h. STEP 8: Bleeding should be completed fairly rapidly to prevent the triggering
of the clotting mechanism. Units requiring more than eight minutes to draw may not be
suitable for preparation of platelet concentrates or antihemophilic factor; however, if
adequate blood flow is assured and constant agitation maintained, rigid time limits are
i. STEP 9: Blood flow will stop after the proper amount has been collected
when using the balance or vacuum-assist methods. Otherwise, the bag must be
weighed (spring scales) and the flow stopped manually. One milliliter of blood equals
1.053 gm to 1.055 gm, so the final container should weigh 425 gm to 520 gm (405 to
495 ml) plus the weight of the container with its anticoagulant.
j. STEP 10: Seal the tubing 4 to 5 inches from the needle by making a tight
knot or using a metal clip.
k. STEP 11: Grasp tubing on the donor side of the seal and press to remove
blood for a distance of no more than an inch. Clamp with hemostat.
l. STEP 12: Cut tubing between seal and hemostat. To fill processing tubes for
laboratory tests, other than compatibility testing, remove stopper from tubes, release
hemostat, and allow blood to flow directly from vein (see figure 1-7). Re-identify tubes with
container after filling.
Figure 1-7. Filling tubes for laboratory tests.