Patients undergoing endoscopy will be diagnosed on endoscopic visualization and pathological examination. Your gastroenterologist may take small tissue samples (biopsy) to look for infection, illness, and early signs of cancer. These samples may come from the esophagus, stomach, small intestine, or colon. Gastroenterologists may also remove polyps along the GI tract. Histopathologic evaluation is helpful to differentiate malignant, inflammatory and infectious processes. Therefore, biopsies should be taken of any suspect tissue or as a follow-up to an earlier endoscopic procedure to evaluate prior therapy.