A blood film for a normal RBC count shows an average of 10 platelets per oil immersion field. Which value best correlates with this estimate per microliter?

To estimate the platelet count per microliter based on the observation of 10 platelets per oil immersion field, one can apply the established relationship between the number of platelets seen in the field and the resulting count per microliter. In routine practice, it is common to assume that each oil immersion field contains a total volume that, when multiplied by the average count seen, can yield an approximate platelet count.

Typically, the formula utilized for converting the manual count from the microscopic field to a per microliter estimate involves multiplying the count per field by a factor that accounts for the dilution of blood and the volume of the oil immersion field observed. This factor is usually in the range of 20,000 to 40,000, depending on the specific microscope and slide used.

In this case, observing an average of 10 platelets per oil immersion field aligns with an estimated count of approximately 200,000 platelets per microliter. This estimation helps bridge the visual count in the field and the actual hematologic values that are critical for evaluating a patient’s platelet status. Hence, the value that best correlates with the estimate derived from observing 10 platelets per oil immersion field is around 200,000 per microl