What Is a Gastrointestinal Fistula and What Causes It?

Gastrointestinal fistula manifests with symptoms such as diarrhea, nausea, rectal bleeding and even fever and excruciating abdominal pain. The prognosis is highly variable.
What Is a Gastrointestinal Fistula and What Causes It?

Last update: 03 May, 2021

A fistula occurs when a connection is formed between an organ and another structure, usually secondary to injury. A gastrointestinal fistula is very common in patients with Crohn’s disease, as up to 35% of them develop at least one at some point in their lives.

On the other hand, this type of health issue is also typical in patients who have undergone a surgical procedure in the abdomen. According to studies, up to 85% of fistulas arise as a side effect of these practices. If you want to know everything about gastrointestinal fistulas and how to deal with them, you’re in the right place!

Types of gastrointestinal fistulas

Scientific studies classify fistulas according to their place of occurrence, so they can be external or internal. Internal fistulas communicate two organs with each other, while external fistulas communicate directly or indirectly with the body surface. Furthermore, depending on the number of connections they generate, they can also be simple or complicated.

Based on their site of appearance, there are 4 different types of gastric fistulas:

  • Esophageal, gastric and duodenal
  • In the small intestine
  • In the colon
  • Any of the above that has drained through a wall defect larger than 20 square centimeters (8 in).

The last term is noteworthy. Fistulas, being openings, allow the escape of liquids present in the gastrointestinal tract. Based on this parameter, a fistula can be low-flow (drains less than 500 milliliters per day) or high-flow (drains more than 500 milliliters per day).

Human digestive system.
Any section of the human digestive tract can produce a fistula.

What are the symptoms of gastrointestinal fistula?

The Drugs.com portal indicates some of the most common symptoms of the presence of a gastrointestinal fistula in patients. Among them we find the following:

  • Abdominal pain or gassy indigestion
  • Diarrhea
  • Weight loss, nausea, and vomiting
  • Heartburn
  • Fluid leaking through a wound in the abdomen

With an internal fistula the patient may also experience rectal bleeding, infection in the bloodstream, malabsorption of nutrients, dehydration and a worsening of underlying health issues. On the other hand, some don’t generate symptoms; it all depends on the above-mentioned parameters and the individual’s state of health.

Possible complications

If the patient suffers from heavy rectal bleeding, uncontrolled vomiting and nausea or an enlarged abdomen, the patient must seek medical help urgently. Some fistulas can be life-threatening if associated with a bacterial infection in the surrounding tissue.

Despite advances in medicine, research sources show that 25 to 50% of patients with enterocutaneous fistulas eventually die. This data is not completely fair though, as we’re usually referring to people who are already in poor health.

Main causes of gastrointestinal fistulas

Medical studies explore the main causes of gastrointestinal fistula. We’ll tell you about their findings in brief in the following lines.

Surgical procedures

As mentioned above, 75-85% of gastrointestinal fistulas are the result of a complication following abdominal surgery. It’s difficult to obtain a specific figure, as it depends on many factors, but all authors agree on the same thing: more than half of them arise in the postoperative period.

Diverticular diseases

The occurrence of diverticula that affect the large intestine in a severe form can also trigger the appearance of fistulas. These are located as connections with intra-abdominal organs (the bladder, for example).

Crohn’s disease

Crohn’s disease causes prolonged chronic inflammation of certain parts of the digestive tract. This leads to abdominal pain, fever, fatigue, constipation and bleeding in the stool. In particular, up to 35% of people with this pathology develop fistulas.

Malignant processes

The occurrence of cancerous tumors in the intestine and adjacent organs promotes fistulization processes. Radial extension of a mass in the mucosa of the digestive tract and a destruction of normal tissue promotes this connection.

How can it be diagnosed?

The National Library of Medicine of the United States lists some of the most effective diagnostic methods for detecting a gastrointestinal fistula. These include the following:

  • Esophagography: a series of X-rays taken to evaluate the condition of the esophagus, stomach and small intestine. A direct search for the fistula is performed.
  • Barium enema: a special x-ray of the large intestine that includes the colon and rectum.
  • CT scan: this tool is used to search the abdomen for the fistula between the intestinal loops or areas where previous infections have occurred.
  • Fistulogram: uses a form of real-time x-ray called fluoroscopy and contrast material (barium-based) to generate images of an abnormal passageway inside the body.

Although all diagnostic methods are valid, the fistulogram is the technique that provides the most relevant medical information. Thanks to the fistulogram, in addition to detecting the fistula itself, doctors can evaluate the state of the lesion and its extension.

A man undergoing a medical exam.
Serial X-rays are successive X-ray films taken to cover a large part of the gastrointestinal tract, from the esophagus to the rectum.

Available treatments

There are two variants of treatment: conservative and surgical. In the first case, the doctors usually prescribe antibiotics to prevent the development of severe bacterial infections. In addition, if the fistula is the result of Crohn’s disease, the patient must receive immunosuppressive drugs.

Other conservative approaches include the use of fibrin glues to close the fistula in a minimally invasive manner and intravenous nutrition of the patient while it heals. The success rate of this approach isn’t very high, so it usually results in surgical excision of the affected area.

Gastrointestinal fistula: a complication of an underlying issue

In conclusion, a gastrointestinal fistula is a difficult clinical entity to approach. It usually arises as a by-product of a previous complication, either surgery or prolonged bowel disease.

Therefore, the prognosis depends on the primary health issue and the patient’s personal situation. Quality of life is highly affected and interferes with the basic treatments that the patient is undergoing.

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