A perianal fistula is an abnormal, hollow tunnel that develops beneath the skin near the anus, connecting the inside of the anal canal to the outside skin. People experiencing the discomfort and persistent drainage often wonder if the body can naturally close this tunnel. While the body possesses remarkable healing capabilities, the anatomical location and nature of this tract create significant barriers to spontaneous resolution. Understanding the structural challenges of the fistula explains why medical intervention is nearly always necessary to achieve a definitive cure.
What Exactly Is a Perianal Fistula?
A perianal fistula is a small passageway connecting a point inside the anal canal to an opening on the skin outside the anus. The primary origin of most fistulas is an infection in one of the tiny glands lining the anal canal. These glands can become blocked, allowing bacteria to multiply and form a painful collection of pus, known as an anorectal abscess.
The fistula is the chronic result of this acute infection. Once the abscess ruptures or is drained, a persistent tunnel remains, linking the original infected gland (the internal opening) to the site where the pus drained (the external opening). This tract can pass through some or all of the anal sphincter muscles, which are the ring-like muscles that control bowel movements. The path and depth of this tract determine its classification and the complexity of its treatment.
Why Spontaneous Healing Is Highly Unlikely
The likelihood of a perianal fistula healing without medical treatment is extremely low; most require surgical intervention. The constant presence of bacteria and contaminants from the intestinal tract creates an environment hostile to clean wound closure. Each time stool passes, the internal opening is exposed to fresh contamination, which continuously fuels the inflammatory process.
The fistula tract often becomes lined with epithelial cells or granulation tissue, a process called epithelialization. This lining creates a protective skin-like barrier within the tunnel, preventing the raw tissue surfaces from sticking together and healing shut. The body essentially attempts to turn the abnormal tunnel into a stable, permanent channel.
The constant movement and pressure from the surrounding anal sphincter muscles also mechanically prevent the tract from remaining closed long enough to heal. Even if the external opening on the skin appears to close, the internal opening remains, and the tunnel quickly fills with fluid, leading to a recurrence of the abscess. For these structural and mechanical reasons, spontaneous healing is considered an exception.
Risks Associated with Delaying Treatment
Attempting to wait for a perianal fistula to heal on its own can lead to significantly worse outcomes. The most common risk is the recurrence of infection, resulting in painful, recurring abscesses that require repeated drainage. Each new abscess can lead to a more intricate and difficult-to-treat fistula tract.
Delay allows the existing fistula to progress, potentially branching out into multiple side channels or extending deeper into surrounding tissue. This transformation from a simple, straight tract to a complex one makes future surgical repair considerably more challenging. The increased complexity raises the risk of damaging the anal sphincter during surgery, which can lead to problems with bowel control, or incontinence.
Over time, the persistent inflammation can cause damage to the sphincter muscles or lead to chronic scarring that narrows the anal canal, a condition called anal stricture. An untreated, long-standing infection also carries the risk of spreading beyond the local area, potentially leading to a systemic infection like sepsis.
Overview of Necessary Medical and Surgical Management
Because self-healing is unlikely, definitive treatment for a perianal fistula requires a medical or surgical approach. The first step involves careful assessment by a specialist, such as a colorectal surgeon, to determine the fistula’s path and its relationship to the anal sphincter muscles. Fistulas are generally classified as either simple (involving little or no sphincter muscle) or complex (involving a significant portion of the muscle or associated with underlying conditions).
For simple fistulas, the most common and successful treatment is a procedure called a fistulotomy. This involves opening the entire tract from the internal to the external opening, laying it open to allow it to heal from the bottom up. This method is highly effective and carries a low risk of damaging the sphincter muscles.
For complex fistulas, the primary goal is to eliminate the infection without compromising the patient’s ability to control their bowels. A temporary measure often used is the placement of a seton, a surgical thread or drain looped through the tract. The seton keeps the tract open, allowing for continuous drainage of infected material and controlling the infection before a definitive repair can be performed. More advanced, sphincter-sparing techniques are also employed, such as the Ligation of the Intersphincteric Fistula Tract (LIFT) procedure or an advancement flap.