Chylous ascites

Other Names: Congenital chylous ascites Chylous ascites is a rare form of ascites caused by accumulation of lymph in the peritoneal cavity, usually due to intra-abdominal malignancy, liver cirrhosis or abdominal surgery complications, and present with painless but progressive abdominal distension, dyspnea and weight gain.

Cause

This usually occurs due to trauma and rupture of the lymphatics or increased peritoneal lymphatic pressure secondary to obstruction. The underlying etiologies for CA have been classified as traumatic, congenital, infectious, neoplastic, postoperative, cirrhotic or cardiogenic. Since malignancy and cirrhosis account for about two-thirds of all the cases of CA in Western countries, in this article we have attempted to reclassify CA based on portal and non-portal etiologies.

Pathophysiology

Several mechanisms have been proposed for the formation of CA based on the underlying etiology.

Pathophysiology in portal hypertension CA is commonly associated with PHTN, which is defined as elevation of the [hepatic venous pressure]] gradient (HVPG) to >5 mmHg. PHTN is caused by a combination of increased resistance to the passage of blood flow in the liver and increased splanchnic blood flow secondary to vasodilatation within the splanchnic vascular bed. The normal range for HVPG is 1–5 mmHg. PHTN is present if the HVPG is ≥6 mmHg, and a HVPG ≥12 mmHg is associated with increased risk for variceal bleeding and the development of ascites. The underlying pathophysiology of CA formation due to portal causes is not well understood. It has been proposed that increased caval and hepatic venous pressures cause a large increase in the production of hepatic lymph. Elevated lymphatic pressure secondary to PHTN can cause endothelial compromise or rupture of serosal dilated lymphatic channels and leads to CA formation. Cardiovascular disease, such as right-sided heart failure, constrictive pericarditis and dilated cardiomyopathy, are important causes of posthepatic PHTN, which may cause CA by increased lymph production and high resistance to lymphatic drainage due to central venous hypertension.

Pathophysiology of non-portal etiologies Several different mechanisms may be involved in CA formation in the setting of non-portal etiologies. These include exudation of lymph material through the walls of acquired or congenital dilated retroperitoneal vessels (megalymphatics) into the abdominal cavity through a fistula into the peritoneal cavity.

These megalymphatics may also form secondary to acquired thoracic duct obstruction from trauma, resulting in direct leakage of chyle through a lymphoperitoneal fistula. Also, malignancy may cause fibrosis of the primary lymph node that may eventually obstruct the flow of lymph from the gut to the cysterna chyli, resulting in leakage from the dilated subserosal lymphatics into the peritoneal cavity. Over a period of time, this increased pressure in the lymphatic system can result in deposition of collagen in the basement membranes of the lymphatics that further impairs the absorptive capacity of the gut mucosa.

Symptoms

CA usually presents with painless and progressive abdominal distention over a course of weeks to months. Studies have reported that the most common symptom is abdominal distension (81%), followed by pain or peritonitis in 11% of the cases. Patients may also complain of symptoms such as weight gain and shortness of breath, resulting from the 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, clinical features such as jaundice, palmar erythema, spider angiomas of the chest, and encephalopathy may be seen. History of malignancy, recent abdominal surgery, underlying liver disease, relevant family and social history (travel) should also be included in the evaluation of these patients.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Ascites(Accumulation of fluid in the abdomen)
• Lymphedema(Swelling caused by excess lymph fluid under skin)

30%-79% of people have these symptoms

• Subcutaneous nodule(Firm lump under the skin)

