What is the appropriate evaluation and management for a patient presenting with abdominal and lateral flank swelling due to suspected ascites?

Evaluation and Management of Abdominal and Flank Edema (Suspected Ascites)

Perform diagnostic paracentesis immediately in all patients with new-onset moderate to severe ascites (Grade 2 or 3) to determine the underlying cause and guide management. 1, 2

Initial Physical Examination

Assess for ascites using shifting dullness, which has 83% sensitivity and 56% specificity and is the most practical bedside technique. 1

• Percuss the flanks first when abdominal swelling is observed 1
• To test for shifting dullness: percuss the abdomen to identify the tympany-dullness interface, then have the patient roll to one side and observe if the dullness shifts to the dependent side 1
• If no flank dullness is present, the patient has less than 10% chance of having ascites 1
• Flank dullness indicates approximately 1,500 mL of fluid must be present before detection 1
• The fluid wave test is more specific but less sensitive and more cumbersome than shifting dullness 1

Grade the Ascites Severity

• Grade 1: Detected only by ultrasound; not clinically evident 1
• Grade 2: Easily identified by visual inspection and palpation; moderate symmetrical distension 1
• Grade 3: Profound distension of the abdomen (massive or tense ascites) 1

Confirmatory Imaging

Order abdominal ultrasound if physical examination is inconclusive, as it can detect ascites when volume exceeds 100 mL. 1

Mandatory Diagnostic Paracentesis

Perform diagnostic paracentesis in all patients with new-onset Grade 2 or 3 ascites or those hospitalized for worsening ascites or any cirrhosis complication. 3, 1

Essential Paracentesis Studies

Obtain the following from ascitic fluid:

• Cell count with differential: Neutrophil count >250 cells/µL diagnoses spontaneous bacterial peritonitis (SBP) 3, 2
• Albumin concentration: Calculate serum-ascites albumin gradient (SAAG) 3, 2
• Total protein concentration: Levels <1.5 g/dL indicate higher SBP risk 3, 2
• Culture: Inoculate at least 10 mL into blood culture bottles at bedside to enhance sensitivity 3, 2
• Triglyceride level: If fluid appears white/milky, measure triglycerides (>200 mg/dL confirms chylous ascites) 4

Paracentesis is safe with bleeding complications occurring in only about 1% of patients. 1

Interpret the SAAG to Determine Etiology

SAAG ≥1.1 g/dL indicates portal hypertension with 97% diagnostic accuracy, distinguishing portal hypertension-related causes from non-portal hypertension causes. 2

Portal Hypertension-Related (SAAG ≥1.1 g/dL):

• Cirrhosis accounts for 75-85% of all ascites cases 1, 2
• Cardiac ascites (distinguish by checking jugular venous distension and measuring BNP/pro-BNP: median pro-BNP 6,100 pg/mL in heart failure vs 166 pg/mL in cirrhosis) 2
• Portal vein thrombosis 3

Non-Portal Hypertension (SAAG <1.1 g/dL):

• Malignancy (perform cytology) 3, 1
• Tuberculosis (check ascitic fluid PCR for mycobacteria, adenosine deaminase, consider laparoscopy with peritoneal biopsy if risk factors present) 2
• Pancreatic disease 3, 1
• Nephrotic syndrome 1

Critical Pitfalls to Avoid

• Do not rely on physical examination alone for small volumes: Physical exam may miss ascites less than 1,500 mL 1
• Do not skip paracentesis: It is the most rapid and cost-effective diagnostic method 2
• Do not rely solely on fluid appearance: Turbid fluid can result from infection or tumor cells, not just chylous ascites, so always measure triglycerides if fluid appears milky 4
• Always inoculate blood culture bottles at bedside: This significantly enhances culture sensitivity for detecting SBP 3

Prognostic Implications and Referral

The development of ascites dramatically worsens prognosis, with 5-year survival dropping from 80% in compensated cirrhosis to 30% with ascites, and one to two-year mortality of 40-50%. 3, 2

All patients with new-onset ascites should be evaluated for liver transplantation, as this is the only intervention that improves survival in decompensated cirrhosis. 3, 2, 5