Fistula

A fistula is an abnormal connection between two parts of the body that, under normal conditions, are not connected to each other. It is a channel with fibrous walls that links an organ to another epithelial structure, such as the skin or the digestive, tracheal, gynecological, or urological mucosa, for example.

In most cases, fistulas form due to injury or surgical intervention, although they may also result from infection or inflammation. Depending on their characteristics, they can be:

• Blind fistulas: connect two structures but are open at only one end. They do not connect to the exterior.
• Complete fistulas: have two openings, one internal and one external to the body.
• Horseshoe fistulas: occur in the anus or anorectal region. They connect the anus to the external skin, surrounding the rectum.
• Incomplete fistulas: have a single opening and do not fully connect two structures because the tract ends before traversing the tissue.

Fistulas can appear in very different parts of the body and connect various structures. The most relevant include:

• Perianal fistula: the most common type. It is a connection between the anal canal or rectum and the skin surrounding the anus.
• Arteriovenous fistula: an artery connects with a vein.
  • Pulmonary arteriovenous fistula: connects two vessels located in the lungs, leading to impaired oxygenation.
  • Dural arteriovenous fistula: connects two blood vessels in the brain.
  • Arteriovenous fistula of the extremities: connects an artery and a vein in the arms or legs.
  • Carotid-cavernous fistula: a connection between the carotid artery and the cavernous sinus, a venous structure in the skull.
  • Dialysis fistula: surgically created in patients with kidney failure. It connects an artery and a vein, usually in the arm, to facilitate hemodialysis by providing durable and safe vascular access.
• Coccygeal fistula or pilonidal sinus: connects the skin of the intergluteal region (between the buttocks) with a cyst located in the coccyx or sacral bone, usually due to infection from an ingrown hair.
• Preauricular fistula: located in front of the ear, connecting the skin with deeper structures. In some cases, it may extend to the parotid gland. It is usually congenital.
• Tracheoesophageal fistula: a highly dangerous condition in which the trachea and esophagus are connected, allowing food to enter the airways. It typically occurs in newborns.
• Enteral fistula: abnormal connection between the gastrointestinal tract (stomach or intestines) and adjacent organs.
  • Enterovesical fistula: connects the intestine and the bladder. It is more common in women due to the anatomical position of the uterus between the bladder and intestines.
  • Colovesical fistula: the most common fistula in the digestive system. It connects the bladder with the colon.
  • Enterocutaneous fistula: connects the intestine to the skin, with an external opening.
  • Enteroenteric fistula: connects two different parts of the intestine.
  • Aortoenteric fistulas: very rare. They involve a connection between the aorta and the small intestine.
• Vaginal fistula: occurs between the vagina and a nearby organ:
  • Vesicovaginal fistula: abnormal connection between the bladder and the vagina.
  • Ureterovaginal fistula: connects the vagina with the ureters, which transport urine between the kidneys and bladder.
  • Urethrovaginal fistula: between the vagina and the urethra, the duct that carries urine outside the body.
  • Rectovaginal fistula: between the vagina and the rectum.
  • Colovaginal fistula: between the vagina and the colon.

The prognosis of a fistula is generally good if diagnosed early and treated appropriately, usually with surgical intervention. Recovery time varies depending on the location.

Symptoms

Symptoms of a fistula vary depending on the affected area:

• Perianal fistula:
  • Inflammation.
  • Lump in the anus or anal canal, which increases when sitting, moving, or during defecation.
  • Pus discharge.
  • Bloody stools.

• Arteriovenous fistula:
  • Pulmonary arteriovenous fistula:
    • Dyspnea (shortness of breath).
    • Cyanosis (bluish skin discoloration).
    • Hypoxemia (low blood oxygen levels).
    • Clubbing of fingers.
    • Hemoptysis or frequent nosebleeds.
    • Chest pain.
    • Fatigue.
  • Dural arteriovenous fistula:
    • Pulsatile tinnitus: rhythmic buzzing in the ear that coincides with the heartbeat.
    • Exophthalmos (protruding eyes).
    • Decreased visual acuity, double vision.
    • Persistent headache.
    • Seizures.
    • Weakness.
    • Speech difficulties.
    • Behavioral changes.
    • Memory problems.

• • Arteriovenous fistula in the extremities:
    • Dilated purple varicose veins.
    • Edema (swelling).
    • Local warmth.
    • Cramps.
    • Pain.
    • Abnormal pulse: palpable or audible bruit over the fistula.
  • Carotid-cavernous fistula:
    • Proptosis (prominent eyes).
    • Conjunctival edema: swelling of the membrane that covers the eye and lines the inner surface of the eyelid.
    • Dilated ocular vessels causing "red eye."
    • Diplopia (double vision).
    • Vision loss.
    • Increased intraocular pressure, potentially leading to glaucoma.
    • Head and eye pain.
    • Excessive tearing.
    • Cranial nerve palsy.
    • Orbital bruit (patient hears a pulsatile whistling sound).
• Coccygeal fistula:
  • Pain at the base of the spine, worsening when sitting.
  • Visible lump between the buttocks.
  • Pus or blood discharge.
  • Inflammation.
  • Local warmth and moisture.
• Preauricular fistula:
  • Small opening in front of the ear.
  • Redness.
  • Inflammation.
  • Purulent discharge.
  • Pain.
• Tracheoesophageal fistula:
  • Choking during feeding.
  • Vomiting after feeding.
  • Cough.
  • Respiratory distress.
  • Recurrent aspiration pneumonia.
  • Wheezing.
  • Cyanosis.
  • Excessive salivation.
  • Abdominal distension.
• Enteral fistula:
  • Enterovesical and colovesical fistulas:
    • Pneumaturia (air in urine, often audible).
    • Fecaluria (fecal matter in urine).
    • Recurrent urinary tract infections.
    • Lower abdominal pain.
    • Dysuria (burning sensation during urination).
    • Foul-smelling urine.
  • Enterocutaneous fistula:
    • Pus discharge.
    • Fecal or bile leakage externally.
    • Abdominal pain.
    • Skin irritation.
    • Fever.
    • Weight loss.
  • Enteroenteric fistula:
    • Abdominal pain.
    • Chronic diarrhea.
    • Weight loss.
    • Nausea and vomiting.
    • Infection, abscesses.
  • Aortoenteric fistula:
    • Gastrointestinal bleeding.
    • Pulsatile abdominal mass.
    • Constant abdominal pain.
    • Fever.
    • General malaise.
• Vaginal fistula:
  • Vesicovaginal, ureterovaginal, and urethrovaginal fistulas:
    • Urine leakage through the vagina.
    • Recurrent urinary tract infections resistant to treatment.
    • Irritation.
    • Vulvar dermatitis.
    • Perineal discomfort.
    • Foul genital odor.
    • Dyspareunia (pain during sexual intercourse).
  • Rectovaginal and colovaginal fistulas:
    • Passage of gas and fecal matter through the vagina.
    • Vaginal discharge with foul odor and purulent appearance.
    • Urinary and vaginal infections.
    • Perineal irritation.
    • Fecal or urinary incontinence.
    • Inflammation.
    • Pain.

