92 Section III ■ Blood Sampling

c. Using forefinger and thumb to encircle the extremity or use forefinger and middle finger as a tourniquet (Fig. 14.4A)

6. Remove occlusion device and replace to promote optimal vein distension.

7. Syringe collection: Check syringe function and attach

to needle. Penetrate skin first and position for entry of

vein (Fig. 14.4A,B).

a. Angle of entry 15 to 30 degrees

b. Bevel up preferred for optimal blood flow (less

chance of needle occlusion by vein wall)

c. Direction of entry against the direction of blood

flow

d. If possible, insert needle at area where vessel bifurcates to avoid “rolling” of veins.

8. Collect sample by gentle suction

a. To prevent occlusion by vein wall

b. To avoid hemolysis

9. Release tourniquet.

10. Remove needle and apply local pressure with dry gauze

for 1 to 3 minutes or until complete hemostasis.

Drip Technique

1. Cut the extension tubing of the 23-guage butterfly needle catheter at 1 to 2 cm length (Fig. 14.2).

2. Follow steps 1 to 6, as above.

3. Insert the needle in the vein as in step 7, but without a

syringe attached to the needle.

4. Collect the drops of blood directly into specimen container (Fig. 14.5).

5. Short sterile hypodermic needles (23 or 24 gauge) may

also be used to collect blood samples by the drip

method but are sometimes less successful because the

blood may pool at the hub of the needle and clot.

6. Drip method cannot be used for blood culture or coagulation studies (6).

Scalp Vein

1. Shave adequate area of frontal or parietal scalp.

2. Use scalp vein needle set or 23-gauge butterfly.

3. Occlude vein proximally with finger.

4. Feel for a pulse to avoid entering an artery.

5. Use a shallow angle (15 to 20 degrees).

6. See F, “General Venipuncture.”

Proximal Greater Saphenous Vein (7)

1. Use only in older infants or in term neonates without

evidence of coagulopathy.

2. Have assistant hold infant’s thighs abducted with knees

and hips slightly flexed.

3. Locate femoral triangle (Fig. 14.6A).

a. Proximal boundary: Inguinal ligament

b. Lateral boundary: Medial border of sartorius muscle

c. Medial boundary: Lateral border of adductor longus muscle

A B

Fig. 14.4. A: Venipuncture technique. Note position of fingers with forefinger occluding vein proximally. B: Needle penetrating skin a short distance from site of venipuncture.

Fig. 14.5. Drip technique of blood collection.