecystectomy pain [28].