Causes

Fistulas are classified into two types depending on their origin:

• Congenital fistulas: present at birth.
• Acquired fistulas: result from disease, trauma, or medical treatment.

The causes vary significantly depending on the type:

• Perianal fistula: usually results from obstruction of a gland that becomes inflamed and infected, forming a pus-filled abscess. When this abscess drains (spontaneously or surgically), a fistula may develop. It is common in patients with inflammatory bowel diseases (especially Crohn’s disease) or perianal abscesses. Less frequently, it may result from trauma, infection, cancer, or a foreign body.
• Arteriovenous fistula: caused by trauma, penetrating injuries, infections, congenital defects, or surgical procedures.
  • Pulmonary arteriovenous fistula: usually congenital. Rarely, caused by trauma or metastasis.
  • Dural arteriovenous fistula: due to cavernous sinus thrombosis, coagulation disorders, or head trauma.
  • Arteriovenous fistula in the extremities: due to congenital defects, trauma, or surgery (including dialysis fistulas).
  • Carotid-cavernous fistula: most commonly due to head trauma. Other causes include hypertension, aneurysms, atherosclerosis, or cavernous sinus thrombosis.
• Coccygeal fistula: caused by an ingrown hair that becomes trapped in the follicle. External communication is facilitated by excessive friction or prolonged sitting.
• Preauricular fistula: congenital developmental defect due to incomplete fusion of the auricular structures during embryogenesis.
• Tracheoesophageal fistula: most commonly a congenital malformation in newborns. It may also result from trauma, esophageal tumors, or complications of medical procedures such as tracheostomy or mechanical ventilation.
• Enteral fistula: mainly a postoperative complication, but may also be caused by infection, trauma, malignancy, or inflammatory bowel disease (diverticulitis, ulcerative colitis, Crohn’s disease). Aortoenteric fistulas may result from abdominal aortic aneurysm or postoperative infection after vascular reconstruction.
• Vaginal fistula: most commonly a complication after pelvic surgery, typically hysterectomy. It may also result from obstetric trauma (e.g., childbirth), pelvic radiotherapy, or inflammatory bowel disease.

Risk Factors

The risk of developing a fistula is higher in patients with the following conditions:

• Abscesses (pus accumulation due to infection).
• Inflammatory bowel diseases: Crohn’s disease, ulcerative colitis, diverticulitis.
• Trauma.
• Sexually transmitted infections.
• Diabetes.
• Hypertension.
• Obesity.
• Cancer.
• Complicated childbirth.
• Immunosuppression.
• Radiotherapy.
  
• Cardiac catheterization.
• Surgery.

Complications

Common complications of any fistula include:

• Infection.
• Abscesses with persistent drainage.
• Severe pain.
• Tendency to recurrence.
• Sepsis: life-threatening systemic bacterial infection.

In addition, specific complications include:

• Enteral and perianal fistulas:
  • Peritonitis (abdominal cavity infection).
  • Fecal incontinence.
  • Malnutrition.
  • Dehydration.
  • Skin complications: excoriation, severe dermatitis, and ulceration around the fistula opening.
• Arteriovenous fistulas:
  • Thrombosis (clot formation obstructing blood vessels).
  • Heart failure.
  • Aneurysms (vessel dilation).
  • Stenosis (vessel narrowing).
• Vaginal fistulas:
  • Recurrent pelvic infections.
  • Abscesses.
  • Narrowing of organs (vagina or rectum).
  • Chronic pain.
  • Psychological distress due to leakage of feces and gas through the vagina.
• Coccygeal fistula:
  • Disabling pain affecting walking, sitting, or driving, significantly impairing quality of life.
  • Chronic infection.
• Tracheoesophageal fistula:
  • Aspiration pneumonia.
  • Respiratory distress.
  • Gastroesophageal reflux.
  • Esophageal stenosis causing dysphagia (difficulty swallowing).
  • Malnutrition and weight loss.
  • Tracheomalacia (tracheal cartilage weakness).
  • Asphyxia.
• Preauricular fistula: abscesses and cysts.

Which doctor treats fistulas?

Fistulas are managed in the specialties of General and digestive system surgery, Urology, Gynecology and Obstetrics, Angiology and Vascular surgery, or Neurosurgery.