Anal Fistula Closure – Procedures and Treatment

What Is Anal Fistula Closure?

Anal fistula closure describes a range of surgical and minimally invasive procedures designed to permanently seal an anal fistula. An anal fistula is an abnormal tunnel that typically forms between the inside of the anal canal and the skin surrounding the anus. It most commonly develops as a complication of an anal abscess that has not fully healed. Without treatment, an anal fistula can cause persistent discomfort, recurrent infections, and a significantly reduced quality of life.

Causes and Development of Anal Fistulas

The majority of anal fistulas originate from an infection of the small glands located inside the anus (cryptoglandular glands). When such an infection develops into an abscess and drains spontaneously or is surgically drained, it may leave behind a persistent channel. Less commonly, anal fistulas may be associated with:

• Crohn's disease (a chronic inflammatory bowel condition)
• Tuberculosis or other specific infections
• Previous surgery in the rectal or anal region
• Radiation damage following radiotherapy
• Carcinomas of the anal region

Symptoms of an Anal Fistula

Common signs and symptoms that may indicate an anal fistula include:

• Persistent or intermittent discharge of pus or blood from a small opening near the anus
• Pain, burning, or a feeling of pressure when sitting or during bowel movements
• Recurrent swelling or abscess formation in the perianal area
• Itching and skin irritation around the anus
• Occasional fever when active infection is present

Diagnosis

The diagnosis of an anal fistula is typically established through:

• Clinical examination: Visual inspection and gentle palpation of the perianal area to identify the external opening and trace the fistula tract.
• Proctoscopy: Examination of the anal canal using a rigid or flexible instrument to locate the internal opening.
• Endoanal ultrasound: An ultrasound probe inserted into the anal canal to map the exact course of the fistula tract in relation to the sphincter muscles.
• Pelvic MRI: Magnetic resonance imaging is the gold standard for complex or deep fistulas, providing detailed information on the anatomy and sphincter involvement.

Treatment Procedures for Anal Fistula Closure

The choice of procedure depends on the fistula's anatomy, its relationship to the sphincter muscles, and any underlying conditions. The primary goal is permanent closure of the fistula while preserving fecal continence (the ability to control bowel movements).

Fistulotomy

Fistulotomy involves surgically cutting open the entire fistula tract and allowing it to heal from the inside out. It is highly effective for low, superficial fistulas that involve little or no sphincter muscle and is considered the standard treatment for these cases.

Seton Drainage

A seton is a thread or thin plastic loop passed through the fistula tract. It may be used to drain secretions and prevent abscess formation (loose seton) or gradually tightened over time to slowly cut through the sphincter (cutting seton). It is also used as a staged approach to prepare for a definitive closure procedure.

Advancement Flap

The mucosal or rectal advancement flap technique covers the internal fistula opening with a flap of tissue taken from the rectal wall. It protects the sphincter muscle and is well suited for high or complex fistulas where sphincter preservation is critical.

LIFT Procedure (Ligation of Intersphincteric Fistula Tract)

The LIFT procedure involves identifying the fistula tract in the intersphincteric plane (the space between the internal and external sphincter muscles), ligating it, and dividing the tract. It offers a favorable balance between healing rates and continence preservation.

Anal Fistula Plug

A bioprosthetic plug, typically made from porcine small intestinal submucosa, is inserted into the fistula tract to serve as a scaffold for new tissue ingrowth. The approach is sphincter-sparing and minimally invasive, though reported success rates vary.

Fibrin Glue

Fibrin glue is a biological adhesive based on fibrinogen that is injected into the fistula tract to seal it. The procedure carries minimal risk and can be repeated, but long-term success rates are generally lower than those of surgical procedures.

VAAFT (Video-Assisted Anal Fistula Treatment)

VAAFT is a minimally invasive technique in which a small endoscope (fistuloscope) is inserted into the fistula tract. Under direct visualization, secondary tracts are identified and the fistula tissue is treated or sealed from within.

Stem Cell Therapy

For patients with Crohn's disease and complex perianal fistulas, local injection of mesenchymal stem cells (e.g., darvadstrocel/Alofisel) has shown promising results in clinical trials and is approved in the European Union for this specific indication.

Recovery and Healing

Consistent aftercare following anal fistula closure is essential for a successful outcome. This includes regular wound checks, careful anal hygiene, and sitz baths as recommended. The healing period varies by procedure and fistula complexity, ranging from a few weeks to several months. Recurrence is possible and may require repeat treatment.

Risks and Complications

Potential risks of anal fistula closure procedures include:

• Wound infection or abscess formation
• Postoperative bleeding
• Fistula recurrence
• Impairment of fecal continence, particularly with procedures involving sphincter muscle
• Delayed wound healing

References

1. Ommer A. et al. - S3-Leitlinie Kryptoglanduläre Analfisteln. Deutsche Gesellschaft für Koloproktologie (DGK), AWMF Register Nr. 081-003, 2023.
2. Garg P. - A systematic review of the LIFT procedure for fistula-in-ano. Colorectal Disease, 2017.
3. Panes J. et al. - Expanded allogeneic adipose-derived mesenchymal stem cells for complex perianal fistulas in Crohn's disease. Lancet, 2016.