In the order of draw for skin puncture, which item is drawn last?

Study for the Hematology 1 Test. Utilize flashcards and multiple-choice questions with detailed explanations. Prepare effectively for success!

The key idea is why we sequence draws during a skin puncture to protect sample integrity and test accuracy. Serum requires blood to clot and then be separated from the clot; any anticoagulant or gel residue from prior draws, or contamination from tissue fluid at the puncture site, can alter the clotting process or the composition of the serum after separation. To minimize that risk, the serum sample is collected last.

In contrast, the tube used for blood gas analysis is highly time-sensitive and must be collected promptly in a heparinized (or otherwise appropriate) tube to preserve pH and gas values; EDTA microtubes are needed early to preserve cellular morphology for hematology testing; and slides (smears) are prepared from the blood promptly to maintain the integrity of cellular features for microscopic evaluation. By drawing these first, you reduce the chance that their results will be distorted by later samples.