Compare the pre-analytical handling requirements for whole blood, plasma, and serum specimens.

• A. Whole blood requires no anticoagulants; plasma requires clotting before centrifugation; serum requires anticoagulants during collection.
• B. Whole blood requires anticoagulants for certain tests; plasma requires anticoagulants and centrifugation to separate plasma; serum requires clotting then centrifugation to obtain serum.
• C. All three specimens are handled identically and require centrifugation.
• D. Serum is obtained without clotting and does not require centrifugation.

Answer: (B)

The key idea is that how a blood specimen is prepared depends on whether it must stay unclotted or be allowed to clot in order to obtain the required component. For whole blood, anticoagulants are often used when tests require the cells or to prevent coagulation; this keeps the sample in a usable, non-clottable state for certain analyses. To obtain plasma, blood is drawn into tubes containing an anticoagulant, mixed, and then centrifuged to separate the liquid plasma from the cellular portion. For serum, blood is collected without anticoagulants, allowed to clot, and then centrifuged to remove the clot, yielding serum which lacks clotting factors. This matches the described handling: whole blood may need anticoagulants for specific tests; plasma requires anticoagulants and centrifugation to separate plasma; serum requires clotting followed by centrifugation to obtain serum. The other options misstate anticoagulant use, clotting, or centrifugation requirements.