surfaces approximated with stitches.

The _tuberculous sinus_ is described under Tuberculosis.

A #fistula# is an abnormal canal passing from a mucous surface to the
skin or to another mucous surface. Fistulæ resulting from suppuration
usually occur near the natural openings of mucous canals--for example,
on the cheek, as a salivary fistula; beside the inner angle of the eye,
as a lacrymal fistula; near the ear, as a mastoid fistula; or close to
the anus, as a fistula-in-ano. Intestinal fistulæ are sometimes met with
in the abdominal wall after strangulated hernia, operations for
appendicitis, tuberculous peritonitis, and other conditions. In the
perineum, fistulæ frequently complicate stricture of the urethra.

Fistulæ also occur between the bladder and vagina (_vesico-vaginal
fistula_), or between the bladder and the rectum (_recto-vesical
fistula_).

The _treatment_ of these various forms of fistula will be described in
the sections dealing with the regions in which they occur.

_Congenital fistulæ_, such as occur in the neck from imperfect closure
of branchial clefts, or in the abdomen from unobliterated fœtal ducts
such as the urachus or Meckel's diverticulum, will be described in their
proper places.


CONSTITUTIONAL MANIFESTATIONS OF PYOGENIC INFECTION

We have here to consider under the terms Sapræmia, Septicæmia, and