Blood collection from intravenous lines: is one drawing site better than others?

OBJECTIVE Establish whether hemolysis in samples collected from intravenous lines is influenced by catheterization site. METHODS Blood was collected from all patients (67 total) admitted to the emergency department the same morning, through a 20-gauge catheter placed in a vein of the upper limb directly into an evacuated blood tube. Serum was tested for hemolysis index by multi-wavelength photometric readings. RESULTS The frequency of hemolyzed specimens was 30% (20/67). Hemolysis rate in median cephalic and basilic veins (17%) was comparable to that of median anterobrachial vein but lower than cephalic vein (29%; P = 0.01), basilic vein (33%; P < 0.01), and metacarpal plexus veins (75%; P < 0.01). Compared with median basilic and cephalic veins, the relative risk of hemolysis was 1.4 from median anterobrachial vein, 1.6 from cephalic vein, 1.9 from basilic vein, and 4.3 from metacarpal plexus veins. CONCLUSION Drawing blood from catheters placed distally from median veins carries higher hemolysis risk.