Manual thrombocyte enumeration on a stained blood film involves microscopic assessment to determine the number of platelets within a defined area. The resulting count, adjusted for factors such as the area observed and any dilution, provides an estimate of the platelet concentration in the patient’s blood. This method often utilizes a peripheral blood smear, commonly stained with Wright-Giemsa, where platelets are counted within a certain number of oil immersion fields. The average number of platelets per field is then used to calculate the overall platelet estimate.
This technique serves as a crucial adjunct to automated cell counters, particularly when flags or abnormalities are detected, or when instrument counts are unreliable due to platelet clumping or other interferences. Historically, it was the primary method for determining platelet levels and continues to offer a valuable check on automated results, ensuring accuracy in patient diagnosis and management. The method remains essential in resource-limited settings where sophisticated laboratory equipment may not be available.
