An anal fistula is an inflammatory tunnel under the skin, connecting the anal canal and the surface of the surrounding skin. 80% occur as a result of an anorectal infection, wherein the anal crypts are infected and cysts containing pus form near the anal canal. If the abscess breaks or is opened a fistula is often formed.
These distinctions are based on the location and path of the fistula, which is seen above. This is called the Parks classification. Superficial fistulas are different from the other four in that the tracks are not linked to the anal canal or the sphincter, so are not included in the Parks classification. Anal fistulas can be described as simple or complex. Simple fistulas are low transsphincteric and intersphincteric fistulas. Complex fistulas describe any other type of anal fistula, which can take many shapes, sizes, depths, and can branch off.
Symptoms of an uninfected anal fistula can manifest as drainage from the opening of fistulas and itching around anus, and anal fistulas with infection cause fever and returning abscesses with a constant, throbbing pain, and the symptoms are exacerbated by movement, passage of stool, and coughing/sneezing. This can make rectal examination difficult without topical anesthetic, and even then many patients may not be able to tolerate it. In cases like this, where digital rectal examination is not possible or inconclusive, more advanced diagnostic methods may be necessary.
Treatment varies depending on the severity and location of the fistula. Antibiotics, antipyretics and, pain medication is prescribed if there is drainage (indicating abscess). For simple rectal abscesses, antibiotics are usually not needed. The surgical procedure for simple fistulas are called a fistulotomy or fistulectomy, where the fistula tract is cleared out or removed surgically and allowed to heal properly. For simple fistulas, success rate with fistulotomy is over 90%. More complex fistulas may be to twisted or branching for a fistulotomy so fibrin glue or fibrin plug may be used instead. Though in common, staged surgery may be needed.
With this condition, it is better to seek help sooner than later. Advanced abscesses that become complex are much more difficult to treat. For most however, it seems procrastination is not much of a problem- pain is a very effective motivator.