Anal Fistula

Do you experience intense pain in the anus, and notice blood and purulent discharge coming out of the orifice, or peri-anal area?

Does the pain and pus loss also coincide with fever, which does not seem to subside even with the use of antibiotics?

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You may be suffering from an infection known as an anal fistula: an abscess of the anal mucosa that, with no outlet, has created an artificial channel to the outside, from where purulent fluid exits.

Learn what anal fistula is and how it can be treated by reading this page written by Dr. Luisella Troyer.

What is an anal fistula?

In Proctology, an anal fistula is an infection carried by an abscess of a gland in the anal mucosa that, having no other outlet, has 'tunneled' outward into the skin, from which it continuously emits purulent material.

Basically, anal fistula is the final evolution of an internal mucosal abscess, which in turn originated from infection of a mucus gland.

The characteristic feature of anal fistula is precisely this incessant outward projection of pus, which is rather foul-smelling and continually soils the patient's underwear.

Like any abscess, the anal fistula swells the infected area, and causes great pain in the anus, so great that the patient resorts to the emergency room, in a state of total prostration.

What are the causes of anal fistula?

An anal fistula is the end of an abscess of a mucus gland, located in the dermis of the anal mucosa or perianal skin, and called Hermann's and Defosses' gland in medical jargon, in honor of its discoverers.

Having no external outlet, the infected gland swells abnormally with pus and bacteria, thus originating the abscess.

Fistulization is an extreme measure of the body, which, to limit the damage of the abscess, 'builds' an artificial channel to the outside with which to purge the purulent material.

At the present state of Medicine, the reason for this infection originating in the mucus glands is not yet clarified, but some autoimmune diseases, such as Crohn's disease, or infections such as diverticulitis or tuberculosis have been established as predisposing factors.

Repeated trauma, or classic disorders of alvus and defecation, such as constipation and chronic diarrhea, also seem to play an important role in the onset of infection.

In elderly or bedridden patients, the often common lack of adequate hygiene in the anal and perianal area appears to play an established role as a trigger for infection of Hermann's and Defosses' glands.

What are the symptoms of an anal fistula?

The main symptom of anal fistula is common to any other type of abscess (even dental abscess), and it is the extreme pain that afflicts the patient.

Often, such pain is reported as unbearable, and it does not recede even with the use of anti-inflammatories and antibiotics.

Acute pain, which causes exhaustion and sometimes despair in the patient, is often associated with fever.

The discharge of purulent, foul-smelling material from the fistula is another common symptom, a clear sign of subcutaneous abscess.

This pus, constantly gushing from the fistula, not infrequently causes localized dermatitis, which not infrequently gives rise to anal itching.

How is anal fistula diagnosed?

For the diagnosis of anal fistula, a proctological examination, accompanied by videoproctoscopy, is sufficient.

Generally, the diagnosis of fistula is relatively simple for the experienced Proctology Physician, but it is still necessary to accurately identify the internal pathway of infection.

To do this, the Physician can make use of an instrument called a speculum (basically, soft iron wire useful for following the path of the fistula to the root, that is, the infected gland).

The pathway can also be stained, during specillation, with blu methylene to better highlight the whole way to the infected root.

To complete the diagnosis and to prepare for therapeutic surgery, the Proctology Physician may also perform a 360° endoanal ultrasound.

This examination is very useful in understanding the exact path of the fistula, its possible branches its actual depth, with relative (if any) relationship to the sphincters.

Only in cases of further doubt, especially in complex situations, may the Proctologist prescribe a Nuclear Magnetic Resonance Imaging.

What is the therapy for anal fistula?

Therapy for resolution of anal fistula, as indeed in any other abscess, involves complete removal of the infected tissue, and remediation of the purulent area that is the source of the suppuration.

Thus, access is surgical: antibiotic-based drug therapy cannot resolve the infection, although it is often prescribed to limit the expansion of infected material.

Given that the symptoms of anal fistula are unbearable for the patient, surgery is often performed urgently.

Not surprisingly, fistula removal is the most frequent proctologic procedure performed in emergency.

There are various intervention and access techniques, which are often related to the location of the fistula and its degree of complexity, but any intervention must still ensure:

• The removal of all purulent material, down to the root of the infection (the infected gland);
  
• Respect for sphincter muscles, to avoid irreversible situations of fecal incontinence

One of the classic surgeries in surgery, which is still used, involves the removal of the infected gland and the application of a seton, that is, a kind of long, thin pad inserted into the fistula canal, which is progressively pulled over a few weeks during proctologic visits.

This expedient, which is actually centuries old (it was devised as early as the late 1300s by English Surgeon John of Arderne), is intended to slowly and progressively section the sphincter, with progressive healing sparing from fecal incontinence.

Alternatively to the setone technique, the Video Assisted Ana Fistula Treatment (VAAFT) technique has recently been introduced.

This is essentially a minimally invasive endoscopic technique: a small fistuloscope equipped with a camera and laser diode is introduced into the fistula, which is burned by the laser and closed transrectally.

Whatever technique is used and whatever surgical approach is chosen, it is imperative to emphasize that anal fistula removal surgery is always considered high proctologic surgery.

Even a minor error in surgery can result in permanent sphincter injury, thus compromising the patient's fecal continence.

Which Physician can diagnose and treat anal fistula?

The health specialist with great experience in anal fistula analysis and surgical treatment is the Proctologist Surgeon.

He is the one who has the skills, knowledge, and tools to treat anal fistula, and it is therefore to this professional that one should turn in any case of anal or peri-anal abscess.