Fistulas can develop in various parts of the body. The following list is sorted by the International Statistical Classification of Diseases and Related Health Problems.

Various types of fistulas include:

Although most fistulas are in forms of a tube, some can also have multiple branches.

Anal fistulae can present with the following symptoms:

- skin maceration

- pus, serous fluid and/or (rarely) feces discharge — can be bloody or purulent

- pruritus ani — itching

- depending on presence and severity of infection:

Anal fistula (plural fistulae), or fistula-in-ano, is a chronic abnormal communication between the epithelialised surface of the anal canal and (usually) the perianal skin. An anal fistula can be described as a narrow tunnel with its internal opening in the anal canal and its external opening in the skin near the anus. Anal fistulae commonly occur in people with a history of anal abscesses. They can form when anal abscesses do not heal properly.

Anal fistulae originate from the anal glands, which are located between the internal and external anal sphincter and drain into the anal canal. If the outlet of these glands becomes blocked, an abscess can form which can eventually extend to the skin surface. The tract formed by this process is a fistula.

Abscesses can recur if the fistula seals over, allowing the accumulation of pus. It can then extend to the surface again - repeating the process.

Anal fistulae "per se" do not generally harm, but can be very painful, and can be irritating because of the drainage of pus (it is also possible for formed stools to be passed through the fistula). Additionally, recurrent abscesses may lead to significant short term morbidity from pain and, importantly, create a starting point for systemic infection.

Treatment, in the form of surgery, is considered essential to allow drainage and prevent infection. Repair of the fistula itself is considered an elective procedure which many patients opt for due to the discomfort and inconvenience associated with an actively draining fistula.

Thyroglossal duct cysts most often present with a palpable asymptomatic midline neck mass above the level of the hyoid bone. The mass on the neck moves during swallowing or on protrusion of the tongue because of its attachment to the tongue via the tract of thyroid descent. Some patients will have neck or throat pain, or dysphagia.

The persistent duct or sinus can promote oral secretions, which may cause cysts to become infected. Up to half of thyroglossal cysts are not diagnosed until adult life. The tract can lie dormant for years or even decades, until some kind of stimulus leads to cystic dilation. Infection can sometimes cause the transient appearance of a mass or enlargement of the cyst, at times with periodic recurrences. Spontaneous drainage may also occur. Differential diagnosis are ectopic thyroid, enlarged lymph nodes, dermoid cysts and goiter.

Thyroglossal cyst usually presents as a midline neck lump (in the region of the hyoid bone) that is usually painless, smooth and cystic, though if infected, pain can occur. There may be difficulty breathing, dysphagia (difficulty swallowing), or dyspepsia (discomfort in the upper abdomen), especially if the cyst becomes large.

The most common location for a thyroglossal cyst is midline or slightly off midline, between the isthmus of the thyroid and the hyoid bone or just above the hyoid bone. A thyroglossal cyst can develop anywhere along a thyroglossal duct, though cysts within the tongue or in the floor of the mouth are rare.A thyroglossal cyst will move upwards with protrusion of the tongue.Thyroglossal cysts are associated with an increased incidence of ectopic thyroid tissue. Occasionally, a lingual thyroid can be seen as a flattened strawberry-like lump at the base of the tongue.

An infected thyroglossal duct cyst can occur when it is left untreated for a certain amount of time or simply when a thyroglossal duct cyst hasn't been suspected. The degree of infection can be examined as major rim enhancement has occurred, located inferior to the hyoid bone. Soft tissue swelling occurs, along with airway obstruction and trouble swallowing, due to the rapid enlargement of the cyst.

With infections, there can be rare cases where an expression of fluid is projected into the pharynx causing other problems within the neck.

A rectovaginal fistula is a medical condition where there is a fistula or abnormal connection between the rectum and the vagina.

Rectovaginal fistula may be extremely debilitating. If the opening between the rectum and vagina is wide it will allow both flatulence and feces to escape through the vagina, leading to fecal incontinence. There is an association with recurrent urinary and vaginal infections. The fistula may also connect the rectum and urethra, which is called recto-urethral fistula. Either conditions can lead to labial fusion. This type of fistula can cause pediatricians to misdiagnose imperforate anus. The severity of the symptoms will depend on the size of fistula. Most often, it appears after about one week or so after delivery.

