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Anal Fistula

General Surgery

Anal fistula refers to a condition where a channel forms outward between the rectum and the skin near the anus due to bacterial infection and the subsequent formation of pus inside the anal area.

The inner wall of the fistulous tract consists of fibrous tissue and granulation tissue, with the inner end connecting to the anus or rectum and the outer end connecting to the skin near the anus. It is a complication caused by anal abscesses. Depending on the location of the external opening and the course of the fistulous tract within the anal sphincter, it can be classified into two types: complex and simple.

Symptoms

The Anus area skin has an opening
The skin around the fistula opening becomes red and inflamed
Pus, blood, or faeces ooze from the fistula opening
Rectal and anal pain, especially when sitting or during bowel movements
Fever

Factors

Anal fistulas are typically caused by infections or inflammations in the anal or rectal region. Anal fistulas can occur at any age, but it more commonly occurs in middle-aged patients, and the proportion of male patients is higher than female patients.

The primary causes include:

Anal Abscess	One of the most common causes of anal fistulas is anal abscesses. Anal glands, located around the anus, are responsible for secreting mucus to facilitate smooth bowel movements. When these glands become infected or blocked, it can lead to anal abscesses, which may ultimately result in the formation of an anal fistula.
Inflammatory Bowel Diseases	Conditions such as Crohn's disease or ulcerative colitis can cause inflammation within the rectum, and this inflammation can spread to surrounding tissues, leading to the formation of an anal fistula.
Haemorrhoids	Haemorrhoids are swollen masses or lumps inside the anal canal. When haemorrhoids become infected or inflamed, they may lead to the development of an anal fistula.
Other Perianal Infections	Other infections, such as skin diseases, perianal infections, trauma, or cancer, can sometimes also result in the formation of an anal fistula.

Diagnosis and Treatments

Surgical specialists will examine the skin around the anus to check for symptoms such as redness, pus, bleeding, and more. Suppose a fistula is suspected to be complex or challenging to locate. In that case, doctors may consider using Magnetic Resonance Imaging (MRI) for more accurate and precise observation of the fistula tract between its internal and external openings, providing the most effective treatment for patients.

Anal fistulas do not heal on their own, are typically chronic, and tend to worsen over time. To effectively treat and cure an anal fistula, reduce the risk of recurrence, and avoid causing faecal incontinence, surgery is necessary.

The type of surgery performed depends on the location and complexity of the fistula tract. Still, the primary goal of surgery is to thoroughly remove the anal fistula, prevent a recurrence, and protect the sphincter muscles, as damage to the sphincter muscles can lead to faecal incontinence.

Simple Anal Fistulas

These can be treated with open surgery (fistulotomy or fistulectomy). In fistulotomy, the surgeon makes a small incision between both internal and external opening of the fistula tract, removing and draining all pus and infected tissue. Fistulectomy involves the complete removal of the entire fistula tract. The wound naturally heals, new tissue grows and fills the wound gap between 3-4 weeks of time.

Complex Anal Fistulas

If the fistula is deep, has multiple tracts or openings, it cannot be removed entirely, as doing so would cause too much damage to anal sphincter muscle, which may lead to faecal incontinence. Therefore, alternative surgical methods are necessary:

Seton Placement: A plastic thread (seton) is inserted into the fistula tract to aid in draining the pus as draining seton. The seton may be tightened, making the tract behind it smaller over time, allowing the body to heal the wound and self-repair the tissue gradually (cutting seton). While this method does slowly cut the anal sphincter muscle, it gives the body time to slow and continuously repair the tissue throughout the entire surgical process to avoid faecal incontinence.
Ligation of Intersphincteric Fistula Tract (LIFT): This surgical procedure disconnects the communication between the openings of the fistula tract without harming the anal sphincter muscles, with the aim of preventing bacteria from entering the fistula tract within the anus. As the operation avoid cutting the sphincter muscle, it causes minimal risk of faecal incontinence.
Advancement Flap: This involves taking mucosal tissue from the rectal wall inside before excising the fistula tract's internal opening. The area is then covered with a flap of skin. This treatment aims to close the inner opening, preventing bacteria from entering and allowing the external part to heal gradually.
Video-assisted Anal Fistula Therapy (VAAFT): The procedure is using a small endoscope to identify the fistula tract and opening, cauterize the tract and then closes the internal opening from inside the anal canal using stitches and staples.
Laser Therapy: Laser therapy involves inserting a laser probe into the external opening of the fistula tract to close the entire channel. The energy emitted by the laser gradually breaks down the abscess tissue, causing it to shrink into scar tissue.