Fistulas

Definition

By "fistula" s "we mean an abnormal canaliculus, of a purely pathological character, which can put two internal organs or an internal cavity in communication with the skin (external). In general, fistulas are the final result of severe inflammation, a in turn caused by an abscess (complicated and pus-rich infection) which, when bursting, originates a tubular connecting path.

Although fistulas, by definition, are considered pathological passages, they can sometimes be created for various therapeutic reasons.

Causes

Most of the time, fistulas are the final outcome of severe trauma or infection which progresses to ABSCESS. The inflammation that derives from the lesion gradually involves the neighboring anatomical structures, thus originating adhesions between tissues. Being a purulent infection - that is, rich in pus (creamy fluid composed of bacteria, cell debris, plasma and white blood cells) - the abscess it tends to burst to pour out its contents: in doing so, a passage is created (called a fistula) which acts as a link between the center of the infection and the surrounding tissues.
Among the main causes of fistulas linked to inflammatory phenomena we cannot forget Crohn's disease, often responsible for anorectal fistulas (which connect the rectum or an "other anorectal site with the skin) and enterocutaneous (between the intestine and the skin).
But inflammations are not the only causative factors of fistulas: these anomalous pathological paths can in fact be induced by a badly made SURGICAL INTERVENTION.

Examples

1. An "improperly performed gallbladder operation can favor the development of biliary fistulas (which, for example, connect the bile ducts to the skin);
2. A poorly done tracheostomy can cause tracheoesophageal (between the esophagus and trachea) fistulas.

Other types of TRAUMAS can instead generate fistulas of another nature, such as recto-vaginal or vesico-genital ones. These variants of fistulas have been observed in numerous women who have experienced rape.
Furthermore, a particularly complicated and long TRAVEL can cause obstetric fistulas (pathological connection between the vagina and the bladder / urethra / rectum, see image on the side): it is an extremely dangerous birth complication for both the unborn child and the mother. In fact, according to the site in which the obstetric fistula originates, the woman undergoes a severe and continuous urinary and / or fecal incontinence. The unborn child dies in most cases.

Deepening
Obstetric fistulas arise due to extremely difficult and prolonged labor in which the baby's head remains in the vagina for such a long time that it induces necrosis (death) of adjacent tissues (as marked by the blue stroke and surrounded in red). Due to necrosis there is a loss of correct separation of the surrounding anatomical structures, with the onset of an "abnormal communication between the genital and urinary tract or, more rarely, between the genital and intestinal tracts.

Types of fistulas

There are innumerable types of fistulas, essentially classified on the basis of the area in which they arise, the position, their structure and the triggering agent.
Given the numerous variants, to facilitate understanding and facilitate memorization, the table shows the classification criteria for fistulas.

Classification of Fistulas according to the structure Classification of Fistulas based on location Classification of Fistulas by Cause

• SIMPLE FISTULAS: presence of a single communication channel
• RAMIFIED FISTULAS: presence of multiple communication channels (they are the result of new tubular ducts originating from old fistulas that have recreated abscesses)
• COMPLETE FISTULAS: they connect two internal organs
• INCOMPLETE FISTULAS: absence of a real communication between cavities (they have an "opening towards the outside", which however does not connect with internal organs because the other end has spontaneously closed)
• HORSESHOE FISTULA: typical of the anus, this canaliculus connects the anal sphincter to the surface of the skin, first passing through the rectum

• EXTERNAL FISTULAS: the canaliculus connects an organ with the skin
• INTERNAL FISTULAS: they bring two internal organs into contact

• Trauma fistulas (including surgical ones)
• Abscess fistulas
• Congenital fistulas
• Fistulas from inflammatory bowel diseases
• Labor induced fistulas
• Therapeutic fistulas

We also remember that fistulas can manifest themselves in an acute form or, in the most serious cases, become chronic: in the latter case, the fistula persists because it is continuously fed by the pathogens involved in the infection (which produce exaggerated quantities of pus). In still other cases, especially in urogenital fistulas, the connecting canaliculus can take on a chronic course because biological fluids (eg urine, faeces) continue to pass into the affected tissue / organ.

Common fistulas and localization

Fistulas can hypothetically appear in any area of ​​the human body, involving almost all internal structures. In any case, by examining the medical statistics, it is possible to identify the fistulas that most frequently affect men:

• Circulatory system fistulas (eg pulmonary arteriovenous fistula, in which the canaliculus connects an "artery and a blood vein)
• Digestive tract fistulas (e.g. stomach and duodenal fistulas)
• Fistulas of the urogenital tract (e.g. urethral fistula, rectovaginal fistulas)
• Respiratory system fistula (e.g. tracheoesophageal fistula)
• Fistula of the eyes and adnexa (e.g. lacrimal fistula, mastoid fistula, periauricular fistula)
• Dental fistula (pathological canaliculus that connects the center of dental inflammation / infection with a neighboring tissue such as the mucosa, skin or alveolus

Therapeutic fistulas

As mentioned, some fistulas are created specifically by surgery, to satisfy certain therapeutic purposes. This is the case of patients suffering from severe renal insufficiency, undergoing "extracorporeal hemodialysis: in this category of subjects, the surgeon provides the patient's arm with an arteriovenous fistula called Cimino-Brescia. More precisely, the doctor creates a connection (fistula) between the cephalic vein and the radial artery of the arm in order to facilitate the collection of blood for hemodialysis therapy.