Specimen Collection, Preparation and Handling

Preparing the Vacuum Tube

This article is presented as a guide for trained venipuncture technicians, or phlebotomists, and is not intended to train individuals in venipuncture technique.

Assembling Supplies.

Assemble the following supplies: lab coat, gloves, labels, needle holder, tourniquet, appropriate tubes, gauze or cotton balls, alcohol sponge, and adhesive strip. (See Figure 1). The aseptic method of collecting and transporting a blood specimen works on the principle of a vacuum tube for drawing blood. A standard double-pointed needle or multisampling needle (both disposable) may be used for venipuncture. Ordinarily, a 21- or 22- gauge needle is used. A small bore, sharp needle causes minimum patient discomfort; 22- or 23- gauge is the smallest bore (or lumen) size recommended to avoid hemolysis. A needle length of 1 to 1? inches permits an angle of entry that will not pierce both vein walls and enter tissue.

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When more than one blood specimen is required, multisampling needles and vacuum tubes make blood collection simpler and more efficient. (See Figure 2). A tiny rubber sleeve automatically closes when the vacuum tube is removed from the holder, preventing leakage and loss of blood when the tubes are being changed.

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During venipuncture, do not have the patient clench and unclench the first repeatedly. This will cause hemoconcentration (a local increase in red blood cells). Also, never leave a tourniquet on the arm for more than 2 minutes without releasing it. This can cause discomfort to the patient and may also cause hemoconcentration.

Preparing the Puncture Site.

After securing the tourniquet and reaffirming your selection of the best vein, both by sight and palpation, proceed as follows.


Note: When drawing blood, please follow all approved venipuncture procedures recommended for use by recognized organizations and/or in accordance with state regulations involving phlebotomy practices.

Considerations for Single and Multisampling Collection.

If only a single collection tube is required, remove the entire assembly from the arm when the vacuum is exhausted. Place a piece of dry sterile gauze over the needle and withdraw the needle carefully.

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Note: When multiple specimens are drawn from a single venipuncture, the following order is recommended: 1) sterile blood culture tubes, 2) not additive clotting tubes (red), 3) coagulation tubes and tubes containing citrate (blue), 4) serum-separator tubes, 5) tubes containing heparin (green or royal blue), 6) tubes containing K3 EDTA (lavender), 7) tubes containing acid citrate dextrose (ACD yellow), and 8) tubes containing sodium fluoride and potassium oxalate (gray).

Note: If the blood has to be mixed with an anticoagulant, this must be done immediately after drawing. You can do this quickly while the patient’s arm is elevated. Mix blood with anticoagulant thoroughly, using a rolling wrist motion and by inverting the tube gently five or six times. (See Figure 9).

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FIG 9 FIG 10

Syringe Transfer Technique in Venipuncture

With the syringe technique, venipuncture is accomplished without direct connection to the collection tube. To ensure specimen integrity, follow these steps.

Note: When multiple specimens are prepared from syringe-filled tubes, the following order is recommended: 1) sterile blood culture tubes, 2) coagulation tubes and tubes containing sodium citrate (blue), 3) tubes containing K3 EDTA (lavender), 4) tubes containing heparin (green or royal blue), 5) tubes containing acid citrate dextrose (ACD yellow), 6) tubes containing sodium fluoride and potassium oxalate (gray), and 7) nonadditive clotting tubes (red or serum-separator).

Blood Preparation Procedures

There are two important guidelines to follow when submitting blood specimens. For some tests, such as chemistry procedures, fasting samples are often the specimen of choice. Also, because hemolysis and lipemia interfere with many procedures, please submit samples that are as free from hemolysis and lipemia as possible.

Preparing Serum

Serum Preparation From Red-Top Tube.

Follow the steps below when preparing a serum specimen for submission.

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FIG 11 FIG 12

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FIG 13 FIG 14

Serum-Separator Tubes.

Serum-separator (mottled red/gray or cherry red-top) tubes contain clot activator and gel for separating serum from cells but include no anticoagulant. Adhere to the following steps when using a serum-separator tube. Do not use serum-separator tubes to submit specimens for which tricyclic antidepressant levels, Direct Coombs’, Blood Group, and Blood Types are requested. There are other times when serum-separator tubes should not be used. Always consult the test description prior to collection.

Plasma Preparation.

When plasma is required, follow these steps.

FIG 15