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.

Neonates with TEF or esophageal atresia are unable to feed properly. Once diagnosed, prompt surgery is required to allow the food intake. Some children do experience problems following TEF surgery; they can develop dysphagia and thoracic problems. Children with TEF can also be born with other abnormalities, most commonly those described in VACTERL association - a group of anomalies which often occur together, including heart, kidney and limb deformities. 6% of babies with TEF also have a laryngeal cleft.

Rectovestibular fistula is the most common defect of the rectum and anal canal in females.

Birth injuries that result in the formation of fistulas and urinary and fecal incontinence have been found to be strongly associated with economic and cultural factors. Teenagers and women who sustain injuries that develop into ureterovaginal fistulas during childbirth suffer significant social stigma. Ureterovaginal fistulas related to prolonged, obstructed labor are rare in developed nations but are more common in countries where access to emergent obstetrical care is limited.

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.

Various types of fistulas include:

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

Many causes exist including:

- diverticulitis : most common ~ 60%

- colorectal cancer (CRC) : ~ 20%

- Crohn's disease : ~ 10%

- radiotherapy

- appendicitis

- trauma

In people with renal failure, requiring dialysis, a cimino fistula is often deliberately created in the arm by means of a short day surgery in order to permit easier withdrawal of blood for hemodialysis.

As a radical treatment for portal hypertension, surgical creation of a portacaval fistula produces an anastomosis between the hepatic portal vein and the inferior vena cava across the omental foramen (of Winslow). This spares the portal venous system from high pressure which can cause esophageal varices, caput medusae, and hemorrhoids.

If fecal matter passes through the fistula into the bladder, the existence of the fistula may be revealed by pneumaturia or fecaluria.

It is surgically corrected, with resection of any fistula and anastomosis of any discontinuous segments.

Depending on their relationship with the internal and external sphincter muscles, fistulae are classified into five types:

- Extrasphincteric fistulae begin at the rectum or sigmoid colon and proceed downward, through the levator ani muscle and open into the skin surrounding the anus. Note that this type does not arise from the dentate line (where the anal glands are located). Causes of this type could be from a rectal, pelvic or supralevator origin, usually secondary to Crohn's disease or an inflammatory process such as appendiceal or diverticular abscesses.

- Suprasphincteric fistulae begin between the internal and external sphincter muscles, extend above and cross the puborectalis muscle, proceed downward between the puborectalis and levator ani muscles, and open an inch or more away from the anus.

- Transphincteric fistulae begin between the internal and external sphincter muscles or behind the anus, cross the external sphincter muscle and open an inch or more away from the anus. These may take a 'U' shape and form multiple external openings. This is sometimes termed a 'horseshoe fistula.'

- Intersphincteric fistulae begin between the internal and external sphincter muscles, pass through the internal sphincter muscle, and open very close to the anus.

- Submucosal fistulae pass superficially beneath the submucosa and do not cross either sphincter muscle.

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.

One reason that poverty produces such high rates of fistula cases is the malnutrition that exists in such areas. Lack of money and access to proper nutrition, as well as vulnerability to diseases that exist in impoverished areas because of limited basic health care and disease prevention methods, cause inhabitants of these regions to experience stunted growth. Sub-Saharan Africa is one such environment where the shortest women have on average lighter babies and more difficulties during birth when compared with full-grown women. This stunted growth causes expectant mothers to have skeletons unequipped for proper birth, such as an underdeveloped pelvis. This weak and underdeveloped bone structure increases the chances that the baby will get stuck in the pelvis during birth, cutting off circulation and leading to tissue necrosis. Because of the correlation between malnutrition, stunted growth, and birthing difficulties, maternal height can at times be used as a measure for expected labor difficulties.

Poverty is the number one indirect cause of obstetric fistulae around the world. As obstructed labor and obstetric fistulae account for 8% of maternal deaths worldwide and “a 60-fold difference in gross national product per person shows up as a 120-fold difference in maternal mortality ratio,” it is clear that impoverished countries produce higher maternal mortality rates and thus higher obstetric fistula rates. Furthermore, impoverished countries not only have low incomes, but also lack adequate infrastructure, trained and educated professionals, resources, and a centralized government that exist in developed nations to effectively eradicate obstetric fistulae.

According to UNFPA, “Generally accepted estimates suggest that 2-3.5 million women live with obstetric fistulae in the developing world, and between 50,000 and 100,000 new cases develop each year. All but eliminated from the developed world, obstetric fistula continues to affect the poorest of the poor: women and girls living in some of the most resource-starved remote regions in the world.”

It can occur as a complication following biliary trauma (such as cholelithiasis), as an iatrogenic effect or as a result of a penetrating injury.

Imperforate anus has an estimated incidence of 1 in 5000 births. It affects boys and girls with similar frequency. However, imperforate anus will present as the low version 90% of the time in females and 50% of the time in males.

Imperforate anus is an occasional complication of sacrococcygeal teratoma.

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.

It is often caused by childbirth (in which case it is known as an obstetric fistula), when a prolonged labor presses the unborn child tightly against the pelvis, cutting off blood flow to the vesicovaginal wall. The affected tissue may necrotize (die), leaving a hole.

Vaginal fistulas can also result from particularly violent cases of rape, especially those involving multiple rapists and/or foreign objects. Some health centers in countries such as the Democratic Republic of Congo have begun to specialize in the surgical repair of vaginal fistulas.

It can also be associated with hysterectomy, cancer operations, radiation therapy and cone biopsy.

Anorectal anomalies are medical problems affecting the structure of the anus and rectum. A person with an anorectal problem would have some sort of deformative feature of the anus or rectum, collectively known as an anorectal malformation.

Examples of anorectal anomalies include:

- Anal stenosis

- Imperforate anus

- Proctitis

- Anal bleeding

- Anal fistula

- Anal cancer

- Anal itching

- Hemorrhoid (piles)

Vesicovaginal fistulae are typically repaired either transvaginally or laparoscopically, although patients who have had multiple transvaginal procedures sometimes attempt a final repair through a large abdominal incision, or laparotomy.

The laparoscopic (minimally invasive) approach to VVF repair has become more prevalent due to its greater visualization, higher success rate, and lower rate of complications.

Low-output fistula: < 200 mL/day

Moderate-output fistula: 200-500 mL/day

High-output fistula: > 500 mL/day

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.

With a high lesion, many children have problems controlling bowel function and most also become constipated. With a low lesion, children generally have good bowel control, but they may still become constipated.

For children who have a poor outcome for continence and constipation from the initial surgery, further surgery to better establish the angle between the anus and the rectum may improve continence and, for those with a large rectum, surgery to remove that dilated segment may significantly improve the bowel control for the patient. An antegrade enema mechanism can be established by joining the appendix to the skin (Malone stoma); however, establishing more normal anatomy is the priority.

The causes of diverticulitis are poorly understood, with approximately 40 percent due to genes and 60 percent due to environmental factors. Conditions that increase the risk of developing diverticulitis include arterial hypertension and immunosuppression. Obesity is another risk factor.

The mnemonic FRIENDS can be used to memorize characteristics which impede the closure of ECF.

F Foreign body

R Radiation

I Infection or Inflammatory bowel disease

E Epithelialization

N Neoplasm

D Distal obstruction

S Short tract (<2 cm)