Lymphatic Leakage: An Overview

What Is Lymphatic Leakage?

When a lymph vessel gets injured, the lymph flowing through the vessel leaks into its surroundings; this is called lymphatic leakage. The vessel might get injured due to trauma or surgery, or it can be a birth defect (congenital). Most often, a lymphatic leakage occurs postoperatively after a lymph node dissection (removal of lymph nodes), leading to lymphatic fistula, chylous ascites, chylothorax, etc.

What Is Lymph and Lymph Node Dissection?

• When blood is circulating in the body, a portion of blood plasma escapes through the thin walls of blood vessels into the surrounding tissues. This fluid is called lymph; it needs to be circulated back into the main bloodstream to prevent fluid imbalance. This is done by the lymphatic system. The system comprises lymph, lymphatic vessels, lymph nodes, lymph organs, and lymphatic ducts.

• Lymph is a clear-to-white fluid that contains white blood cells, proteins, fats with high molecular weight, cancer cells, bacteria, viruses, etc.; similar to how blood flows in our body through blood vessels, and lymph also flows throughout the body in lymph vessels.

• A lymphatic vessel starts as small capillaries at the extreme ends of the body and starts collecting lymph. A few capillaries join to form a lymph vessel, and the lymphatic vessels join to form a lymphatic duct. The body has two major lymphatic ducts- the right lymphatic duct and thoracic duct (on the left side), both of which drain the lymph into their related veins.

• The unique feature of the lymphatic system that differentiates it from the nervous and circulatory system is that it is one way; the vessels carry lymph from all the organs and drain it into the two major veins, which then empty it into the heart.

• The lymphatic vessels are punctuated at intervals by small masses of lymph tissue called the lymph node. The lymph node is a secondary lymphoid organ that acts as a filter; they destroy and dispose of the disease-causing cells. The body has around 600 lymph nodes scattered all over the body, especially in the neck, groin, armpit, etc.,

• During the surgical removal of any malignant tumor in the body, the surgeon also removes the underlying lymph nodes to prevent the spreading of cancer to other body parts; this is known as lymph node dissection.

Failure to meticulously ligate (tie-up) the connecting vessels after the lymph node dissection will leave the lymphatic vessel open, causing lymphatic leakage.

What Are the Symptoms of Lymphatic Leakage?

Lymphatic leakage is a complication rather than a disease itself, so a congenital defect or trauma, or injury to the lymphatic vessels during surgery are potential causes for lymphatic leakage. Generalized symptoms of lymphatic leakage are loss of fluid (containing lymphocytes, fats, and immunoglobulins), dehydration, nutritional deficiency, and immunodeficiency. Because the fluid is leaking into the body, it will cause swelling at the site of the leakage, followed by compression of vital organs. Occasionally, an itchy erythematous rash is seen if the leakage occurs in the abdomen. Depending on the location and the type, lymphatic leakage can be of different types; they are-

• Lymphatic Ascites- When the lymph leaks into the peritoneal cavity (space in the abdomen that contains the intestine, stomach, and liver) due to the damage of underlying lymphatic vessels, it is known as lymphatic ascites. It is occasionally seen after an appendectomy or as a post-surgical complication in surgeries done for endometrial and cervical cancer.

• Lymphocele- It is seen under a healing wound and is often asymptomatic; the leaked lymph forms a cyst which will resolve on its own without any treatment. However, in a few cases where the lymphocele measures more than 5 cm, it will cause pain and infection that might need medical intervention. Symptomatic lymphoceles occur after surgeries in the pelvis, armpit, neck, and aorta.

• Lymphorrhea- It is a condition where the lymph leaks outside the body through an open wound and is seen in vascular reconstructive surgeries.

• Lymphatic Fistula- A fistula is an abnormal connection between two body parts, and when this occurs between the lymphatic vessel and an organ that it is not supposed to be connected to, like the urinary bladder, gastrointestinal tract, and uterus, it is known as a lymphatic fistula. They are common after lymph node dissection in urologic, gynecologic, and dermatologic cancers.

• Chylous Ascites- It is often assumed that lymph contains only lymphocytes and other immunity-related elements, but the lymph collected from the small intestine contains fat molecules, which give it a milky appearance. Lymph rich in fat molecules is known as chyle and is transported to the veins through the thoracic duct. When an injury happens to the thoracic duct during surgery or trauma, the chyle will leak into the peritoneum causing chylous ascites.

• Chylo Retroperitoneum- When chyle leakage happens in the retroperitoneum, it is known as chyloretroperitnum and is seen after lymph node dissection for testicular cancer.

