Anal abscesses and fistulas: how to choose the best approach?

Anal abscesses and fistulas: what is it?

Abscess and anal fistula must be considered in most cases only one disease: the suppuration of a cryptic gland of the anal canal which generally evolves in three stages. In the first stage the abscess originates in an infected gland and opens in the crypt constituting the internal orifice; in the second one there is the extension in the inter-sphincter spaces and while the third, terminal stage is that of opening on the skin through the external orifice.

If the internal and external orifice are a constant of all the fistulas, the passage of these through the anal sphincters is very variable and this makes a fistula a trivial disease or a true major pathology.

From a clinical point of view, abscesses and fistulas behave extremely differently, in fact, abscesses are a surgical emergency with acute stabbing pain generally associated with perianal swelling and fever, while fistulas are more or less annoying chronic infections, characterized by the presence of pus that stains undergarments associated with itchiness or not.

How is the diagnosis made?

Both diagnoses of these conditions are clinical and are formulated through the execution of an outpatient proctological examination and, possibly, an anoscopy . For the identification of the fistula route we have two techniques:

  • Transanal ultrasound with 360 ° rotating probe: this examination has an accuracy percentage of 80-89%, which can increase up to over 90% if using hydrogen peroxide as a contrast
  • Magnetic Resonance: more expensive analysis, indicated in more complex cases.

How to cure a perianal abscess?

The conservative approach with the use of antibiotics represents a possible alternative to the surgical drainage of pus but applicable only in cases of small and shallow abscesses. The only therapy to resolve an abscess is to incise the overlying skin so that pus can drain out. This incision can be made on an outpatient basis, but in most cases surgery with deep sedation is required.

And what about perianal fistula therapy?

The type of intervention is strictly connected to the complexity of the fistula route in particular from:

  • Height of the internal anal orifice;
  • Number of journeys;
  • Amount of anal sphincter involvement.

So the surgical possibilities can be summarized as follows:

  • Simple fistulotomy: procedure indicated in the case of single submucosal fistulas affecting a reduced portion of the sphincter. It foresees the incision and the flattening of the fistula with consequent healing of the wound from the inside to the outside (by “second intention”);
  • Fistulotomy on bristle: it is still the most used operation to resolve fistulas involving anal sphincters (sphincter tran). This technique requires treatment in several stages to avoid damage to the anal sphincter and therefore faecal incontinence. The procedure involves in the first phase the positioning of a drainage or bristle in the fistula (after identification) which will be tensioned at time intervals, during the outpatient visits, so as to be able to slowly sever the anal sphincter and allow a gradual healing without damaging the sphincter apparatus. If a bristle is used, the treatment will last a few months but the patient will still be able to carry out normal daily activities;
  • Injection of fibrin glue through the fistula: even with this technique muscle tissue is not compromised, on the other hand it has a recurrence rate that exceeds 50%;
  • Advancement flap: it is a more complex technique but which is indicated in case of “high” fistulas, for which the times of the bristle would be too long. It involves performing a fistulectomy, repairing the sphincteric breach and covering the muscle plastic of the anal canal with a mucosal and submucosal flap of the rectum which is followed from within;
  • VAAFT (Video assisted anal fistula treatment): an endoscopic method is used to identify the fistula and once cannulated, cauterization of the fistula is carried out from the inside and the closure of the internal orifice by transanal. We are still waiting for the results of the studies on this technique, but the results are promising;
  • LIFT (Ligation of intersfinteric fistula tract): in this approach we try to interrupt the fistulous passage in its passage between the internal and external sphincter. In practice, after identifying and opening this inter-sphincter space, the ligature and section of the fistula is carried out. Such an error technique . Invalid hyperlink reference. preserves the integrity of the internal and external anal sphincters which are delicately spread apart.


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