Gallbladder problems or gallbladder disease occurs when the gallbladder doesn't empty properly.
Gallbladder disease usually is due to gallstones which block the exit of the gallbladder so it can't drain properly. If it continues to have difficulty draining, a lot of times the bile becomes almost stagnant and the gallbladder continues to swell, become inflamed, cause pain because it can't empty properly.
A person does not have to have gallstones to have gallbladder disease, sometimes it just more of a functional issue. Normally the gallbladder will empty approximately 35% in response to a meal, that can be measured with the HIDA scan, if the ejection for-action or percentage of emptying is less then 35%, that's a sign of gallbladder disease as well and that can be present without stones.