What is a Fistula
A fistula is an abnormal connection in the body that forms between two bodily structures that are lined with epithelial cells, which make up the epithelial tissue (epithelium) that helps protect and enclose internal organs and also makes up the outer surface of the body. Most often, a fistula forms between organs, blood vessels or abdominal tissues of the body, and are often the result of surgery or a disease process. Fistulas are known to form in many areas of the body, including the eyes, salivary glands, the bladder, rectum, esophagus and stomach.
There are many types of fistulas, some are minor and cause minimal problems, others are life-threatening. Some fistulas are congenital, meaning the problem is present at birth, but most develop later in life. They are often the result of a disease process, or a complication of surgery.
A fistula is categorized by the type of path it takes through the body. A blind fistula is open at one end only and creates a pocket. A complete fistula is more like a tunnel, with an opening at both ends. An incomplete fistula has an external opening to the skin, but does not connect with an internal organ.
An example of a congenital fistula is the pulmonary arteriovenous fistula. This is an abnormal connection between the arteries and veins of the lungs. With normal circulation, the blood without oxygen goes to the lungs where it "picks up" oxygen, and oxygenated blood then is pumped to the rest of the body by the heart. The pulmonary arteriovenous fistula allows oxygenated and deoxygenated blood to mix together, leading to some oxygenated blood being circulated to the lungs and poorly oxygenated blood being pumped to the body. The severity of the fistula determines how much oxygen is reaching the body and how much the patient is affected.
Diseases can cause fistulas. Crohn's disease, which causes inflammation of the bowel, and can slowly destroy the delicate tissues of the intestine, can lead to an anorectal fistula. This type of fistula allows stool to travel outside of the intestine, which leads to stool coming out of the body from a place other than the rectum, such as the vagina.
An obstetric fistula is a complication of a difficult childbirth, where blood supply is minimal or cut off completely to an area of abdominal tissue, often the bladder, uterus or intestine. When this tissue dies, it leaves a hole through which urine or stool can move, and the woman may experience stool leaking from her vagina or urine leaking from her anus. This type of fistula can lead to chronic infections and requires surgery to repair the damage, and is most common in countries where women may experience prolonged, obstructive labor where a cesarean section may not be easily obtained.
Surgically Created Fistulas
Surgically created fistulas should not be confused with a fistula that is an unexpected surgical complication. A surgically created fistula is intentionally created to benefit the patient. For example, a dialysis fistula, also known as a a cimino fistula or an AV fistula, is created surgically to provide access for hemodialysis in patients with end stage renal disease. This type of fistula is typically placed in the lower arm and connects a vein and artery for improved venous access with low pressure blood flow. Intentional fistulas are also used for the treatment of portal hypertension in the liver.
In general, the severity of a fistula and the problems caused by the fistula will determine the type of treatment that is necessary. The first step is testing to determine the size, shape and extent of the fistula. While most are tube shaped, some have branches from that tube, and others may have only one opening. Testing ranges from xrays and ultrasound to a barium enema. Other diagnostic tests can include CT scans or an MRI. For others, a colonoscopy may be necessary.
The path of the fistula, the location and the size all help determine the proper course of treatment. In some cases antibiotic therapy may be adequate, for most, surgery is required to fix the problem. In the vast majority of cases antibiotic therapy will be necessary to prevent local or even systemic infections.
Medline Plus. Fistula. Accessed November 2013. http://www.nlm.nih.gov/medlineplus/ency/article/002365.htm