When germline testing calls for blood rather than saliva, the choice of vacutainer is not a formality. Tube additive and draw order quietly determine whether the sample your lab receives is the sample its assay was validated for — and getting either wrong can compromise a germline panel before extraction even begins.
Additive is the first decision. For germline DNA, EDTA tubes are the workhorse: the anticoagulant preserves cellular DNA and is what most germline assays expect. Serum tubes and heparin tubes are wrong for this purpose — heparin in particular inhibits downstream amplification — so the tube color on the tray is a quality control point, not a detail.
Draw order matters too. When multiple tubes are collected in one venipuncture, the order of draw prevents additive carryover between tubes that could contaminate the sample destined for the genetics lab. A correct order of draw is basic phlebotomy discipline with real consequences for assay performance.
For any program running blood-based germline panels, standardizing on the validated tube and a documented draw order removes a whole class of avoidable failures. Blood is one of three collection modalities a workflow has to manage, and our guide to genetic sample collection tools maps when each — saliva, swab, or vacutainer — is the right specimen for the test in front of you.