• Chylothorax- As mentioned before, chyle drains into the thoracic duct. The thoracic duct is the main lymphatic vessel that measures around 45 cms and starts at the lower abdomen, passes through the diaphragm in between the lungs, and extends upwards to the neck, where it drains into the left internal jugular vein (a very important vein collecting blood from face and neck). If the thoracic duct injury happens near the lungs above the diaphragm, the chyle (lymph mixed with fat) will leak into the pleural space (space that exists between the lungs), causing chylothorax.

• Chylorrhea- It is similar to lymphorrhea, but instead of lymph, chyle exudates through the open wound.

Patients with symptomatic lymphatic leakage have a swollen stomach with abdominal fullness, pain, nausea, vomiting, and malnutrition. All these symptoms amplify after the patient eats food; this is the initial indication for lymphatic leakage diagnosis.

How Is Lymphatic Leakage Diagnosed?

Clinical symptoms help in the initial diagnosis; additional examinations include an oral contrast test, computerized tomographic (CT) scan, lymphangiography, lymphoscintigraphy, and laboratory examinations.

How Is Lymphatic Leakage Treated?

Conservative and surgical treatments are the available options for lymphatic leakage, most clinicians prefer conservative treatment first, but there is a popular belief that it would be in the patient's best interest to opt for surgical intervention after diagnosis to avoid metabolic complications.

Conservative therapy includes-

• Diet control with a high protein and medium-chain triglyceride diet.

• Medication with diuretics, vasoconstrictors, pancreatic lipase inhibitors, vasoconstrictors, somatostatin analogs, etc.

• Paracentesis (a procedure that removes peritoneal fluid with a slender needle).

• Sclerotherapy (is often used to treat lymphoceles by injecting ethanol to dissolve the lymphatic fluid).

Surgical therapy is indicated if the leakage volume is more than 1000 ml/day. Different approaches are used based on the type and location of the leakage; some of them are-

• Peritoneovenous Shunt- The principle behind this procedure is to reroute the leaking lymph or chyle (that is causing ascites) into the venous system by placing a shunt (a hollow tube) with a one-way pressure valve. It is the preferred method of drainage for lymphatic and chylous ascites.

• Lymphatic Embolization- A sophisticated technique that can be used for different kinds of lymphatic leakages, notably for lymphocele and chylothorax. For a lymphocele, embolization is done by packing micro coils and fibrin glue into the cysts, forming an embolus (a solid mass); this essentially blocks the lymph flow into the cyst, thereby redirecting the lymph into the vessel and shrinking the lymphocele.

Thoracic duct embolization is a little more complicated. First, the location of the leak is identified using lymphangiography, followed by catheterization- this will allow the surgeon to place the miro coils at the leakage site, the coils envelop the thoracic duct, then the surgeon will inject a glue (fibrin or NBCA) that will hold the coil together. Once the thoracic duct is successfully wrapped with the micro-coil, the surgeon will remove the catheter.

• Duct Ligation- The idea behind this procedure is to tie up the open ends of the severed thoracic duct, which will trigger anastomoses between the open ends and with the surrounding tissue. It is an open procedure and is always done from the right side under general anesthesia.

• Super microsurgery- The underlying principle is the same as duct ligation; instead of open surgery, super microsurgery uses highly delicate microsurgical instruments (30 to 80 micron needles) to accomplish anastomoses.

Regardless of the approach, the goal of the surgical approach is to completely stop the lymphatic leakage, and the surgeon will choose the technique after careful evaluation and investigations.

What Are the Complications of Surgery?

• Identifying the location of the leak is critical to managing lymphatic leakage. This is a complication in itself because the lymphatic vessels, including the thoracic duct, are not as well defined as their associated blood vessels.

• In the path to identify the location, the surgeon will have to insert the needle multiple times, which will damage the surrounding structures; for example- a bile leak from the liver has been reported after the Chiba needle insertion into the thoracic duct.

• The glue used in embolization and ligation occasionally causes pulmonary embolism. There is also the possibility of persisting ascites (swelling of the abdomen) after surgery.

• Nevertheless, surgery for lymphatic leakage has a 90 % success rate, with patients not experiencing any recurrent symptoms.

Conclusion:

The success of managing lymphatic leakage depends on early detection. Conservative treatment options resolve the issue in almost 70 % of the patients. However, surgery should be considered as an early treatment option for patients having continuous lymphatic leakage for more than five days to avoid metabolic complications that will lead to nutritional deficiency and poor immunity and subject the patient to a painful and prolonged hospital stay. Biweekly follow-up for one to two months, then monthly for six months, is mandatory to address post-op complications and observe prognosis.