Mastering Vacutainer Techniques in Phlebotomy Quiz

The correct order of draw—blood culture, light blue, red, SST, green, lavender, and gray—prevents cross-contamination between additives. Blood cultures are collected first to avoid contamination. The light blue tube comes next for coagulation tests, followed by serum tubes. SST ensures clotting separation, and anticoagulant tubes follow in sequence to prevent additive interference. Gray is last because it contains oxalate and fluoride, which could alter earlier samples if drawn sooner.

Cryofibrogen specimens require heat block transport because they must remain at body temperature (37°C) to prevent precipitation of cryoproteins. If the temperature drops, cryofibrinogen can solidify and affect test accuracy. A heat block ensures thermal stability during transport, preventing degradation or false readings. Urine, saliva, or plasma samples are typically stable at room temperature or under refrigeration, so they don’t require such temperature-controlled conditions.

Shock causes a drop in blood pressure due to decreased perfusion, rapid pulse, and clammy skin. However, increased blood pressure is the opposite of what occurs during shock. The condition leads to low perfusion, reduced tissue oxygenation, and compensatory mechanisms that increase heart rate but lower blood pressure. Understanding these hemodynamic changes helps healthcare workers identify shock early and initiate prompt resuscitative measures.

The interior or medial side of the heel is the safest site for infant heel puncture because it avoids the calcaneus bone and major blood vessels. The posterior curvature and center of the heel pose risks of nerve or bone injury. Puncturing the lateral or medial plantar surface ensures sufficient capillary flow while minimizing pain and complications such as osteomyelitis or necrosis.

A hematoma forms when blood leaks from a punctured vessel into surrounding tissues during venipuncture. The localized swelling results from trapped blood, sometimes clotted. It appears as a bruise and may cause mild pain or discoloration. Prompt removal of the needle, application of pressure, and proper post-venipuncture care reduce hematoma formation. Recognizing early signs like swelling ensures safety and patient comfort.

The light blue tube contains sodium citrate, which prevents clotting by binding calcium, making it ideal for coagulation tests like PT, aPTT, and D-dimer. The ratio of blood to additive (9:1) must be precise for accurate clotting analysis. Using other tubes would alter calcium balance and invalidate test results. Coagulation studies depend on controlled anticoagulant conditions that sodium citrate uniquely provides.

The median cubital vein, located in the antecubital fossa, is most commonly used for venipuncture because it is large, stable, and easily accessible. It offers a lower risk of complications compared to the basilic vein, which is near arteries and nerves. The cephalic vein is an alternative when the median cubital is unavailable. Selecting this vein ensures efficient blood draw and patient comfort.

Fasting blood sugar (FBS) tests require the patient to fast for 8–12 hours to ensure accurate glucose measurement without post-meal fluctuations. Eating can elevate glucose levels, skewing results. Other tests like CBC or PT/INR don’t depend on fasting status. Accurate fasting helps clinicians assess metabolic or diabetic control without dietary interference.

The correct needle insertion angle for venipuncture is between 15 and 30 degrees, allowing smooth entry into the vein without transfixing it. A steeper angle increases the risk of vein puncture or hematoma, while a shallower one may miss the vein. The angle ensures optimal vacuum pressure and minimal tissue trauma, improving sample quality and patient safety.

A tourniquet is applied 3–4 inches above the puncture site to temporarily restrict venous blood flow, causing veins to become more prominent and easier to locate. It does not stop arterial flow or sterilize the site. Proper use enhances vein visibility without causing hemoconcentration or hemolysis. Timing is crucial—leaving it on too long can affect test accuracy and patient comfort.

A bill becomes law through multiple readings, committee and report stages in both Houses, followed by Royal Assent. Each stage ensures scrutiny, debate, and refinement before the bill becomes an Act of Parliament.

Parliamentary sovereignty means Parliament is the supreme law-making body. It can make or repeal any law, and its acts cannot be invalidated by courts. However, EU and human rights laws place limited practical constraints.