Umbilical cord blood gas analysis; a comparison of two simple methods of sample storage.

Umbilical cord vessel acid-base analysis is increasingly employed as an end-point in the study of ante-partum and intra-partum care. Delay in processing the sample can results in erroneous values as a result of gaseous diffusion and continuing metabolism. The effect of delay was investigated for samples stored in heparinized syringes at room temperature and simultaneously stored samples in double clamped cord segments. Small, but statistically significant changes were seen for pH, base deficit and PCO2 over 30 min. Storage in the syringe results in the most reliable values for pH and base deficit, whereas the cord segments showed no changes in PO2 and PCO2.