It is true that the only effective treatment for gallbladder
polyps is removal of the gallbladder. However, it depends upon the situation.
First, surgery should be considered if there are gallstones along with the polyp - since this increases the risk of cancer.
If gallstones are not found, polyps larger than 10mm should have surgery performed. Smaller than 10mm should have close ultrasound
followup. Repeat ultrasound in 3-6 months, then yearly afterwards can be considered.
Since in your case the size of polyp is bigger than 10 mm,you may opt for gall bladder
Consult your doctor for the final opinion.