an abnormal passage from an abscess, cavity, or hollow organ to the skin or to another abscess, cavity, or organ
See fistula in American Heritage Dictionary 4
(fĭsˈchə-lə)
nounpl.fis·tu·las or fis·tu·lae(-lēˌ)
An abnormal duct or passage resulting from injury, disease, or a congenital disorder that connects an abscess, cavity, or hollow organ to the body surface or to another hollow organ.