How do you get gallstones after are-section colon?

Gallstones: Depending on the type of colon resection (ie: partial colectomy vs. Total colectomy), you can have a change in your bile composition that would lead to gallstone formation. This would take a great deal of time (read: probably a few years). If you were diagnosed with symptomatic gallstones soon after surgery, it is likely you had them already.

Different animals: Having had a colon resection minimally increases your chances of gall stone disease in the long run. If you already had gall stones and did not eat or drink for days to a week after surgery your chances of an acute gall bladder "attack" are slightly higher. Gall stones form when the components of bile are not in balance and/or the gall bladder is not able to empty effectively.