A middle aged male with abdominal distension...

A middle-aged male with a history of IV drug use and alcohol abuse presents one evening complaining of abdominal distension and discomfort.  He reports that the distension has gotten progressively worse over the last few weeks and he now has some difficulty breathing as well. 

His vital signs are unremarkable:  Afebrile, BP 122/78, HR 92 , Sat 96 % on RA

His abdomen is distended and diffusely tender to palpation.

Some basic lab work is obtained:

... and the primary team also gets a CT of the Abdomen & Pelvis:

Interpret the CT. What is your differential diagnosis?  What would you do next?

Scroll down for the case conclusion.

 

 

 

 

 

 

 

 

Final diagnosis:  Chylous Ascites due to intestinal lymphangiectasia

Case Conclusion:  Diffuse abdominal free fluid was noted containing multiple fat-fluid levels, consistent with likely chylous ascites.  A paracentesis was performed (actually was the first test done) which returned a milky white fluid with a triglyceride level of > 1000 mg/dL confirming the diagnosis of chylous ascites.  The patient’s abdomen and pelvis CT did not reveal any obvious malignancies.  While a diagnosis of hepatitis C was found, the patient had no evidence of cirrhosis on liver biopsy.  A subsequent upper endoscopy demonstrated prominent small bowel lymphatics, suggesting a diagnosis of intestinal lymphangiectasia.  The patient’s low protein levels were consistent with an associated protein-losing enteropathy.

Learning Points

We often encounter patients with ascites in the emergency department.  While the lion’s share of patients we see are those with cirrhosis needing paracentesis for symptomatic dyspnea, abdominal discomfort or evaluation for spontaneous bacterial peritonitis, we should not forget that there are a wide variety of disease processes that may manifest with ascites.  In patients with ascites in general, the most important diagnostic tool is an abdominal paracentesis.  The gross appearance of ascitic fluid can help narrow the differential diagnosis.   Typically, we are familiar with the straw-colored fluid of cirrhotic ascites, but ascites may be bloody (malignant, hemorrhagic pancreatitis, perforated ulcer or traumatic tap), cloudy (infectious), or milky-white in the case of chylous ascites.   Occasionally, fluid may be so cloudy that it appears chylous. Such “pseudochylous” ascites is associated with bacterial infection, pancreatitis or perforated bowel [1].  The serum-ascites albumin gradient (SAAG), calculated by substracting the ascites albumin concentration from the serum albumin concentration, is a useful adjunct in differentiating ascites due to portal hypertension (such as in cirrhosis or congestive heart failure) as opposed to other causes [2].

Source:  Reference [1]

In addition to a diagnostic paracentesis, this patient had an abdominal CT scan performed. The differential diagnosis of abdominal free fluid on CT scan needs to be considered within the overall clinical picture.  In a patient with a history of IV drug use and Hepatitis C infection, ascites is the most likely etiology.  If the patient had a history of trauma or was hypotensive, blood would of been a consideration, although blood and ascites can generally be distinguished by the density of the fluid [see figure].  This patient’s CT had the rare finding of fat-fluid levels, which has been reported in two situations:  solitary chylous mesenteric cysts and chylous ascites [2]. 

Chylous ascites is an uncommon form of ascites due to the leakage of lipid-rich lymph into the peritoneal cavity.  It is diagnosed by the presence of a milky-appearing ascitic fluid with a triglyceride content > 200 mg/dL [3].  The lymphatic system is a one-way drainage system allowing return of interstitial fluids and proteins into the capillary system.  Most of the body’s lymph drains into the thoracic duct, a 38-45 cm long tract extending from the level of the L2 vertebra into the thoracic cavity, on its way to the vascular system[3]. More than 50% of the total body lymph originates in the gut and liver, where long-chain triglycerides are converted into monoglycerides and free fatty acids and absorbed in chylomicrons, leading to milky appearance of lymph.   

 Image source: Reference [3]

Image source: Reference [3]

Chylous ascites is an uncommon disease with a broad differential diagnosis.  Broadly speaking, it occurs as a result of traumatic injury or obstruction.  In developed countries, underlying malignancy (25%)  and cirrhosis (16%) are the most common etiologies.   Lymphatic anomalies, such as this case, are the most common cause in children, but are more rarely (9%) found in adults [3].  This patient was diagnosed with intestinal lymphangiectasia (aka Waldmann’s disease), a rare disorder of unknown etiology characterized by dilated intestinal lacteals. Patients with this disorder (usually children under 3 years of age, but occasionally adults) leak lymph into the small bowel lumen leading to malabsorption and protein-losing enteropathy. The resulting hypoalbuminemia results in the main manifestations of the disease:  lower extremity edema, anasarca, pleural effusion, and pericarditis while the lymphatic obstruction results in chylous ascites [4]. 

Table source: Reference [3]

Initial treatment of chylous ascites is medical management [3].  Medical management is based on the theory that decreased chyle flow will decrease ascites accumulation, and may eventually allow for spontaneous closure of the leak.   Patients are transitioned to a high protein and low-fat diet that is supplemented with short and medium chain triglycerides (MCT), as these are absorbed directly by the portal venous system rather than the lymphatic system.  MCT oil should be avoided in patients with advanced cirrhosis as narcosis and coma may occur.  For symptomatic patients presenting to the emergency room, the treatment is therapeutic paracentesis to relieve volume.  Unless the patient has underlying cirrhosis, post-paracentesis supplementation with albumin is not generally recommended [3].

Case Conclusion by Maia Dorsett (@maiadorsett)

References:

  1. Huang, L. L., Xia, H. H. X., & Zhu, S. L. (2014). Ascitic Fluid Analysis in the Differential Diagnosis of Ascites: Focus on Cirrhotic Ascites. Journal of Clinical and Translational Hepatology, 2(1), 58.
  2. Wachsberg, R. H., & Cho, K. C. (1994). Chyloperitoneum: CT diagnosis. Clinical imaging, 18(4), 273-274.
  3. Al-Busafi, S. A., Ghali, P., Deschênes, M., & Wong, P. (2014). Chylous ascites: evaluation and management. ISRN Hepatology, 2014.
  4. Vignes, S., & Bellanger, J. (2008). Primary intestinal lymphangiectasia (Waldmann's disease). Orphanet journal of rare diseases, 3(1), 1.