A biliary fistula is a type of fistula in which bile flows along an abnormal connection from the bile ducts into nearby hollow structure. Types of biliary fistula include:

- bilioenteric fistula: abnormal connection to small bowel, usually duodenum.

- thoracobiliary fistula: abnormal connection to pleural space or bronchus (rare).

These may be contrasted to a bile leak, in which bile escapes the bile ducts through a perforation or faulty surgical anastomosis into the abdominal cavity. Damage to a bile duct may result in a leak, which may eventually become a biliary fistula.

A biliary fistula often occurs in be suspected in a person who has recently undergone a surgical procedure, Pain may occur if the leaked bile is also infected, which can subsequently lead to biliary peritonitis.

Extensive ascites may accumulate, especially in the setting of sterile bile leakage, which is often asymptomatic in nature.

If a colostomy is not performed immediately after birth, patients with rectovestibular fistulae may present later in life with complications including severe constipation and megacolon (abnormal dilation of the colon), requiring colostomy or further surgery.

Rectovaginal fistulas are often the result of trauma during childbirth (in which case it is known as obstetric fistula) where improper medical interventions are used, such as episiotomy with forceps/vacuum extraction or in situations where there is inadequate health care, such as in some developing countries. Rectovaginal fistula is said to be known as the leading cause in maternal death in developing countries. Risk factors include prolonged labour, difficult instrumental delivery and paramedian episiotomy. Rates in Eritrea are estimated as high as 350 per 100,000 vaginal births. Fistulas can also develop as a result of physical trauma to either the vagina or anus, including from rape. Women with rectovaginal fistulae are often stigmatized in developing countries, and become outcasts.

Rectovaginal fistula can also be a symptom of various diseases, including infection by lymphogranuloma venereum, or the unintended result of surgery, such as episiotomy or sexual reassignment surgery. They may present as a complication of vaginal surgery, including vaginal hysterectomy. They are a recognized presentation of rectal carcinoma or rarely diverticular disease of the bowel or Crohn's disease. They are seen rarely after radiotherapy treatment for cervical cancer.

Diagnosis is typically via a CT angiography, esophagogastroduodenoscopy, or arteriography. It is part of the differential diagnosis of gastrointestinal bleeding.

The most common signs/symptoms of DAVFs are:

1. Pulsatile tinnitus

2. Occipital bruit

3. Headache

4. Visual impairment

5. Papilledema

Pulsatile tinnitus is the most common symptom in patients, and it is associated with transverse-sigmoid sinus DAVFs. Carotid-cavernous DAVFs, on the other hand, are more closely associated with pulsatile exophthalmos. DAVFs may also be asymptomatic (e.g. cavernous sinus DAVFs).

A ureterovaginal fistula is an abnormal passageway existing between the ureter and the vagina. It presents as urinary incontinence. Its impact on women is to reduce the "quality of life dramatically."

Surgically created AV fistulas work effectively because they:

- Have high volume flow rates (as blood takes the path of least resistance; it prefers the (low resistance) AV fistula over traversing (high resistance) capillary beds).

- Use native blood vessels, which, when compared to synthetic grafts, are less likely to develop stenoses and fail.

Symptoms of obstetric fistula include:

- Flatulence, urinary or fecal incontinence, which may be continual or only happen at night

- Foul-smelling vaginal discharge

- Repeated vaginal or urinary tract infections

- Irritation or pain in the vagina or surrounding areas

- Pain during sexual activity

Other effects of obstetric fistulae include stillborn babies due to prolonged labor, which happens 85% to 100% of the time, severe ulcerations of the vaginal tract, "foot drop", which is the paralysis of the lower limbs caused by nerve damage, making it impossible for women to walk, infection of the fistula forming an abscess, and up to two-thirds of the women become amenorrhoeic.

