A fistula is an abnormal connection between two epithelized surfaces. Fistulas can form between any two hollow spaces including blood vessels, intestine, vagina, bladder, and skin. There are three different categories used to define a fistula, anatomic, physiologic, and etiologic. Anatomically, fistulas are subdivided into two categories, internal and external. Internal fistulas are connections between two internal structures. A few examples of an internal fistula would be enterocolic, ileosigmoid, and aortoenteric. Alternatively, external fistulas form connections between an internal structure and external structure. Examples of this would be enterocutaneous, enteroatmospheric, and rectovaginal fistulas. When categorized physiologically, the fistula is differentiated based on fluid output. Low-output fistulas drain less than 200 ml of fluid per day, high-output fistulas drain greater than 500 ml of fluid per day, and medium-output fistulas fall between the two. Etiology is the last way in which fistulas are categorized. Common etiologic categories are traumatic fistulas, surgical site fistulas, and fistulas associated with Crohn's disease. This article will specifically cover fistulas that fall under the anatomical category of enterocutaneous fistulas.