What initial bloodwork is recommended for a patient with a history of cirrhosis (liver scarring) presenting with new onset abdominal pain and nausea?

Initial Bloodwork for Cirrhosis Patient with New Abdominal Pain and Nausea

In a patient with known cirrhosis presenting with new abdominal pain and nausea, you must immediately obtain a complete blood count, comprehensive metabolic panel (including liver function tests: bilirubin, albumin, ALT, AST, ALP, creatinine), INR/PT, and prepare for urgent diagnostic paracentesis with ascitic fluid analysis (cell count with differential, albumin, total protein, and bedside inoculation into blood culture bottles). 1, 2

Critical First-Line Laboratory Tests

Essential Serum Tests

• Complete blood count to assess for infection (leukocytosis), thrombocytopenia from hypersplenism, and anemia 3, 1
• Comprehensive metabolic panel including:
  • Bilirubin, albumin, ALT, AST, ALP, and GGT for liver synthetic function and disease severity 3
  • Creatinine to evaluate for hepatorenal syndrome or acute kidney injury 1, 2
  • Electrolytes to assess for hyponatremia and metabolic derangements 3
• INR/PT to assess synthetic liver function and coagulopathy severity 3, 1

Why These Tests Matter

The AST:ALT ratio helps assess fibrosis severity (ratio >1 indicates advanced fibrosis/cirrhosis), and these values can be normal even in established cirrhosis 3. Serum albumin is essential because you need it simultaneously with ascitic fluid albumin to calculate the serum-ascites albumin gradient (SAAG) 1, 2.

Urgent Diagnostic Paracentesis is Mandatory

You cannot skip paracentesis in this clinical scenario. New abdominal pain and nausea in a cirrhotic patient demands immediate exclusion of spontaneous bacterial peritonitis (SBP), which can be asymptomatic and is life-threatening 1, 2.

Required Ascitic Fluid Tests

• Cell count with differential - neutrophil count >250 cells/mm³ diagnoses SBP 1, 2
• Albumin - to calculate SAAG (serum albumin minus ascitic albumin) 1, 2
• Total protein - values <1.5 g/dL indicate high SBP risk 1, 2
• Bacterial culture - inoculate at least 10 mL into blood culture bottles at bedside (increases sensitivity from ~50% to >80-90%) 1, 2

SAAG Interpretation

SAAG ≥1.1 g/dL indicates portal hypertension with 97% accuracy, while SAAG <1.1 g/dL suggests non-portal hypertension causes 1, 2. This distinction is critical for determining the underlying cause of ascites.

Additional Tests Based on Clinical Suspicion

If Specific Complications Suspected

• Ascitic fluid glucose and LDH if secondary bacterial peritonitis suspected (glucose <50 mg/dL or ascitic LDH higher than serum LDH suggests bowel perforation) 2
• Ascitic fluid amylase if pancreatic disease suspected 2
• Ascitic fluid triglycerides if fluid appears milky (>200 mg/dL confirms chylous ascites) 4
• Ascitic fluid cytology if malignancy suspected (96.7% sensitivity with three samples) 2

Critical Timing and Safety Considerations

Do NOT Delay Paracentesis

Diagnostic paracentesis should be performed immediately upon presentation, even without overt signs of infection, as SBP can be completely asymptomatic 1, 2. The European Association for the Study of the Liver and American Association for the Study of Liver Diseases both mandate this approach 1, 2.

Coagulopathy is NOT a Contraindication

Do not delay paracentesis to correct INR or platelet count. Routine prophylactic correction of coagulopathy is not recommended 1. Severe hemorrhage occurs in only 0.2-2.2% of procedures with a death rate of 0.02% 1. Traditional coagulation tests (INR, platelet count) do not predict procedural bleeding risk in cirrhosis because these patients have "rebalanced hemostasis" 3.

Common Pitfalls to Avoid

• Never start antibiotics before obtaining cultures - this significantly reduces bacterial culture yield 1, 2
• Never skip paracentesis even if the patient appears stable - SBP is frequently asymptomatic 1
• Never rely solely on appearance of ascitic fluid - turbid fluid can result from infection or tumor cells, not just chylous ascites 4
• Never forget to obtain simultaneous serum albumin - you cannot calculate SAAG without it 1, 2

Algorithmic Approach

1. Immediately order: CBC, CMP (including liver panel), INR/PT 3, 1
2. Perform urgent diagnostic paracentesis with ascitic fluid: cell count with differential, albumin, total protein, bedside culture inoculation 1, 2
3. Calculate SAAG using simultaneous serum and ascitic albumin 1, 2
4. Assess neutrophil count: >250 cells/mm³ = start empiric antibiotics for SBP 1, 2
5. Add context-specific tests only if clinical suspicion warrants (amylase, cytology, triglycerides) 4, 2