Chylous Ascites - Management, Signs and Symptoms

What Is Chylous Ascites?

Chyle is a milky fluid containing fat that drains the small intestine into the lymphatic system during digestion. Ascites is an accumulation of fluid in the abdomen. Chylous ascites (CA) happen when fat-rich lymph accumulates in the peritoneal cavity due to damage to the lymphatic system secondary to traumatic injury or obstruction. The ascitic fluid has a turbid or milky appearance due to the high triglyceride content. The triglyceride content is usually greater than 200 mg/dL (milligrams per deciliter).

What Is the Etiology of Chylous Ascites?

The etiology of chylous ascites has been classified as:

• Traumatic (blunt abdominal trauma).

• Congenital defects.

• Infections like abdominal tuberculosis.

• Malignancy includes lymphomas or metastasis from primary malignancy.

• The postoperative complication in abdominal surgery.

• Cirrhosis.

• Cardiogenic.

• Inflammatory.

• Pelvic irradiation.

• Peritoneal dialysis.

About two-thirds of all chylous ascites in developed countries are associated with abdominal malignancy and cirrhosis, whereas infectious diseases remain the primary etiology in developing countries. Chylous ascites can also be reclassified based on the portal and non-portal etiologies based on the presence or absence of disease conditions affecting the underlying portal system.

What Is the Epidemiology Behind Chylous Ascites?

Back in 1992, a big hospital associated with a university figured out that about 1 in 20,000 admissions over 20 years were due to chylous ascites (CA). But with better care and treatment for cancer patients leading to more people surviving, the number of CA cases has probably gone up. CA is a serious condition with high chances of death, depending on what is causing it (between 40 to 70 percent chance).

How To Classify Chylous Ascites?

The classification of chylous ascites is as follows:

1. True Chylous Ascites - Fluid with high glyceride content.

2. Chyliform Ascites - Fluid with protein related to fatty degeneration.

3. Pseudochylous Ascites - Fluid that is milky in appearance, which is not because of chyle but pus.

What Is the Pathophysiology of Chylous Ascites?

The main cause of chylous ascites (CA) is the disruption of the lymphatic system's normal flow. Lymph, which is rich in triglycerides (TGs), usually comes from the intestine, liver, and other abdominal organs. When CA happens, high lymphatic pressure, often due to conditions like portal hypertension, damages the lymphatic vessels, causing them to rupture and form CA.

The pathophysiology of CA can vary based on its cause, which can be divided into three main mechanisms:

1. Acquired Lymphatic Disruption: This can result from trauma or surgery, causing the lymphatic vessels in the abdomen to dilate and leak lymph into the peritoneal cavity. It can also occur due to increased lymph production and pressure in the hepatic veins, as seen in conditions like portal hypertension caused by cirrhosis.

2. Fibrosis of the Lymphatic System: This is commonly seen in cancers that block the normal flow of lymph from the gut. It leads to leakage of lymph into the abdomen due to dilated lymphatic vessels and fibrosis of lymph nodes.

3. Congenital Causes: Anomalies present at birth, such as congenital lymphangiectasia, can lead to the exudation of lymph into the peritoneal cavity, resulting in CA.

What Are the Clinical Signs And Symptoms?

• Painless and progressive abdominal distention.

• Weight gain.

• Shortness of breath due to increased abdominal pressure.

• Non-specific symptoms such as anorexia, malaise, diarrhea, edema, nausea, enlarged lymph nodes, early satiety, fever, and night sweats may be present.

• In patients with underlying cirrhosis, related symptoms like jaundice (yellow discoloration of the skin and eyes due to high bilirubin levels), palmar erythema (skin condition where the palms turn red), spider angiomas (swollen blood vessels found slightly beneath the skin surface with a central red spot and extensions which look like spider’s legs) of the chest and encephalopathy (a disease that affects the structure or function of the brain) may be seen.

How to Evaluate for Chylous Ascites?

Apart from the clinical signs and symptoms, detailed information on the history of malignancy, recent abdominal surgery, and underlying liver disease should be obtained to evaluate these patients.