5%-29% of people have these symptoms

• Abnormal intestine morphology(Abnormality of the intestine)
• Glaucoma

Diagnosis

• The diagnosis of CA is based on the distinct characteristic of the ascitic fluid which includes a milky appearance and a triglyceride level of >200 mg/dL.
• Cytology and peritoneal biopsy are important diagnostic tools in the work-up of CA. A positive fluid cytology has a high correlation with presence of peritoneal carcinomatosis, with 96.7% of patients demonstrating positive cytology.
• Laparoscopy can be used as a diagnostic tool, as well as a therapeutic tool. It is an accurate method for direct inspection of the peritoneal cavity and to obtain biopsy samples of suspected sites for pathology. It is especially useful in cases for which the etiology of ascites cannot be established
• Computed tomography (CT) of the abdomen is a useful modality to identify abdominal masses and lymph nodes that may be present in some cases of CA .
• Lymphangiography and lymphoscintigraphy are modalities that can detect abnormal retroperitoneal, nodes, fistulas or leakage from lymphatic channels. They can also determine the patency of the thoracic duct. They are particularly useful in selecting patients that are suitable candidates for surgery.
• Lymphangiography is an important technique for the detection of lymphatic leaks. Studies have reported a detection rate of 64–86% for leakage sites in patients with chylothorax and CA.

Treatment

Treatment options for CA include dietary measures, use of pharmacological agents and surgical or percutaneous interventions in some select cases . The treatment modalities are targeted to provide symptomatic relief, with a focus to treat the underlying disease etiology causing CA. Malignancies account for up to 85% of cases of atraumatic CA in adults, and the presence of CA in malignancies usually predicts a poor prognosis.If the etiology is an underlying malignancy, modalities such as surgery, chemotherapy or radiation therapy should be instituted promptly.

Surgery may be an option in certain select cases. In patients with postoperative chylothorax and CA, indications for surgery include chylous leak >1000 mL/d for >5 days or a persistent leak for >2 weeks despite optimized conservative management. Surgery may also be considered in clinical scenarios associated with development of serious nutritional or metabolic complications

Dietary measures

• For symptomatic treatment of CA, a high-protein and low-fat diet with medium-chain triglycerides (MCT) is recommended.
• Patients with CA associated with cirrhosis should be treated with a low-sodium diet along with diuretics, such as furosemide and spironolactone.
• Patients who do not respond to the above measures should have bowel rest to reduce lymph flow and should be started on total parenteral nutrition (TPN).

Medical therapy Orlistat is a reversible inhibitor of gastric and pancreatic lipase and prevents the conversion of dietary triglycerides into free fatty acids in the intestinal lumen, thereby reducing the availability of fatty acids for absorption. Somatostatin reduces portal pressure by inhibiting glucagon and vasodilatation mediated by other splanchnic intestinal peptides. Etilefrine is a sympathomimetic drug used to treat postural hypotension. It has also been used successfully in the management of postesophagectomy CA with thoracic duct injury in patients with esophageal cancer.

Percutaneous embolization CA can also be managed by lymphangiography along with adjunctive embolization techniques that include direct percutaneous injection of glue into the leakage site or into a nearby lymph node.

Surgery If the above conservative management is not successful in treating CA, surgical interventions may be beneficial, especially in cases where CA is secondary to malignancy or postoperative and congenital causes. Laparotomy may be performed for fistula closure, bowel resection, or insertion of a peritoneovenous shunt. As discussed earlier, preoperative lymphangiography or lymphoscintigraphy is helpful in identifying the anatomical location of the leakage or the presence of a fistula.

Prognosis

As discussed earlier, CA is associated with mortality rates of 40–70% and an even higher morbidity rate depending on the underlying etiology. However, with the advent of superior chemotherapy regimens such as rituximab with combination chemotherapy, and monoclonal antibodies, there has been a marked improvement in survival rates and resolution of symptoms, especially in patients with malignancies such as lymphomas. Prior to the development of these new chemotherapy regimens, chylous effusions associated with lymphomas were associated with a dismal prognosis, with more than 90% of patients dying within 3 months of diagnosis.

NIH genetic and rare disease info

• NIH info on Chylous ascites

Chylous ascites is a rare disease.

Chylous ascites Resources
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