Dictionary.net

Generally occurs from some mechanical pressure or impediment. The principal indication in the treatment of these fistulae of the excretory canals being to put a stop to the constant discharge of the secretions, &c., through the preternatural channel, the fistulous passage is at times laid open, and a communication established with the natural excretory canal; at others, strong pressure is employed to procure its obliteration.

A fistulous tract by the side of the rectum. Those cases in which there is an opening of the f. by one or more mouths in the skin only, are called blind external fistulae; those in which there is an opening into the cavity of the intestine but none in the skin are called blind internal fistulae; those which have an opening both through the skin and into the intestine are called complete fistulae.