Hi, I've Just Had A Ultrasound Of The Abdomen And

Hi, I've just had a ultrasound of the abdomen and they found a single mobile calculus with cholelithiasis. The remainder of the examination defined satisfactorily with the common bile duct not dilated measuring 2mm. The kidneys, pancreas and liver define within normal Limits as does the spleen. I was told I can have surgery to remove the gall bladder with the stone or just leave it, follow a proper diet and have it reviewed in 12 months. My question is: why can't they just remove the single calculus? Obviously the calculus will be bigger in 12 months ... Doesn't that pose more of a problem with surgery being more complicated? I don't want to remove the gall bladder .. Just the calculus. And I don't want to wait and run the risk of getting complications. Isn't there anything they can do to dissolve the calculus? I'm confused, not sure what I should do. I value your opinion.