Quadruple anal fistula:

Usually an anal fistula has an internal (primary) opening, an external (secondary) opening, and a tract connecting the two. Uncommonly the external openings are more than one but lead to a single internal opening. Rarely more than one internal opening is present, and, along with its corresponding external opening(s), it should be considered as a separate fistula. Injection of a dye to identify the internal opening may be considered when may external openings are present.