Thank you for the question.
There are several possible causes of fluid around the gallbladder. The fluid around the gallbladder is frequently related to inflammation or infection. The fluid can also be related to the presence of a tumor compression the bile duct, but it should have been present on previous scans. It also could be related to a leakage of bile. The fact that you have a stent in the duct does increase the risk for infection. Ultimately, your physician will correlate the CT findings with other clinical findings to clarify the diagnosis.