CSLB General Building (B) — All Questions

According to the standard order of draw, which specimen is collected first when a blood culture is ordered along with other tests?

• a.Blood culture (sterile) tubes/bottles✓
• b.Light blue (sodium citrate) tube
• c.Lavender (EDTA) tube
• d.Red (no additive) tube

Blood cultures are always drawn first to maintain sterility and prevent contamination that could cause false results. The standard order of draw then proceeds to light blue, then serum tubes, then green, lavender, and gray. Following the correct order prevents additive carryover between tubes.

In the CLSI order of draw, which tube is collected immediately after blood culture bottles?

• a.Lavender (EDTA) tube
• b.Light blue (sodium citrate) tube✓
• c.Gray (sodium fluoride) tube
• d.Green (heparin) tube

The light blue sodium citrate tube for coagulation studies is drawn immediately after blood cultures. Drawing it early minimizes contamination from other additives that could affect clotting results. The order then continues with serum tubes, green, lavender, and gray.

A lavender-top (purple) tube is required for a complete blood count (CBC). Which additive does it contain?

• a.Sodium fluoride
• b.Sodium citrate
• c.EDTA✓
• d.Sodium heparin

The lavender-top tube contains EDTA, an anticoagulant that binds calcium and preserves the shape of blood cells, making it ideal for hematology tests such as the CBC. It must be gently inverted several times after collection to mix the additive. Clots form if it is not mixed, invalidating the sample.

A green-top tube is used for many chemistry (plasma) tests. Which additive does it contain?

• a.EDTA
• b.Sodium citrate
• c.Silica clot activator
• d.Heparin✓

The green-top tube contains heparin (sodium, lithium, or ammonium), an anticoagulant that inhibits thrombin to prevent clotting for plasma chemistry tests. It is inverted several times to mix. Choosing the correct additive tube ensures the specimen is suitable for the ordered test.

A gray-top tube containing sodium fluoride is most appropriate for which test?

• a.Glucose or lactate levels✓
• b.Complete blood count
• c.Coagulation studies (PT/INR)
• d.Blood typing

The gray-top tube contains sodium fluoride, an antiglycolytic agent that preserves glucose by preventing cells from metabolizing it, making it ideal for glucose and lactate testing. Potassium oxalate is often included as an anticoagulant. It is drawn last in the standard order of draw.

A plain red-top tube (no additive or with clot activator only) is typically used to collect which specimen type?

• a.Whole blood with anticoagulant
• b.Serum, after the blood clots✓
• c.Plasma requiring immediate anticoagulation
• d.A sterile blood culture

A plain red-top tube has no anticoagulant, so the blood is allowed to clot and then centrifuged to yield serum. Serum is used for many chemistry, serology, and blood bank tests. Because it contains no additive, a plain red tube does not require inversion to mix, though clot-activator tubes are inverted.

At what angle should the needle be inserted during a routine venipuncture?

• a.45 to 60 degrees
• b.Straight down at 90 degrees
• c.15 to 30 degrees, bevel up✓
• d.Parallel to the skin at 5 degrees

The needle is inserted at a 15 to 30 degree angle with the bevel facing up during venipuncture. A shallow angle follows the path of the vein and reduces the risk of passing through it. Too steep an angle can puncture the back wall of the vein.

To avoid hemoconcentration and inaccurate results, a tourniquet should not remain in place longer than:

• a.5 minutes
• b.4 minutes
• c.3 minutes
• d.1 minute✓

A tourniquet should be left on for no longer than 1 minute to prevent hemoconcentration, which can falsely elevate certain results such as potassium and protein. If more time is needed to find a vein, the tourniquet is released and reapplied after two minutes. It is loosened as soon as blood flow is established.

Which vein is generally the preferred first choice for routine venipuncture in the antecubital area?

