Chinese Ink Staining in Ascitic Fluid
Chinese ink (India ink) staining is not a standard or recommended test for routine ascitic fluid analysis according to major hepatology guidelines, but it can be performed when cryptococcal infection is specifically suspected in immunocompromised patients.
Standard Ascitic Fluid Analysis
The established guidelines from EASL, AASLD, and KASL specify the following routine tests for ascitic fluid 1:
- Cell count and differential (neutrophil count to detect spontaneous bacterial peritonitis) 1
- Albumin concentration (to calculate serum-ascites albumin gradient) 1
- Total protein concentration (to assess SBP risk) 1
- Bacterial culture in blood culture bottles (inoculated at bedside) 1
Optional Tests Based on Clinical Suspicion
Additional tests should only be performed when specific diagnoses are suspected 1:
- Cytology - when malignancy is suspected 1
- Amylase - when pancreatic disease is suspected 1
- PCR and culture for mycobacteria - when tuberculosis is suspected 1
- Adenosine deaminase (ADA) - for tuberculous peritonitis (sensitivity 100%, specificity 96.6-100% when >32-40 U/L in non-cirrhotic patients) 1
Chinese Ink Staining Context
While not mentioned in the major cirrhosis and ascites guidelines reviewed, Chinese ink (India ink) staining is a traditional microbiological technique used to visualize encapsulated organisms, particularly Cryptococcus neoformans, which appears as budding yeast cells with clear halos against a dark background. This test would be relevant in:
- Immunocompromised patients (HIV/AIDS, transplant recipients, chronic corticosteroid use)
- When cryptococcal peritonitis is clinically suspected
- As part of fungal workup in unexplained ascites with lymphocytic predominance
Practical Recommendation
For routine ascitic fluid evaluation, Chinese ink staining should not be ordered 1. The standard workup focuses on detecting the most common and life-threatening conditions: spontaneous bacterial peritonitis, malignancy, and tuberculosis 1. If cryptococcal infection is suspected based on patient risk factors and clinical presentation, then cryptococcal antigen testing (more sensitive and specific than India ink) or fungal culture should be requested instead, as these have superior diagnostic performance compared to traditional ink staining.
The guidelines emphasize that other tests beyond the routine panel should only be ordered when there is specific clinical suspicion to avoid unnecessary costs and potential diagnostic confusion 1.