What is a chyle fistula?
A chyle fistula is a condition where lymphatic fluid passes out of a lymphatic vessel and drains into a cavity within the body or into the exterior. It is a rare condition that is easily treated but can lead to death if no treatment is forthcoming. A chyle fistula is often associated with serious condition where it arises as a complication of diseases such as cancer or even after surgery. It is fairly silent (lack of symptoms) at the outset when it drains into internal cavities. However, it less commonly drains out onto the skin surface where it is more obvious.
Meaning of Chyle and Fistula
The terms chyle and fistule can be confusing and the condition chyle fistula is often termed a leaky lymphatic vessel.
- Chyle is the milky fluid containing fats and lymph which travel through the lymphatic vessels.
- Fistula is an abnormal tube-like passage between two points within the body or with one point on the skin surface.
Chyle fistula lymph leak
Normal Lymph Flow
The cells in our body are surrounded by tissue fluid. It serves as a medium for substances to move in an out of cells and the blood vessels. The fluid is clear and is constantly replenished from arteries carrying blood to an area. The blood cells stay in the artery but the fluid which is rich in oxygen and nutrients pass out into the tissue spaces. From here the cells take up and use the oxygen and nutrients from the tissue fluid. Carbon dioxide and wastes pass out into the tissue fluid.
Some of this tissue fluid empties into a vein and is carried away but some tissue fluid is retained at the site. It is the lymphatic vessels that carry away this residual fluid. It is also able to transport substances that may not be suitable for transportation by the blood, such as fats, very large proteins and even microbes like bacteria. The tissue fluid that is now in the lymphatic vessel is known as lymph. It is eventually emptied back into the bloodstream at a few sites in the body.
Leaking lymphatic vessel
A break in a lymphatic vessel can occur for any number of reasons. It is more often damaged during surgery or with injury. However, these vessels are easily repaired on its own in the body usually without the need for any medical intervention. As it is healing, the lymph can flow through alternate routes in the network of lymphatic vessels. However, sometimes there are no alternate routes which will allow for normal lymphatic drainage. The lymph can therefore seep into tissue and eventually lead to the formation of a hollow passage in the tissue known as a fistula. By way of this fistula, the lymph laden with fats (collectively known as chyle) empties into the chest or abdominal cavity or even on the skin surface.
Chyle fistula causes
The causes of a chyle fistula varies and overall it is rare. A damaged or partially severed lymphatic vessel can heal quickly in most instances. It can arise due to the following causes :
- Traumatic rupture of the lymphatic vessel.
- Surgical damage of the lymphatic vessel, which is more likely to lead to a chyle fistula during head and neck surgery.
- Diseases of the lymphatic vessels.
- Cancer that involves the lymphatics.
- Chronic and severe inflammation associated with certain diseases like cirrhosis (liver), pancreatitis (pancreas) and tuberculosis (lungs).
- Idiopathic (unknown reasons) especially affecting the space around the heart (chylopericardium)
Chyle fistula symptoms
Apart from the symptoms of the causative condition, more specific symptoms of a chyle fistula depend on where the fluid is draining. There is often no symptoms at all until sufficient fluid accumulates in the cavity. Drainage onto the skin is very rare and here the condition would be easily seen. Chyle commonly drains into the thoracic (chest) cavity or abdominal cavity where it is known as a chylothorax or chyloperitoneum respectively. The symptoms in both these conditions are a result of a fluid build up and compression of the organs in the thoracic and abdominal cavity. A very rare form is chylopericardium where chyle accumulates around the heart only.
The symptoms depend on the amount of fluid that has accumulated in the thoracic (chest) cavity and the degree to which the organs are compressed.
- Difficulty breathing
- Fluid accumulation around the lung (pleural effusion)
- Impaired heart function as the heart does not fill as normal
The symptoms that are seen with chyloperitoneum are also dependent on the amount of fluid that accumulates in the abdominal cavity. With various organs from different symptoms in the abdominal cavity, the symptoms may vary to some degree.
- Easily satisfied even with small bites of food
- Loss of appetite
- Abdominal pain
- Abdominal distension
- Difficulty breathing in severe cases
Chyle fistula diagnosis
The symptoms of a chylothorax and chyloperitoneum are non-specific. Many other more common conditions will cause these symptoms. Fluid from the pleural cavity (around the lung) and abdominal cavity needs to be extracted. These processes are known as thoracentesis (thoracic cavity) or paracentesis (abdominal cavity) respectively.The fluid is then sent for testing to identify its composition. Chyle is an odorless, milky white fluid which is sterile meaning that there are no microbes present.
Chyle fistula treatment
The treatment of a chyle fistula depends on several factors. It is possible for it to heal on its own without any treatment in some cases although this will require a change in diet. Drugs and surgery are reserved for cases that are severe and extensive where dietary change alone will not be effective. Fluid drainage (thoracentesis and paracentesis) is not a suitable option for repeated removal of fluid in the long term.
Chyle is largely a fatty fluid since fats absorbed from the gut travel through the lymphatics. A diet without fats (fat restriction) may be helpful to reduce chyle formation and allow the damaged lymphatic vessel to heal. Total parenteral nutrition (TPN) is where nutrition is administered directly into the vein thereby passing the gut. This also gives the lymphatic vessels time to heal and possibly close off on its own.
Octreotide is a drug that mimics the hormone somastatin. It is a powerful inhibitor of several hormones like growth hormone. Frequent administration of this drug may help close leaks in malignancy.
There are two main surgical procedures considered for a chyle fistula. Surgery is not relevant for every case of a chyle fistula.
- Ligation where the leak is surgically closed.
- Peritoneovenous shunts where chyle from the abdomen is drained into a vein thereby returning it to the circulation.