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Heme Insights 4_August 2025_HORIBA
This issue features morphology case study, age & EDTA effect on full blood count samples
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Morphology Case Study
Patient Details
Female (age not given)
| FBC | |
|---|---|
| WBC 11.20 (10^3/mm3) | MCH 29.8 (pg) |
| RBC 2.72* (10^6/mm3) | MCHC 34.9 (g/dL) |
| HGB 8.1* (g/dL) | PLT 519* (10^3/mm3) |
| HCT 23.2* (%) | RET 568 (10^9/L) |
| MCV 55 (fL) | |
Smear comment
Sickle cell anemia.
Aniso-poikilocytosis (++). Sickle cells (++). Echinocytes (++). Hypochromic RBCs (++). Reticulocytosis (21%).
To note:
- The white blood cells seem +/- altered,
- Apoptosis is clearly visible, especially on some images of Polynuclear Neutrophils,
- And the presence of Echinocytes (++).
The whole is very evocative of "old" blood and could initially be mistaken as such. However, anemia and the sickle-shaped red blood cells indicate a requirement for hemoglobinopathy investigation.
Echinocyte- small projections on red cell membrane
Sickle red cells
Polynuclear Neutrophils-varied shapes and sizes of a cell's nucleus (the part of the cell that contains chromosomes). The nuclei of PMNs have two or three lobes with deep divisions.
Aged Sample Effects on a Blood Smear
The Effects of an Aged Blood Sample on Blood Smear Morphology
The quality and interpretability of a blood smear are highly dependent on the freshness of the sample. Aged blood samples—those that have been stored for prolonged periods, especially at room temperature—can introduce a range of artefactual changes that may complicate or compromise hematological interpretation.
1.Morphological Changes in Aged Samples
Over time, cellular components within a blood sample begin to degrade. This degradation is particularly evident in blood smears prepared from samples older than 6–8 hours post-collection. The following artefacts are commonly observed:
Red Blood Cells (RBCs):
- Increased central pallor, cell distortion, or crenation (echinocytosis).
- Presence of artefactual spherocytes, making it difficult to differentiate from true spherocytosis.
- Rouleaux formation may increase due to plasma protein changes or sample drying effects.
- White Blood Cells (WBCs):
- Nuclear degeneration, with pyknotic or smudged nuclei, particularly affecting lymphocytes.
- Cytoplasmic vacuolation or granule loss in granulocytes.
- "Basket cells" or "smudge cells" due to cell fragility, especially in lymphocytes.
- Platelets:
- Aggregation is more common in aged samples.
- Degranulation or loss of platelet definition may occur.
2. EDTA-Induced Artefacts
Ethylenediaminetetraacetic acid (EDTA) is the anticoagulant of choice for most hematological studies. While it is effective at preventing clotting by chelating calcium, EDTA can induce artefacts over time:
- EDTA-Induced Pseudothrombocytopenia: Platelets may clump in the presence of EDTA, leading to falsely low platelet counts and visible platelet clumps on the smear.
- Leukoagglutination: Rarely, EDTA can cause white cell clumping.
- Granular and cytoplasmic changes: Extended exposure to EDTA leads to cytoplasmic vacuolation and nuclear condensation, particularly in neutrophils.
- RBC Morphology: Prolonged EDTA exposure can cause crenation and distortion of erythrocytes, mimicking pathological forms. See images below:
Slides below showing age deterioration:
Red cells showing central area of pallor & Rouleaux formation
Crenated & distorted red cells, platelet aggregation
Conclusion
To ensure accurate morphological interpretation, blood smears should ideally be prepared within 2–4 hours of collection. Delays beyond this window, especially when samples are stored at room temperature, can significantly alter cellular morphology due to both natural degradation and EDTA-induced artefacts. Awareness of these changes is essential for laboratory professionals to distinguish between true pathology and pre-analytical artefacts.
