Rigi10™ Malleable Penile Prosthesis
Also Known As
Abnormal passage, pathological connection, sinus tract, abnormal tract, fistulous tract, epithelialized tract, pathological duct, abnormal communication
Definition
A fistula is an abnormal connection between two epithelized surfaces or body parts that normally do not connect.1 This pathological passage can form between any two hollow spaces including blood vessels, intestine, vagina, bladder, and skin.2 Fistulas are categorized in three different ways: anatomically, physiologically, and etiologically.2
Anatomically, fistulas are subdivided into two categories:
- Internal fistulas: Connections between two internal structures (e.g., enterocolic, ileosigmoid, aortoenteric)2
- External fistulas: Connections between an internal structure and external structure (e.g., enterocutaneous, enteroatmospheric, rectovaginal)2
When categorized physiologically, fistulas are differentiated based on fluid output:
- Low-output fistulas: Drain less than 200 ml of fluid per day2
- Medium-output fistulas: Drain between 200-500 ml of fluid per day2
- High-output fistulas: Drain greater than 500 ml of fluid per day2
Etiologically, fistulas are categorized based on their cause, with common categories including traumatic fistulas, surgical site fistulas, and fistulas associated with inflammatory conditions such as Crohn’s disease.2
Clinical Context
Fistulas can occur in many parts of the body and form between various structures.3 They most commonly result from infection, inflammation, trauma, or as a complication of surgery.1,2 The clinical presentation varies depending on the location and type of fistula.
Perianal/Anal Fistulas
A fistula-in-ano is a tract connecting the anal canal to the perianal skin.3 It requires surgical treatment in the majority of cases. Proper management increases a patient’s quality of life.3 Anal fistulas are commonly the result of an anorectal abscess, with 30% to 70% of patients with an anorectal abscess having a concurrent fistula-in-ano.1 Classification of anal fistulas is based on anatomy, specifically in relation to the sphincter complex:
- Intersphincteric (45%): The fistula penetrates through the internal sphincter but spares the external sphincter3
- Transphincteric (30%): The fistula passes through both the internal and external sphincters3
- Suprasphincteric (20%): The fistula penetrates through the internal sphincter and then extends superiorly in the plane between the sphincters to pass above the external sphincter before extending to the perineum3
- Extrasphincteric (5%): This rare fistula forms a connection from the rectum to the perineum that extends laterally to the internal and external sphincter3
Enterocutaneous Fistulas
These are abnormal connections between the gastrointestinal tract and the skin.2 They are categorized physiologically based on output volume, with management strategies varying accordingly. Patients are at high risk for electrolyte imbalances, sepsis, and malnutrition, making stabilization the first step in management.2
Other Types
- Arteriovenous fistulas (between an artery and vein)
- Biliary fistulas (from gallbladder surgery)
- Cervicovaginal fistulas
- Vesicovaginal fistulas (between bladder and vagina)
- Tracheoesophageal fistulas
- Aortoenteric fistulas
Diagnosis typically involves physical examination, imaging studies (MRI, endoanal ultrasound, fistulography, CT), and sometimes examination under anesthesia.3,5 MRI is considered the most sensitive (>90%) imaging modality for fistula evaluation.3
Treatment approaches vary based on fistula type, location, and underlying cause. Surgical management is the mainstay of treatment for most fistulas, particularly anal fistulas.1,3 Medical management may be considered in certain situations, especially for fistulas associated with inflammatory bowel disease.1 The primary goals of treatment are to manage infection, ensure functional preservation (such as fecal continence in anal fistulas), and improve quality of life.1,3