royal blue-top tube
roy·al blue-top tube(roy'ăl blū-top tūb)
A tube of this color indicates the container has either not been treated (plain) or has been treated with ethylenediaminetetraacetic acid as anticoagulant. These are used in the collection of whole blood or serum for trace element analysis.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012