Fistulas and sinus tracts are hallmarks of Crohn’s disease, affecting approximately 20–40% of patients [7]. The morphology and anatomic sites of fistulas are protean: enteroenteric, enterocolic, colocolic, enterovesical, enterovaginal, enterocutaneous, anorectal, duodenopancreatic, gastrocolic, colobronchial, and enterospinal [48–54].
Source: wiktionary