Causes of fistula formation
Depending on their origin, fistulas are divided into congenital and acquired.
- Congenital fistulas are associated with embryonic developmental disorders (e.g., non-closure of the vitelline or urachal duct). Their characteristic feature is that the inner lining is always represented by epithelium.
- Acquired pathological fistulas develop as a result of inflammation, trauma (mechanical, chemical, radiation), organ wall ischemia, abscess rupture, or tumor breakdown.
- Acquired artificial fistulas are stomata (gastrostomy, colostomy) surgically created for diversion of contents.
Types of fistulas by wall structure
The anatomical structure of a fistula determines its healing capacity:
- Granulating fistulas. The walls are covered with granulation tissue. They occur due to inflammation or trauma. Their main feature is the ability to undergo spontaneous closure if the underlying cause is eliminated (e.g., establishing bile outflow or removing a foreign body).
- Epithelized (tubular) fistulas. They have a long tract lined with epithelium. These are most often congenital pathologies. They do not close on their own.
- Labial fistulas. There is no tract. The mucous membrane of the organ (e.g., intestine) fuses directly with the skin, forming a lip-like structure. They are characteristic of intestinal stomas and require surgical closure.
Classification of labial fistulas by function
Labial fistulas of hollow organs (most commonly intestinal) are divided into:
- Complete: all organ contents are discharged outward. This occurs due to the formation of a spur — a protrusion of the posterior intestinal wall into the fistula lumen that completely blocks the outflow into the distal sections.
- Incomplete: organ contents are only partially discharged through the fistula, while the rest passes further down the natural pathway.
Diagnostics and treatment
The main sign of an external fistula is the discharge of organ contents outward. To clarify the diagnosis, fistulography (contrast administration into the fistula tract) and endoscopy are used.
Treatment depends on the type of fistula:
- Granulating fistulas may heal conservatively with adequate drainage and sanitization.
- To protect the skin from aggressive discharge (maceration), zinc paste (Lassar's paste), polymer films, and adhesives are used.
- For temporary defect closure, obturators are used to prevent the loss of contents and restore intestinal passage.
- Epithelized and labial fistulas are cured only by surgical excision of the tract and closure of the organ defect.
Briefly: answers to topical questions
What instrumental diagnostic methods are used to examine fistulas?
Instrumental diagnosis of fistulas involves probing, radiological, and endoscopic methods.
- Probing is the exploration of fistulous tracts.
- Radiological methods include fistulography with contrast agent administration into the fistulous channel and contrast radiography of the gastrointestinal tract.
- Endoscopic methods include fistuloscopy, gastroscopy, colonoscopy, bronchoscopy, and cystoscopy to determine the localization and size of the orifice.
What are the methods for surgical closure of labial intestinal fistulas?
Radical surgical interventions are used for the surgical closure of labial intestinal fistulas, as they have no tendency toward spontaneous closure.
- Fistula excision is the complete removal of the pathological tract.
- Suturing of the orifice is the closure of the defect directly in the wall of the affected organ.
- Organ resection is the partial removal of the organ bearing the fistula (performed in certain cases).
What systemic complications are caused by a long-standing complete intestinal fistula?
A long-standing intestinal fistula can lead to water-electrolyte balance disorders and dehydration.
- Dehydration manifests as dry skin and tongue, reduced tissue turgor, severe thirst, and soft eyeballs.
- Hemodynamic signs include tachycardia, decreased hematocrit, and central venous pressure (CVP).
- Renal manifestation is a decrease in urine output (oliguria).
What are the causes of internal inter-organ fistulas?
Internal inter-organ fistulas form as a result of mechanical trauma, chemical or radiation exposure, surgical complications, and destructive processes.
- Destructive processes include purulent melting of the wall, ulceration, and breakdown of a malignant tumor; an abscess may rupture into the lumen of another organ.
- Mechanical trauma can occur during endoscopy, bougienage, probing, or damage by foreign bodies.
- Surgical complications are associated with direct organ trauma or disruption of its blood supply followed by necrosis.
- In Crohn's disease, fistulas can connect the intestine to the urinary bladder, vagina, or another intestinal loop.
To remember which fistulas heal on their own, associate granulations with "construction" — tissues are actively recovering (granulating fistulas close). Epithelium, on the other hand, is "finished decoration"; the body considers the work done (labial and epithelized fistulas do not overgrow on their own).
Class and exam questions
How does a lip-like fistula differ from a tubular fistula?
A labial fistula has no tract: the organ's mucosa transitions directly into the skin. A tubular fistula has a distinct tract between the organ and the body surface.
Why does the intestinal contents not pass further down the bowel in a complete lip-like fistula?
Due to the formation of a spur — prolapse of the posterior intestinal wall into the fistula lumen, which mechanically blocks the distal intestine.
Which fistulas can close without surgery?
Only granulating fistulas. When the cause of inflammation is eliminated, granulations fill the tract, mature into scar tissue, and obliterate the channel.
What else to study on this topic
- Pathogenesis of primary multiple fistulas in actinomycosis
- Specific dye (indicator) tests for diagnostics
- Radiological signs of internal organ fistulas
- Chemical methods of skin protection around a stoma
- Umbilical fistulas: differential diagnosis of the vitelline duct and urachus
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