About Anal Fistula

An anal fistula is an abnormal tunnel that forms between the inner lining of the anal canal and the outer skin near the anus. It usually develops after an infection in an anal gland leads to an abscess that fails to heal properly. As the infection drains, it creates a tract that may persist, causing ongoing discharge, pain, or swelling.

While not life-threatening, an untreated fistula can severely impact quality of life and lead to repeated infections. Fistulas can be simple or complex and are classified based on their path relative to the anal sphincter muscles. Prompt diagnosis and appropriate treatment, especially in high-risk or recurrent cases, are essential to avoid complications.

Anal Fistula Signs and Symptoms

• Persistent pus or fluid discharge near the anus
• Pain that worsens during sitting or bowel movements
• Swelling, redness, or a boil-like lump near the anal area
• Skin irritation or itching around the opening
• Fever or fatigue in case of active infection
• A small hole or external opening near the anus
• Recurrence of abscess in the same spot

Anal Fistula Causes

Previous Anal Abscess

• Mechanism: An untreated or inadequately healed abscess can leave a tract.
• Effect: Chronic drainage through the skin forms a fistula.

Crohn’s Disease and Other Inflammatory Conditions

• Mechanism: Chronic inflammation weakens the anal tissue.
• Effect: Creates an environment prone to tunnel formation.

Tuberculosis or STIs

• Mechanism: Infectious agents damage anal and rectal tissues.
• Effect: May result in complex or multiple fistulous tracts.

Post-Surgical Complications

• Mechanism: Healing issues after anorectal surgery.
• Effect: Can lead to abnormal passageways forming.

Radiation or Trauma

• Mechanism: Tissue damage and poor healing response.
• Effect: May cause fistula development in rare cases.

Anal Fistula Risk Factors

• History of anal abscess
• Conditions like Crohn’s disease or ulcerative colitis
• Immune-suppressing illnesses (e.g., HIV)
• Anal trauma or recent surgeries
• Chronic diarrhea or constipation
• Tuberculosis or sexually transmitted infections
• Repeated anorectal infections

Anal Fistula Complications

• Recurrent Abscesses: May occur if the tract remains open
• Chronic Drainage: Continuous oozing of pus or fluid
• Fistula Tract Branching: Multiple paths can complicate treatment
• Anal Incontinence: If surrounding muscles are affected
• Sepsis: Rare but serious complication if infection spreads
• Scarring and Tissue Damage: May occur with delayed care

Anal Fistula Diagnosis

Clinical Assessment : A doctor will examine the anal area for signs of external openings, discharge, or redness. Gentle pressure may reveal pus drainage.

Digital Rectal Examination (DRE) : Used to assess the internal opening or path of the fistula and check for tenderness or induration.

Imaging Studies

• MRI Fistulogram: Best for mapping complex or branching tracts
• Endoanal Ultrasound: Helps define tract location and involvement of anal muscles
• CT Scan or Fistulography: Occasionally used for complicated or recurrent cases

Anal Fistula Treatment Options

Anal fistulas rarely heal on their own and often require surgical treatment. The type of surgery depends on the complexity and location of the fistula.

Non-Surgical Measures (for selected cases)

• Antibiotics: To manage active infection
• Seton Placement (Temporary Thread): Maintains drainage and reduces inflammation before definitive surgery

Anal Fistula Surgical Management

• Fistulotomy : The fistula tract is laid open and allowed to heal from the base. Effective for simple, superficial fistulas.
• LIFT Procedure (Ligation of Intersphincteric Fistula Tract) : Used for trans-sphincteric fistulas. The internal opening is sealed, preserving the sphincter muscle.
• VAAFT (Video-Assisted Anal Fistula Treatment) : A minimally invasive method using an endoscopic camera to locate and close the tract.
• Advancement Flap Surgery : For complex or high fistulas. Healthy tissue is moved to cover the internal opening after excising the fistula.
• Fibrin Glue or Collagen Plug : Less invasive options in select cases; used to seal the tract without cutting tissue.