The goal of this observational study is to learn about the impact of ursodeoxycholic acid treatment on the gallbladder polyp evolution in patients with gallbladder polyps that undergo follow up. The main question it aims to answer is:

• Whether ursodeoxycholic acid could decrease the gallbladder polyp size and therefore spare unnecessary follow up or surgical interventions

Participants will be managed according to the standard practice of the department they are attended:

• According to the established practice in the Department of Surgery, patients that either do not have an indication for cholecystectomy or decline the offered intervention, and are subjects for a follow up, are usually prescribed Ursodeoxycholic Acid, at 10-15 mg/kg/day for at least 6 months.
• According to the standard practice of Gastroenterology Department, patients are followed up according to the published guidelines.

Researchers will compare the groups that receive or not ursodeoxycolic acid treatment to see if the polyp size evolution differs significantly.

Gallbladder polyps are common findings on abdominal ultrasound studies. Most of them are cholesterol polyps. However, often they require a prolonged follow up due to impossibility to efficiently rule out the presence of a real adenomatous polyps with potential of malignization.

Ursodeoxycholic Acid is a well-studied and long known drug that has been used for conservative treatment of bile stones with high cholesterol concentration (most of them), but also for bile sludge and gallbladder polyps, that are considered precursors of the gallbladder stones. It has been found in several studies that prevent from recurrent idiopathic acute pancreatitis and from gallbladder stone formation after gastric (including bariatric) surgery.

Participants will be managed according to the standard practice of the department they are attended:

• According to the established practice in the Department of Surgery, patients that either do not have an indication for cholecystectomy or decline the offered intervention, and are subjects for a follow up, are usually prescribed ursodeoxycholic acid, at 10-15 mg/kg/day for at least 6 months.
• According to the standard practice of Gastroenterology Department, patients are followed up according to the published guidelines.

Researchers will compare the groups that receive or not ursodeoxycolic acid treatment to see if the polyp size evolution differ significantly during the studied period of 1 year. The small size changes could have a great impact on the management of the gallbladder polyps as for a 2mm increase could be a reason to indicate a surgical intervention and a 2mm decrease could cause the discontinuation of the follow up.

Inclusion Criteria:

• Patients with gallbladder polyps eligible for standard follow up (without indication for cholecystectomy or patient decline surgery or polyps < 5mm without risk factors such as age>60 years, primary sclerosing cholangitis, asian ethnicity, sessile polypoid lesion)

Exclusion Criteria:

• Patients with gallbladder polyps that received ursodeoxycolic acid doses lower than 10mg/kg/day

Consecutive patients referred for an outpatient consultation to the Departments of Surgery and Gastroenterology due to gallbladder polyps.