Specimen Collection Manual and Test Catalog

1 mL whole blood; minimum 0.4 mL.

Expel excess air from syringe. Mix well immediately after collection. Due to sample instability, this test may only be collected and analyzed at a performing laboratory site (see below).

Room temperature (preferred). Transport immediately. If delay in transport is anticipated, place specimen on an ice slurry.

Stable 30 minutes at room temperature, 1 hour on an ice slurry.

Stability limits exceeded (greater than 30 minutes at room temperature) or greater than 1 hour from time of collection when on ice slurry), specimens containing large clots or air bubbles.

pH, 7.30 - 7.40; pCO2, 32 - 44; pO2, 23 - 35; Base excess -6 to -2 mmmol/L.

Cord Blood pH, pCO2, pO2, base excess (calculated)

Cord blood, BGCV

Cord blood gases are sometimes drawn from the umbilicus during delivery to document oxygenation status of the newborn during delivery. Acidosis (pH less than 7.1 in an arterial cord blood gas) suggests blood flow / oxygenation from mother to newborn may have been occluded during delivery. 

The umbilical vein carries oxygenated blood from the placenta to the fetus. It, therefore, reflects placental functions / maternal status. 

Occasionally both arterial and venous cord blood specimens may be drawn to judge the difference in acidosis coming from fetal and maternal sources.