Will I need my gallbladder out?

I'm a 28 year old female. Normal to slightly underweight. I had an ultrasound done to test for gallstones and it showed i do have some. I do get bad pains after i eat and at night. But, the Dr left a message today asking for me to come in for a stool sample. Why would a stool sample be needed? Also, if i have have a partial right sided colectomy, would it effect the gallbladder removal? If i have scar tissue would an open surgery be needed over laproscopic? I know i can ask the Dr this, i just want to be prepared