The Gallbladder Function after Gastric Bypass Surgery - Trial

Obesity is a growing problem with many adverse effects on human health. The
Roux-en-Y Gastric Bypass has been an effective method to treat obesity. The
long-term mortality decreases in the treated population. The incidence of
gallbladder pathology is increasing after a RYGB procedure . Changes in
cholesterol saturation of the bile, increased crystallizing factors, and a
deterioration of the gall bladder function are likely to be the cause of this
increase in gallbladder pathology. Several studies have been conducted on this
subject, but several questions remain.

Primary Objective: To assess the impact of RYGB on gallbladder function (during
a follow-up interval of 1 year). We will assess the fasting volume, the
ejection fraction and the residual volume of the gallbladder. In addition, we
will compare serum cholecystokinin levels before and after RYGB.
Hypothesis: We expect that gallbladder function will decrease (decreased
ejection fraction, increased residual volume and fasting volume) during
follow-up after RYGB.

Secondary Objective(s):
1 To evaluate the number of patients that will develop sludge or gallstones
after a RYGB
2 To determine in which time-frame most gallstones will develop
3 To assess if gallstones development is correlated with a change in
gallbladder function
4 To assess if the amount of EWL correlates with a change gallbladder function
5 To define causes of impaired function, eg is this CCK mediated or is nervus
vagus damage contributing.
6 To predict gallstone development in the RYGB patient population

An observational case-control study will be conducted at the Maasstad Hospital,
Rotterdam. Patients will be included from the bariatric outpatient clinic
during their intake visits. The gallbladder function of the subjects will be
assessed two weeks prior to and 6 and 12 months after their RYGB. Together with
the ultrasonographic assessment serum cholecystokinin levels will be determined.
After 12 months of follow-up data collection will be completed and statistical
analysis of the data will be conducted.

The burden on the subject is low. The ultrasound will take place in the morning
so the fasting period will be an overnight fast. The test meal carries no risk.
The venous puncture is common practice, which hardly involves any risks.