Standardization of the Romanowsky staining procedure: an overview

Area of Science:

• Hematology
• Dye Chemistry
• Medical Imaging

Background:

• Commercially available Romanowsky blood stains exhibit variability in composition and performance due to inconsistent dye mixtures and metallic salt contamination.
• Inconsistent staining performance hinders reliable digital processing of blood cell images, impacting diagnostic accuracy in hematology.

Purpose of the Study:

• To address the need for standardized Romanowsky stains with constant composition for reproducible results in hematology.
• To explore the feasibility of preparing standardized stains using specific, high-purity dye components.

Main Methods:

• Investigated the composition of commercially available Romanowsky stains, noting variations in thiazein dyes, brominated fluorescein derivatives, and metallic salt content.
• Identified key dye components for standardization: eosin Y, azure B, and methylene blue, considering the recent availability of pure azure B.
• Discussed the logistical challenges associated with achieving stain standardization.

Main Results:

• Commercial Romanowsky stains are variable mixtures, impacting their performance.
• Standardized stains can be prepared using defined mixtures of eosin Y, azure B, and methylene blue.
• The availability of pure azure B is a recent development enabling standardization.

Conclusions:

• Standardized Romanowsky stains are achievable and essential for consistent hematological analysis.
• A controlled specimen preparation technique is vital for optimal performance of standardized stains.
• Standardization will significantly benefit hematologists and improve the validity of digital blood cell image analysis.