Anatomy and classification of fistulas
Pararectal fistulas are pathologically formed tracts in the soft tissues surrounding the rectum. The anatomical structure of these formations can be quite diverse: in practice, they may have one or even multiple external and internal openings. In addition, an entire branching network of fistulous tracts extending into the pararectal cellular tissue often forms.
To systematize diagnoses and choose treatment tactics in operative surgery, a clear classification is used. Globally, all pararectal fistulas are divided into two large groups:
- Complete fistulas. These are through pathological tracts that connect the lumen of the rectum with the skin. This group includes:
- Complete external fistula: a through tract that directly connects the rectal lumen and the skin surface.
- Complete internal fistula: in this case, the fistulous tract communicates exclusively with the lumen of the gut (both openings are internal, without reaching the skin).
- Incomplete fistulas. These are blind tracts that open on one side only.
- Incomplete external fistula: the pathological tract opens only onto the skin, without penetrating the rectal lumen, ending blindly in the tissues (blind tract).
- Incomplete internal fistula: the fistulous tract originates from the rectal lumen and ends in a blind pocket within the pararectal tissue.
Preoperative diagnostics
High-quality and comprehensive preoperative preparation is an absolute guarantee of successful surgical treatment. Before surgery, the operating surgeon needs to obtain the most accurate and exhaustive information about the topography of the pathological process.
As a rule, fistulography—an examination of the fistulous tracts to assess their direction and extent—is mandatory during the preparation stage.
Directly for the visualization of fistulous tracts during the surgery itself, the method of staining the fistula walls is used. A methylene blue solution is used as the primary dye. The introduction of methylene blue into the fistula allows for clear contrasting: the stained tissues stand out well, enabling the surgeon to visualize the entire tract, discover all its branches and internal openings.
Surgical treatment methods
The key anatomical factor that strictly determines the choice of a specific surgical procedure is the precise topographical position of the fistulous tract. Specifically, the localization of its external and internal openings relative to the muscle fibers of the anal sphincter is assessed.
The most important rule of pararectal fistula surgery: during any intervention, damage to the sphincter must be categorically avoided. Preserving the integrity of this muscular apparatus is critical for maintaining its normal function.
The surgeon's arsenal includes several approved methods of surgical treatment:
- Fistulotomy. A basic intervention aimed at opening the tract lumen.
- Fistulectomy. Radical removal of pathological tissues; in surgical practice, this technique is known as the Gabriel procedure.
- Mucosal advancement and rotation. A plastic surgical method for defect closure.
- Seton placement. Gradual transection of tissues.
- Separation of the rectal lumen from the fistulous tract. This approach is known as the Blinichev operation.
Briefly: answers to topical questions
How are pararectal fistulas classified in relation to the anal sphincter fibers?
In relation to the anal sphincter muscles, pararectal fistulas are classified according to the Parks system. This classification is based on the anatomical relationship of the fistulous tract to the muscular structures. The following types of fistulas are distinguished:
- Trans-sphincteric (trans-sphincteric) — a type of fistula according to the Parks classification.
- Intersphincteric (intersphincteric) — a type of fistula according to the Parks classification.
- Suprasphincteric (suprasphincteric) — a type of fistula according to the Parks classification.
- Extrasphincteric (extrasphincteric) — a type of fistula according to the Parks classification.
Accurate determination of the fistula type is extremely important, as the choice of surgery depends directly on the position of the fistulous tract relative to the sphincter, and during surgical intervention, muscle damage must be avoided to preserve their function.
What instrumental methods are used for the preoperative diagnostics of pararectal fistulas?
The following methods are used for the preoperative diagnostics of pararectal fistulas:
- Endosonography — clearly visualizes fistulous tracts passing within the sphincter and the internal opening of the fistula.
- Magnetic resonance imaging — the method of choice for diagnostic imaging; preoperative MRI reduces the recurrence rate in complex forms of fistulas.
- Fistulography — used in preoperative preparation and is mandatory for fistulas with fluid collections.
- Probing of the fistulous tract — determines the direction of the tract and its relation to the sphincter.
- Administration of methylene blue — used for contrasting and visualization of the fistulous tract.
What is the essence of the Blinichev operation?
The essence of the Blinichev operation is the separation of the rectal lumen from the fistulous tract. This method is used in the surgical treatment of pararectal fistulas. The choice of this operation, like other surgical methods, depends on the position of the fistulous tract relative to the sphincter, specifically the location of the external and internal openings. When performing the intervention, it is extremely important to avoid damaging the sphincter to preserve its normal function.
In which types of pararectal fistulas is the seton method indicated?
The use of the seton method (placement of latex drain-setons) is indicated in the majority of cases for trans- and extrasphincteric pararectal fistulas. Additionally, the use of a draining latex seton is recommended for adequate drainage of fluid collections in complex fistulas, for example, in Crohn's disease. A mandatory condition for the safe application of this method is the clear localization of the internal fistula opening.
What is the essence of the plastic surgical method for treating pararectal fistulas?
The essence of the plastic surgical method for treating pararectal fistulas lies in the excision of the fistula followed by plasty of the internal fistula opening. In the absence of an acute inflammatory process in the rectal mucosa, advancement of the musculomucosal flap of the rectum is performed to close the defect. In the classification of surgical methods, this surgical approach is also described as mucosal advancement and rotation.
To avoid confusing the types of incomplete fistulas, rely on the name: "external" means the opening is only on the outside (on the skin), and "internal" means the opening is only on the inside (in the rectal lumen).
Class and exam questions
What determines the choice of surgical method for a pararectal fistula?
Surgical tactics are determined by how exactly the fistulous tract and its openings (external and internal) are located relative to the anal sphincter.
Why is methylene blue injected into the fistula before surgery?
The dye is necessary for contrasting the walls. This allows the surgeon to visually track the entire fistulous tract and leave no affected tissue behind.
What is the essence of the Gabriel operation?
This intervention consists of the complete surgical excision of the pararectal fistula.
What is the main complication that must be prevented during the surgery?
The surgeon's most important task is not to damage the sphincter fibers in order to fully preserve its function.
What else to study on this topic
- Technique of the Gabriel procedure
- Features of the seton method application
- Stages of the Blinichev operation (lumen separation)
- Methodology of performing fistulography
- Defect plasty using the mucosal advancement method
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