Abscess and Fistula. Anal abscess and fistula can be described together because of their relationship. One creates the other. Abscess about the rectum is simply a boil-like process at the outlet of the anus, and its drainage tract from the inside of the rectum, out through the skin about the anal opening, is called a fistula.
An anal abscess produces an intense throbbing pain about the supersensitive anus region. This pain is not related to bowel movement, but becomes intense under any pressure, as in sitting. The abscess is caused by fecal material infecting the wall of the rectum and it looks much like a boil. It is reddened, swollen and hardened beside the anal opening, and may grow so large, the anus appears crowded off to one side.
Fig. 125. Fistula formation begins with infection perforating the rectal wall. This brings about abscess or boil formation, which in turn heads and ruptures through the outer skin at a distance from the anal opening. Instead of healing, the entire tract thus established continues to act like another anal outlet.
Relief from the intense pain of an anal abscess is eagerly sought because the sufferer is usually disabled for any other activity. There is temporary relief with sitting in warm water, but permanent relief is obtained only by drainage of the abscess. This is effected either by the abscess heading and draining itself, or through an incision and drainage operation.
Anal fistula, we have seen, results from an abscess about the anus. After drainage, the abscess collapses into a string-like channel. If fecal material continues to reinfect this small channel, there is continual formation of pus to drain out through the skin. Thus is a fistula born.
Fig. 126. An external fistula appears as a small pimple constantly draining in the anal region. It usually forms following an abscess which has drained. An anal fissure is an infected crack in the skin, similar to a crack in the mouth.
A fistula looks like a small red pimple in the skin close to the anus and usually does not produce much pain. Most of the soreness present is due to soreness from the continual irritating drainage on the surrounding skin. If the anal fistula heals over on the outside, the oncoming pus forms another abscess which soon penetrates the skin once more to restablish the fistula. While localized heat applications are of temporary value in reducing irritations, they can do very little in the way of permanent results. This disease must be surgically treated in a special manner to prevent its recurrence.