A gastrojejunocolic fistula is a disorder of the human gastrointestinal tract. It may form between the transverse colon and the upper jejunum after a Billroth II surgical procedure. (The Billroth procedure attaches the jejunum to the remainder of the stomach). Fecal matter thereby passes improperly from the colon to the stomach, and causes halitosis.

Patients may present with diarrhea, weight loss and halitosis as a result of fecal matter passing through the fistula from the colon into the stomach.

Diverticulitis typically presents with left lower quadrant abdominal pain of sudden onset. There may also be fever, nausea, diarrhea or constipation, and blood in the stool.

In complicated diverticulitis, an inflamed diverticulum can rupture, allowing bacteria to subsequently infect externally from the colon. If the infection spreads to the lining of the abdominal cavity (the peritoneum), peritonitis results. Sometimes, inflamed diverticula can cause narrowing of the bowel, leading to an obstruction. In some cases, the affected part of the colon adheres to the bladder or other organs in the pelvic cavity, causing a , or creating an abnormal connection between an organ and adjacent structure or other organ (in the case of diverticulitis, the colon and an adjacent organ).

Related pathologies may include:

- Bowel obstruction

- Peritonitis

- Abscess

- Bleeding

- Strictures

Fecal vomiting, also called feculent vomiting and stercoraceous vomiting is a kind of vomiting wherein the material vomited is of fecal origin. It is a common symptom of gastrojejunocolic fistula and intestinal obstruction in the ileum. Fecal vomiting is often accompanied by an odor of feces on the breath and other gastrointestinal symptoms, including abdominal pain, abdominal distension, dehydration, and diarrhea. In severe cases of bowel obstruction or constipation (such as those related to Clozapine-treatment) fecal vomiting has been identified as a cause of death.

Fecal vomiting occurs when the bowel is obstructed for some reason, and intestinal contents cannot move normally. Peristaltic waves occur in an attempt to decompress the intestine, and the strong contractions of the intestinal muscles push the contents backwards through the pyloric sphincter into the stomach, where they are then vomited.

Fecal vomiting can also occur in cats.

Fecal vomiting does not include vomiting of the proximal small intestine contents, which commonly occurs during vomiting.

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

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"

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

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.

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.

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:

A pancreatic fistula is an abnormal communication between the pancreas and other organs due to leakage of pancreatic secretions from damaged pancreatic ducts. An "external" pancreatic fistula is one that communicates with the skin, and is also known as a pancreaticocutaneous fistula, whereas an internal pancreatic fistula communicates with other internal organs or spaces. Pancreatic fistulas can be caused by pancreatic disease, trauma, or surgery.

An external pancreatic fistula is an abnormal communication between the pancreas (actually pancreatic duct) and the exterior of the body via the abdominal wall.

Loss of bicarbonate-rich pancreatic fluid via a pancreatic fistula can result in a hyperchloraemic or normal anion gap metabolic acidosis. Loss of a small volume of fluid will not cause a problem but an acidosis is common if the volume of pancreatic fluid lost from the body is large.

Tracheoesophageal fistula is suggested in a newborn by copious salivation associated with choking, coughing, vomiting, and cyanosis coincident with the onset of feeding. Esophageal atresia and the subsequent inability to swallow typically cause polyhydramnios in utero. Rarely it may present in an adult.

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.

Surgical repair can sometimes result in complications, including:

- Stricture, due to gastric acid erosion of the shortened esophagus

- Leak of contents at the point of anastomosis

- Recurrence of fistula

- Gastro-esophageal reflux disease

- Dysphagia

- Asthma-like symptoms, such as persistent coughing/wheezing

- Recurrent chest infections

- Tracheomalacia

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.

Various types of fistulas include:

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

Mirizzi's syndrome is a rare complication in which a gallstone becomes impacted in the cystic duct or neck of the gallbladder causing compression of the common bile duct (CBD) or common hepatic duct, resulting in obstruction and jaundice. The obstructive jaundice can be caused by direct extrinsic compression by the stone or from fibrosis caused by chronic cholecystitis (inflammation). A cholecystocholedochal fistula can occur.

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.

An enterocutaneous fistula (ECF) is an abnormal communication between the small or large bowel and the skin that allows the contents of the stomach or intestines to leak through an opening in the skin.

The diagnosis of a rectovestibular fistula can be made in female newborns if the vulva is stained with meconium (the earliest form of stool in an infant). The opening of the anus may be difficult to see due to its small size and position, but it may be visible as a thickening of the median perineal raphe with an obvious anal dimple. Patients with rectovestibular fistulae are commonly misdiagnosed with rectovaginal fistulae.

Esophageal diseases can derive from congenital conditions, or they can be acquired later in life.

Many people experience a burning sensation in their chest occasionally, caused by stomach acids refluxing into the esophagus, normally called heartburn. Extended exposure to heartburn may erode the lining of the esophagus, leading potentially to Barrett's esophagus which is associated with an increased risk of adenocarcinoma most commonly found in the distal one-third of the esophagus.

Some people also experience a sensation known as globus esophagus, where it feels as if a ball is lodged in the lower part of the esophagus.

The following are additional diseases and conditions that affect the esophagus:

- Achalasia

- Acute esophageal necrosis

- Barrett's esophagus

- Boerhaave syndrome

- Caustic injury to the esophagus

- Chagas disease

- Diffuse esophageal spasm

- Esophageal atresia and Tracheoesophageal fistula

- Esophageal cancer

- Esophageal dysphagia

- Esophageal varices

- Esophageal web

- Esophagitis

- GERD

- Hiatus hernia

- Jackhammer esophagus (hypercontractile peristalsis)

- Killian–Jamieson diverticulum

- Mallory-Weiss syndrome

- Neurogenic dysphagia

- Nutcracker esophagus

- Schatzki's ring

- Zenker's Diverticulum

Mirizzi's syndrome has no consistent or unique clinical features that distinguish it from other more common forms of obstructive jaundice. Symptoms of recurrent cholangitis, jaundice, right upper quadrant pain, and elevated bilirubin and alkaline phosphatase may or may not be present. Acute presentations of the syndrome include symptoms consistent with cholecystitis.

Surgery is extremely difficult as Calot's triangle is often completely obliterated and the risks of causing injury to the CBD are high.

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)