• Abdominal paracentesis is the most important test in diagnosing chylous ascites. The fluid should be analyzed for cell count, gram stain, bacterial culture, glucose concentration, total protein, albumin, amylase, triglycerides, and lactate dehydrogenase. On examination of the ascitic fluid, it was found to have a milky, cloudy, and turbid appearance. Elevated ascitic fluid triglycerides are another parameter for the diagnosis of CA. In infectious diseases like tuberculosis, the acid-fast bacilli smear, culture, and PCR (polymerase chain reaction) should also be performed. ADA (adenosine deaminase), released during immune response in case of infectious diseases, can be detected in the fluid, which can also be used as an indirect marker for tuberculosis.

• The gold standard for diagnosing chylous ascites is the identification of chylomicrons using the lipoprotein electrophoresis test. Chylomicrons are ultra-low-density fat globules composed of protein and fat synthesized in the small intestine.

• Cytology and peritoneal biopsy are essential in diagnosing CA related to malignancy or tuberculosis.

• It is difficult to differentiate between chylous and clear ascites in CT (computed tomography) scans. Fat fluid level is a radiological sign for the diagnosis of CA. It is done after asking the patient to lie on their back for some time. Since the specific gravity of fat is less than that of water, a fat fluid level is formed.

• Lymphangiography and lymphoscintigraphy are used to visualize the body’s lymphatic system for any abnormality or leakage. Lymphoscintigraphy can accurately identify the leakage sites, and hence, they are more helpful in selecting patients for surgery. It is non-invasive but has technical challenges, whereas lymphangiography is invasive. It has complications like infection, pain, bleeding, and more. It can transiently worsen the condition due to the oily contrast medium used for the test.

What Is the Management for Chylous Ascites?

Management is mainly focused on symptomatic relief and treating the underlying cause. Treatment for chylous ascites includes dietary measures, pharmacological agents, and surgical interventions. Malignancies account for up to 85 percent of the atraumatic cases, and they usually have a poor prognosis. If the underlying etiology is malignancy, chemotherapy or radiation therapy must be promptly advised.

• Dietary measures include a high-protein and low-fat diet with medium-chain triglycerides (MCT). Coconut oil is a natural source of MCTs. Synthetic MCT oil is administered orally at a dose of 0.51 fluid ounces (15 milliliters) three times a day with meals. They can cause abdominal distension, nausea, and vomiting. Patients with CA associated with cirrhosis should be treated with a low-sodium diet and drugs such as Furosemide and Spironolactone; however, the use of MCTs in advanced cirrhosis can worsen the symptoms.

• Patients who do not respond well to the above measures should have bowel rest and be given total parenteral nutrition (feeding necessary fluids into a vein). Octreotide (somatostatin analog, which reduces portal pressure) has been beneficial in the management of chylous ascites.

• Orlistat inhibits the conversion of dietary triglycerides into fatty acids, thereby reducing the availability of fatty acids for absorption.

• Paracentesis (a procedure where a needle is inserted into the peritoneal cavity to obtain ascitic fluid) can provide temporary relief. However, reaccumulation of fluid may require repeated paracentesis. Complications can worsen the prognosis.

• In patients with CA related to surgery, supportive therapy can help resolve the condition. Early reoperation is indicated when the leakage site is prominent and the patient has a good prognosis.

• A chylous leak can be ligated with sutures and fibrin glue.

• Transjugular intrahepatic portosystemic shunts (TIPS), which reroutes blood flow in the liver, have been used successfully to treat chylous ascites.

• Laparotomy should not be used in children with chylous ascites unless they are unresponsive to other conservative management.

Conclusion

Chylous ascites are rare; the treatment outcome depends on the underlying etiology. Treatment strategies also vary for each patient. Sepsis is a potentially life-threatening complication associated with it. The prognosis is poor when it is related to malignancy. Pediatric patients with postsurgical and post-traumatic chylous ascites have a favorable prognosis. Consultation with a healthcare professional would provide further insight into the matter