Obstetric fistulae have far-reaching physical, social, economic, and psychological consequences for the women affected.

According to UNFPA, “Due to the prolonged obstructed labour, the baby almost inevitably dies, and the woman is left with chronic incontinence. Unable to control the flow of urine or faeces, or both, she may be abandoned by her husband and family and ostracized by her community. Without treatment, her prospects for work and family life are virtually non-existent.”

A rectovestibular fistula, also referred to simply as a vestibular fistula, is an anorectal congenital disorder where an abnormal connection (fistula) exists between the rectum and the vulval vestibule of the female genitalia.

If the fistula occurs within the hymen, it is known as a rectovaginal fistula, a much rarer condition.

A urerovaginal fistula is a result of trauma, infection, pelvic surgery, radiation treatment and therapy, malignancy, or inflammatory bowel disease. Symptoms can be troubling for women especially since some clinicians delay treatment until inflammation is reduced and stronger tissue has formed. The fistula may develop as a maternal birth injury from a long and protracted labor, long dilation time and expulsion period. Difficult deliveries can create pressure necrosis in the tissue that is being pushed between the head of the infant and the softer tissues of the vagina, ureters, and bladder.

Radiographic imaging can assist clinicians in identifying the abnormality. A Ureterovaginal fistula is always indicative of an obstructed kidney necessitating emergency intervention followed later by an elective surgical repair of the fistula.

A Cimino fistula, also Cimino-Brescia fistula, surgically created arteriovenous fistula and (less precisely) arteriovenous fistula (often abbreviated AV fistula or AVF), is a type of vascular access for hemodialysis. It is typically a surgically created connection between an artery and a vein in the arm, although there have been acquired arteriovenous fistulas which do not in fact demonstrate connection to an artery.

A fistula involving the bladder can have one of many specific names, describing the specific location of its outlet:

- Bladder and intestine: "vesicoenteric", "enterovesical", or "vesicointestinal"

- Bladder and colon: "vesicocolic" or "colovesical"

- Bladder and rectum: "vesicorectal" or "rectovesical"

An aortoenteric fistula is a connection between the aorta and the intestines, stomach, or esophageus. There can be significant blood loss into the intestines resulting in bloody stool and death. It is usually secondary to an abdominal aortic aneurysm repair.

Fistulae between the trachea and esophagus in the newborn can be of diverse morphology and anatomical location; however, various pediatric surgical publications have attempted a classification system based on the below specified types.

Not all types include both esophageal agenesis and tracheoesophageal fistula, but the most common types do.

The letter codes are usually associated with the system used by Gross, while number codes are usually associated with Vogt.

An additional type, "blind upper segment only" has been described, but this type is not usually included in most classifications.

Low-output fistula: < 500 mL/day

High-output fistula: > 500 mL/day

Many lymphoceles are asymptomatic. Larger lymphoceles may cause symptoms related to compression of adjacent structures leading to lower abdominal pain, abdominal fullness, constipation, urinary frequency, and edema of the genitals and/or legs. Serious sequelae could develop and include infection of the lymphocele, obstruction and infection of the urinary tract, intestinal obstruction, venous thrombosis, pulmonary embolism, chylous ascites and lymphatic fistula formation.

On clinical examination the skin may be reddened and swollen and a mass felt. Ultrasonography or CT scan will help to establish a diagnosis.

Other fluid collections to be considered in the differential diagnosis are urinoma, seroma, hematoma, as well as collections of pus. Also, when lower limb edema is present, venous thrombosis needs to be considered.

A preauricular sinus (also known as a congenital auricular fistula, a congenital preauricular fistula, a Geswein hole, an ear pit, or a preauricular cyst) is a common congenital malformation characterized by a nodule, dent or dimple located anywhere adjacent to the external ear. Frequency of preauricular sinus differs depending the population: 0.1-0.9% in the US, 0.9% in the UK, and 4-10% in Asia and parts of Africa. Comparative frequency is known to be higher in Africans and Asians than in Caucasians.

Preauricular sinuses are inherited features, and most often appear unilaterally. They are present bilaterally in 25-50% of cases.