From the Guidelines
For a patient with ascites of unknown origin, I recommend a comprehensive workup that includes both diagnostic and laboratory tests, starting with a thorough history and physical examination, and prioritizing abdominal paracentesis to analyze the ascitic fluid, as this is crucial for identifying the underlying cause and guiding treatment, as emphasized by the most recent guidelines 1. The diagnostic workup should include:
- Abdominal paracentesis to analyze the ascitic fluid, including cell count with differential, albumin, total protein, glucose, LDH, amylase, cytology, Gram stain, and culture, as recommended by 1 and 1.
- Calculation of the serum-ascites albumin gradient (SAAG) to differentiate between portal hypertension (SAAG ≥1.1 g/dL) and non-portal hypertension causes (SAAG <1.1 g/dL), as suggested by 1 and 1.
- Blood tests, including complete blood count, comprehensive metabolic panel, coagulation studies, serum albumin, and tests for liver disease (hepatitis serologies, iron studies, ceruloplasmin, alpha-1 antitrypsin), to identify potential underlying causes.
- Imaging studies, such as abdominal ultrasound with Doppler, to assess the liver, portal vein, and for masses, and consider CT or MRI of the abdomen and pelvis if ultrasound is inconclusive, as recommended by 1.
- Additional tests, such as ascitic fluid adenosine deaminase and mycobacterial culture for suspected tuberculosis, and ascitic fluid amylase and lipase for possible pancreatic disease, should be guided by the clinical presentation and initial test results, as suggested by 1. The most critical step in the diagnostic workup is the prompt performance of abdominal paracentesis, as it allows for the identification of spontaneous bacterial peritonitis (SBP) and other complications, and guides the initiation of appropriate treatment, as emphasized by the guidelines 1.