What Are Fistula and Chyle?
An abnormal connection between the two body parts, an organ, blood vessels, or any other structure, is termed a fistula. This usually results due to injury. Sometimes some infection or inflammation can also be a reason for the formation of a fistula. Most of the fistula is removed by surgery.
Chyle means juice in Greek, it is a milky or light pink fluid that contains fat globules (droplets), and it gets drained from the lacteals of the small intestine into the lymphatic system during the process of digestion. The main function of chyle is to provide required nutrients to the body tissues. Chyle is alkaline in nature.
The lymphatic fluid which is produced in the human body is passed through two channels, the thoracic duct, and the right lymphatic duct. Lymphatic fluid (chyle) is composed of fats, proteins, chylomicrons (esterified monoglycerides, fatty acids with cholesterol and proteins), electrolytes (sodium, calcium, potassium chloride), and glucose. The production of this fluid is around two to three liters per day. The volume of the fluid depends on the diet, mobility of the individual, intestinal function, respiration, and positive intra-abdominal pressure.
What Is a Chyle Fistula?
Chyle fistula is a rare but potentially serious and morbid condition. A leakage of lymphatic fluid from the lymphatic vessels, accumulating in the thoracic or abdominal cavity but presenting externally as a fistula, is defined as a chyle fistula. These fistulas most commonly occur secondary to any lymphatic disease or malignant conditions which involve the abdomen, neck, and the thorax. These can result due to venous hypertension in patients with superior vena cava syndrome or thrombosis in the vena cava.
How Does Chyle Fistula Occur?
Around 60 % of chyle fistulas are caused due to lymphoma, 25 % are by any kind of trauma, and other causes take the remaining 15 %. In most cases, the fistula occurs on the left side of the human body, where the thoracic duct enters the base of the neck, and then the duct travels to empty into the subclavian vein. These chyle fistulas can result in dehydration, delayed healing, immunosuppression, and malnutrition.
What Are the Signs, Symptoms, and Clinical Features of a Chyle Fistula?
The following are the signs and symptoms of Chyle fistula:
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Malaise (a general feeling of discomfort and pain).
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Anorexia (eating disorder).
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Abdominal pain and discomfort.
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Shortness of breath occurs due to abdominal distention and pressure on visceral structures and the diaphragm.
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Tachypnea (abnormally rapid breathing) and chest pain.
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Pleural effusion (water in lungs, build-up of excess fluid in between lungs and pleural layer).
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Decreased cardiac preload (occurs due to impaired atrial contraction and increased heart rate).
Due to loss of protein, fat and fat-soluble vitamins, trace elements, and lymphocytes, the following conditions occur:
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Hypovolemia (a condition in which liquid volume in the blood is too low).
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Electrolyte imbalance (a condition in which there is an imbalance of body electrolytes that occurs as a result of losing a large number of bodily fluids).
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Malnutrition (a condition in which the body is deprived of vitamins, minerals, and necessary nutrients).
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Immunosuppression (a condition in which the body’s natural immunity is suppressed).
How Is the Diagnosis Made for Chyle Fistula?
Because of the low incidence of chyle fistulas, a high suspicion index is required; diagnosis is usually made after the individual has recovered from prior surgery and started having food.
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History is taken.
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Physical examination.
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Thoracentesis - A procedure to remove fluid or air around the lungs is done. A needle is used to aspirate the chest wall into the pleural space. The fluid which is aspirated is tested for chyle. The presence of chylomicrons and triglycerides is checked.
What Is the Treatment Provided for Chyle Fistula?
For the treatment, the following points are taken into consideration:
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Etiology of Fistula: They are secondary to malignancy and are more difficult to treat. The amount of output from fistulas, the more the output, the more physiologic derangements occur which may require aggressive therapies.
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Site: Fistula in the neck are easier to access rather than the abdomen and thorax.
The treatment can be divided into two parts:
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Non-operative Therapy:
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Nutritional Intervention: Use of an internal diet and fat restriction. MCTs (triglycerides) usage as they are absorbed directly from the gut into PVS (port venous system).
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TPN (Total Parenteral Nutrition): Full caloric and nitrogenous support that allows rest to the bowel, which achieves a decreased chyle flow, and thus healing occurs.
2. Other Therapy and Treatments:
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Octreotide is successful in treating chyle fistulas. Studies found it to be effective in treating chyle leaks after neck dissection surgery.
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A systematic review of meta-analysis comparing octreotide with oral dietary modifications was done.
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Somatostatin is an inhibitory hormone found in the human body. Somatostatin and its derivatives are highly effective in the management of chyle fistula with very few side effects. It decreases the portal blood flow and gastrointestinal secretions; these drugs efficiently reduce lymphatic flow through the thoracic duct and decrease fistula volume.
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TIPS (transjugular intrahepatic portosystemic shunt) - It is proven to be a successful treatment in cases of chylous ascites, which occurs due to cirrhosis.
3. Surgical Therapy:
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The surgical approach is taken when conservative therapy fails. The surgical ligation procedure is generally successful; the lead is identified by scintigraphy. The leak vessels are ligated, and in some cases, muscle flaps are used to ligate the leaks. Sometimes other forms of irritants are used to plug the leak, like fibrin glue and tetracycline.
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Lymphatic interventions like direct leakage scleropathy or embolization.
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Percutaneous afferent lymphatic vessel embolization.
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Percutaneous afferent lymphatic vessel disruption.
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Transafferent nodal embolization.
What Happens If the Chyle Fistula Remains Untreated?
If the chyle fistula remains untreated, it can turn fatal. Individuals may die due to severe fluid and electrolyte imbalance abnormalities, malnutrition and severe infections like peritonitis and empyema.
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Iatrogenic (disease caused by medical examination or treatment taken) complications can occur.
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Complications from shunt placement, shunt failure, and fluid overload can occur.
Conclusion:
Chyle fistula is a complication that results after a neck or thoracic surgery. Chyle leakage may lead to a prolonged hospital stay due to primary hyponatremia (low concentration of sodium in the blood), hypocalcemia (low calcium in the blood), and hypoproteinemia (lower levels of protein in the blood). This leak also disrupts the biochemical environment that would help in wound healing. This may cause delayed wound healing, wound infection, fistula formation, wound breakdown, infection, and sepsis. Various management steps are taken, like parenteral nutrition, diet restriction revision surgery, and pressure dressing.
