Gastro not my area of expertise, but I will weigh in since no one else has.
Once you state "extended incision", I will assume the remaining portion was done open. If that is the case, you would code as open. If my assumption is incorrect and they only extended the incision to get a better look and did the colon transection and anastomosis laparoscopic, then you would code as laparoscopic.
From GYN examples: lets say a patient is having a total hysterectomy (removing uterus & cervix) and bilateral salpingo-oophorectomy [BSO](removing tubes and ovaries). If they perform lap BSO but then due to extensive adhesions, or a bowel injury, etc., open the patient and perform the hysterectomy, this is all coded as open only since that is how the procedure ended up. Sometimes, they will perform the entire procedure laparoscopic, but due to an enlarged uterus or various anatomy issues, they may enlarge the incision just to remove the specimens. Or perhaps might enlarge the incision if there is a bleed they can't see well laparoscopically. As long as the surgery is done laparoscopic, that is what you code.
