Fistula, an abscess contracted to a narrow, hard, open passage in communication with, or in the immediate neighbourhood of, one of the mucous canals, lined by a kind of false membrane, giving rise to a thin discharge. There is salivary fistula, urinary fistula, &c.; but the most common and troublesome kind of all is the fistula in ano, in the lower bowel (see ANUS, RECTUM). The term is also applied to unnatural communications between two adjacent mucous canals (e.g. vesico-vaginal fistula), or between one of these and the external surface (e.g. gastric fistula, fecal fistula), independently of their size and shape. The treatment of fistula should only be entrusted to experienced surgeons.
For the cure of salivary or urinary fistula all that is generally necessary is to restore the patency of the natural ducts, which is done by passing instruments along them. Should a fistula, however, be situated where it is surrounded by muscular fibres, as at the orifice of the lower bowel, it is necessary to divide these, so as to leave the part at rest while nature repairs it. During the process of healing care must be taken that the wound closes from the bottom, otherwise the cut surfaces are apt to reunite, leaving the fistula unimproved. This may be secured either by stuffing the wound with lint, or by daily passing a probe or a finger along it to break down any adhesions that may have formed. Stimulant applications are also sometimes necessary to promote the healing process.
At times, however, fistulæ require more elaborate treatment, and are extremely difficult to close, especially those which result from loss of tissue between two adjacent mucous canals; fortunately, however, modern surgery is able to remedy these also. It is necessary to make the edges of the orifice once more raw, and to bring them in contact, but formerly the wound used rarely to unite, as the stitches produced such an amount of irritation. Now, however, by the use of silver-wire, or catgut, and by scrupulous attention to cleanliness, the parts can be kept together long enough to insure union; and thus, by the ingenuity of American surgeons, especially the late Marion Sims of New York, and others in Britain, certain diseases of women, arising from protracted labours, and formerly rendering the unfortunate subjects of them miserable and unfit for any of the duties of life, may be now remedied by a skilfully performed operation. See E. and E. W. Andrews, Rectal and Anal Surgery (2d ed. Chicago, 1889).
Fistularidæ. See FLUTE MOUTHS.