ABC Medical Center > Anal fistula

What is Anal fistula?

21:54 - 4 May , 2021


This condition is caused by the blockage of an anal gland, causing an abscess that tears the tissue of the perianal area, producing a connective anomaly (forming a tunnel) that leads to a dysfunction in the evacuation processes, causing burning and itching. If it becomes infected, the fistula can cause serious complications and promote the appearance of some systemic condition.

More than half of abscesses are likely to become fistulas if not treated properly, although there are also less common fistulas that are not caused by abscesses, but are the result of other disorders such as sexually transmitted infections, diverticula, cancer, tuberculosis, or Crohn’s disease.

Classification of anal fistulas according to their location:

  • Suprasphincteric.
  • Extrasphincteric.
  • Intersphincteric.
  • Transsphincteric.
  • Subcutaneous.

Signs and symptoms Anal fistula

  • Frequent appearance of anal abscesses.
  • Swollen and sore anus.
  • Painful defecation.
  • Anal bleeding.
  • Purulent fluids.
  • Skin burning around the anus.
  • High fever.
  • Tiredness.
  • Weakness.

If you experience any of these symptoms, go to your doctor immediately to receive a timely diagnosis and treatment, thus avoiding possible complications.

Diagnosis and treatment Anal fistula

Once your doctor analyzes your symptoms and clinical history, they will perform a physical examination that includes an exhaustive observation of the outer area of the anus in search of possible skin openings through which secretions drain, trying to establish their orientation and level of depth.

In case the fistula cannot be seen externally, an anorectal endoscopy will be necessary, as well as an ultrasound and an MRI to clearly identify the fistula, its magnitude, and direction.

When diagnosing the fistula, it should be ruled out that its appearance is not due to conditions such as Crohn’s disease, since it is necessary to treat the underlying disease in parallel. For this reason, they will order blood tests, X-rays, and a colonoscopy.

When confirming the diagnosis, the treatment to follow will be a fistulotomy, which is a surgical repair according to the fistula’s level of depth and length, where a cut is made of the tissues that cover the tunnel, turning it into an open channel.

When it comes to a large fistula, it will be necessary to place a drainage seton for a couple of months, which allows the pus to be expelled.

Although most of these surgeries are outpatient, when it comes to extensive and complex fistulas, the patient must remain hospitalized for two or three days.

Post-surgery treatment includes the intake of laxatives for one or two weeks to facilitate bowel movements and avoid additional efforts in the affected area, as well as some painkillers to control post-surgical pain.

At ABC Medical Center’s Internal Medicine Department, we offer health care services with the highest quality and safety, from the prevention, diagnosis, timely treatment, and monitoring of infectious, respiratory, endocrinological, dermatological, rheumatic, nephrological, gastrointestinal, and hematological pathologies of both chronic-degenerative diseases and acute conditions, through a comprehensive and multidisciplinary model.


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  • Amarillo HA, Manson R, Fourcans S, et al. Factores de riesgo y análisis de la recurrencia en el tratamiento quirúrgico de la fístula anal. Enfermedades del Ano, Recto y Colon. 2011;17(1):10-16.
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