• a.Median cubital vein✓
• b.Basilic vein
• c.Cephalic vein of the wrist
• d.A vein on the underside of the wrist

The median cubital vein is usually the first choice for venipuncture because it is large, well-anchored, and located away from major nerves and arteries. The cephalic vein is a second choice, and the basilic vein is used with caution due to its proximity to the brachial artery and nerves. Veins on the underside of the wrist are avoided due to injury risk.

When performing a capillary (heel) puncture on an infant, which area of the heel should be used?

• a.The center of the heel
• b.The medial or lateral (side) plantar surface of the heel✓
• c.The back curve of the heel
• d.The arch of the foot

Infant heel sticks are performed on the medial or lateral plantar (bottom) surface of the heel to avoid the bone, which lies close to the surface at the center and back of the heel. Puncturing over the bone can cause injury or infection. The puncture depth is also limited to protect the calcaneus.

The order of draw for capillary (skin puncture) collection differs from venipuncture. Which specimen is generally collected first from a capillary stick?

• a.Serum tubes
• b.Chemistry tubes
• c.Blood gases, then EDTA (hematology) tubes, then other additive and serum tubes✓
• d.Coagulation tubes

In capillary collection, blood gases are collected first, followed by EDTA (hematology) tubes, then other additive tubes, and serum last. EDTA is collected early to ensure an adequate, well-mixed hematology sample before the drop begins to clot. This order differs from venous draws, where the light blue coagulation tube comes early.

Immediately after filling an additive tube, what must the technician do to properly handle the specimen?

• a.Shake it vigorously to speed mixing
• b.Place it on ice regardless of the test
• c.Centrifuge it immediately at the bedside
• d.Gently invert it the recommended number of times to mix the additive✓

Additive tubes must be gently inverted the recommended number of times immediately after collection to mix the blood with the additive and prevent clotting or clumping. Vigorous shaking can cause hemolysis, which ruins the sample. The number of inversions varies by tube type and manufacturer.

A technician receives a report that a specimen was hemolyzed. Which action during collection most likely caused the hemolysis?

• a.Vigorously shaking the tube after collection✓
• b.Gently inverting the tube five times
• c.Filling the tube completely
• d.Using an appropriately sized needle

Vigorous shaking of a tube ruptures red blood cells and causes hemolysis, which can falsely elevate results such as potassium. Other causes include using too small a needle, drawing too forcefully, or leaving the tourniquet on too long. Proper gentle mixing and technique prevent hemolysis.

A serum separator tube (SST), often gold or tiger-topped, contains which components?

• a.An anticoagulant to prevent clotting
• b.A clot activator and a gel separator✓
• c.Sodium fluoride to preserve glucose
• d.EDTA for hematology testing

An SST contains a clot activator to speed clotting and a thixotropic gel that forms a barrier between serum and cells after centrifugation. This yields a clean serum sample for many chemistry and serology tests. It is inverted five times after collection and allowed to clot before spinning.

A test requires a fasting specimen. A patient scheduled for a fasting glucose reports eating breakfast an hour ago. What should the technician do?

• a.Draw the specimen anyway without comment
• b.Tell the patient to fast for one more hour, then draw
• c.Notify the nurse or provider and document that the patient was not fasting before proceeding✓
• d.Cancel the test permanently

Fasting typically requires no food or caloric intake for 8 to 12 hours, and eating invalidates a fasting result. The technician should notify the nurse or provider and document the patient's non-fasting status so an informed decision can be made about rescheduling. Accurate reporting protects the reliability of the result.

When should specimen tubes be labeled during the blood collection process?

• a.Before the patient arrives
• b.The next day during charting
• c.Only if the specimen looks abnormal
• d.At the bedside immediately after collection, in the patient's presence✓

Tubes are labeled at the bedside immediately after collection while still with the patient, after verifying identity with two identifiers. Labeling on the spot prevents mislabeling and misidentification, a serious safety error. The label includes the patient's name, identifiers, date, time, and collector's initials.