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Techniques and best practices in the laboratory

6 tips to optimize your staining in hematology

Hematology lab technicians face many challenges. The workload is intense, and laboratories often experience staff shortages. These difficulties can lead to mistakes. Remembering basic procedures helps maintain high-quality and consistent results.

Staining smears for hematology examination requires care, skill, and sound procedures.  The below guide provides practical advice on best practice techniques and simple ways to avoid common errors.

RAL Staining tips


1. Use fresh blood.

Fresh blood smears are preferred for several reasons:

  • Better morphology. They provide a more accurate representation of blood cells’ shape, size, and color. This is because the cells are not altered by prolonged exposure to fixatives or stains.
  • Reduced artefacts. They have fewer artifacts or distortions compared to older blood samples that have undergone significant changes due to the aging process.
  • Easier to work with. Working with fresh blood smears is easier and can be spread more evenly on the slide. This makes it easier to create a uniform layer of cells for examination under the microscope.

2. Dry the smear well before staining and prefix the blood smear if needed.

In hematology, it is important to dry the smear before staining to ensure that the cells adhere to the slide and are not washed away during the staining process. It will avoid water artefacts and sample loss and have correct staining without misinterpretation. Additionally, drying the smear and prefixing the blood smear helps to preserve the morphology (shape and structure) of the cells, which is important for accurate diagnosis. If the smear is not dried properly before staining, the cells may not stick to the slide or may become distorted, making it difficult to accurately identify and classify them.

3. Ensure your staining stations are clean. Rinsing well after each staining cycle.

Staining stations must be kept clean because any contamination or residual stains can interfere with the accuracy of the test results. It can lead to misidentification or misclassification of the cells, which can ultimately affect the diagnosis and treatment of the patient.

The rinsing step is also important to prevent staining artefacts, overstaining, and misinterpretation and remove dye residues.

4. Use accurate timing and standardized staining protocols.

It is necessary to standardize your staining protocols, including the duration and temperature of each staining step, to achieve consistent and reproducible results. Make sure to follow the manufacturer's instructions for each reagent used to ensure sufficient and correct staining of cellular structures, and to avoid misinterpretation.

5. Ensure correct storage conditions for your reagents. 

Reagents used for staining can be sensitive to temperature, light, moisture, and other environmental factors. If not stored properly, the reagents can deteriorate, become contaminated, or lose their efficacy over time. This can result in unreliable staining results, false positives, or negatives, and decreased staining quality.

6. Replace reagents regularly.

To obtain optimal staining and avoid degradation, the reagents must be replaced regularly based on the number of slides stained, racks processed, or in accordance with the staining system protocol.