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Platelet count assessment from peripheral blood smear (PBS)
Dale I Webb1, Lisa Parker, Kendal Webb
1Katmai Oncology Group, 3260 Providence Drive, Suite 352, Anchorage, Alaska 99508, USA.
Alaska Medicine
|July 8, 2005
Summary
Microscopic examination of peripheral blood smears provides a reliable estimate of platelet counts, comparable to automated methods. Averaging 10 high-power fields and multiplying by 15,000 offers a practical approach for platelet estimation.
Area of Science:
- Hematology
- Laboratory Medicine
- Diagnostic Cytology
Background:
- Automated blood cell counters are standard for platelet enumeration.
- Manual platelet counting via peripheral blood smear microscopy remains a valuable diagnostic tool.
- Accurate platelet counts are crucial for diagnosing and managing bleeding disorders.
Purpose of the Study:
- To compare manual platelet counts from peripheral blood smears with automated machine counts.
- To evaluate the accuracy and reliability of microscopic platelet estimation.
Main Methods:
- Peripheral blood smears from 35 patients (23 thrombocytopenic, 1 high count, 11 normal) were analyzed.
- Platelets were counted microscopically across 10 and 25 high-power fields.
- Counts were estimated by multiplying field averages by 15,000 or 20,000.
- Visual counts were compared with automated blood cell machine results.
Main Results:
- Fair concordance between manual and automated counts was observed in 27 out of 35 specimens.
- Microscopic overestimation occurred in 5 specimens; underestimation in 3.
- Using a 15,000 multiplier yielded slightly better results than 20,000.
- Averaging 10 high-power fields was as effective as using 25 fields.
- Both normal and abnormal platelet counts could be reliably assessed microscopically.
Conclusions:
- Microscopic platelet counting using 10 high-power fields and a 15,000 multiplier provides a platelet count reasonably close to automated machine results.
- Manual peripheral blood smear examination is a viable method for estimating platelet counts, especially in resource-limited settings or for verification.
