P. vivax is suspected in a patient who has been traveling for months in the tropics. Blood was collected in a lavender top tube; however, the slide was not prepared for examination until the next day because the specimen came in on the night shift. Once the slide was prepared and ex-amined, Schüffner dots were not visible. Which one of the following statements explains this discrepancy?
a. Schüffner dots are not characteristic of P. vivax infections.
b. The blood film was most likely incorrectly prepared.
c. The blood should have been collected in a red top tube.
d. The blood remained in the tube too long, yielding false-negative results.
D
Blood collected using ethylenediaminetetraacetic acid (EDTA) anticoagulant is preferred; how-ever, if the blood remains in the tube for any length of time before blood film preparation, then the Schüffner dots may not be visible after staining (e.g., P. vivax), and other morphologic changes in the parasites will be observed.
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