Which tests are used to determine if ascitic fluid is hemorrhagic?

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Testing for Hemorrhagic Ascitic Fluid

Visual inspection of ascitic fluid is the primary method to identify hemorrhagic ascites; a red blood cell count >10,000 cells/mm³ confirms the diagnosis, though this threshold is not routinely required when gross blood is visible.

Initial Assessment

When hemorrhagic ascites is suspected, the diagnostic approach begins with visual inspection during paracentesis—bloody or pink-tinged fluid is immediately apparent and distinguishes hemorrhagic from other types of ascites. 1

Core Laboratory Tests for All Ascitic Fluid

Regardless of appearance, every diagnostic paracentesis should include: 2, 1, 3

  • Cell count with differential (including red blood cell count)
  • Ascitic fluid albumin and simultaneous serum albumin to calculate SAAG
  • Total protein concentration
  • Bedside inoculation of ≥10 mL into blood culture bottles (before any antibiotics)

Distinguishing True Hemorrhagic Ascites from Traumatic Tap

Red Blood Cell Count Threshold

  • RBC count >10,000 cells/mm³ indicates hemorrhagic ascites rather than traumatic tap 1
  • Traumatic taps typically show clearing of blood as fluid is withdrawn, whereas true hemorrhagic ascites remains uniformly bloody 1

Correcting the Neutrophil Count

When blood is present (traumatic or hemorrhagic), the ascitic fluid neutrophil count must be corrected to avoid falsely diagnosing spontaneous bacterial peritonitis: 1

  • Subtract 1 neutrophil for every 250 red blood cells present in the ascitic fluid
  • This correction prevents unnecessary antibiotic treatment when the elevated neutrophil count is simply due to blood contamination

Determining the Cause of Hemorrhagic Ascites

Once hemorrhagic ascites is confirmed, the SAAG remains the most accurate test to determine the underlying etiology: 2

High SAAG (≥1.1 g/dL) – Portal Hypertension Causes

  • Hepatocellular carcinoma (most common malignant cause in cirrhosis)
  • Traumatic paracentesis in a cirrhotic patient
  • Rarely, ruptured varices or hepatic vein thrombosis

Low SAAG (<1.1 g/dL) – Non-Portal Hypertension Causes

  • Peritoneal carcinomatosis (especially ovarian, pancreatic, or gastric cancer)
  • Tuberculous peritonitis (may be hemorrhagic in 5-10% of cases)
  • Traumatic injury to abdominal organs

Additional Targeted Tests

When Malignancy is Suspected (SAAG <1.1 g/dL)

  • Cytology: Send 50 mL of fresh fluid immediately to the laboratory; sensitivity is 82.8% on first sample, 96.7% with three samples 1, 4
  • Tumor markers: CEA >5 ng/mL or alkaline phosphatase >240 U/L suggests gut perforation; other markers (CA 19-9, EpCAM) may help identify peritoneal carcinomatosis 2, 4
  • Do NOT order CA-125—it is elevated in all types of ascites and has no diagnostic value 2, 1

When Tuberculous Peritonitis is Suspected

  • Adenosine deaminase (ADA): ≥32-40 U/L has 100% sensitivity in non-cirrhotic patients; use ≥27 U/L cutoff in cirrhosis 4, 3
  • Acid-fast bacilli smear has 0-86% sensitivity and should not be relied upon 4

When Pancreatic Ascites is Suspected

  • Ascitic amylase >1,000 U/L or >6× serum amylase confirms pancreatic origin 2, 3

Common Pitfalls

  • Do not withhold paracentesis due to coagulopathy: Even with INR up to 8.7 or platelets as low as 19×10³/µL, bleeding complications occur in only ~1% of procedures (mainly minor abdominal wall hematomas) 2, 1
  • Prophylactic fresh frozen plasma or platelet transfusion is not recommended before paracentesis 2, 1
  • The only absolute contraindications are clinically evident disseminated intravascular coagulation or active fibrinolysis, which occur in <1 per 1,000 procedures 2, 1
  • Always correct the neutrophil count when RBCs are present to avoid misdiagnosing SBP 1

Practical Algorithm

  1. Perform paracentesis and visually inspect the fluid
  2. If bloody: Order RBC count to confirm >10,000 cells/mm³ and correct neutrophil count (subtract 1 PMN per 250 RBCs) 1
  3. Calculate SAAG from albumin levels 2
  4. If SAAG ≥1.1 g/dL: Consider hepatocellular carcinoma (obtain imaging), traumatic tap, or vascular thrombosis 5, 6
  5. If SAAG <1.1 g/dL: Order cytology (three samples if possible) and consider ADA if tuberculosis is endemic or patient is immunocompromised 1, 4
  6. Initiate empirical antibiotics immediately if corrected neutrophil count ≥250 cells/mm³, regardless of fluid appearance 2, 1

References

1
Guideline

Diagnostic Paracentesis in New‑Onset Ascites – Evidence‑Based Recommendations

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

2
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

3
Guideline

Diagnostic Paracentesis Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

4
Guideline

Cytology Criteria for Diagnosing Peritonitis

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

5
Research

Differential diagnosis of ascites.

Seminars in liver disease, 1997

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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