Factors influencing the pH value of foetal scalp blood with special reference to caput succedaneum.

Foetal loss and neonatal death rate are still challenges to obstetricians. Several techniques have been developed to estimate the foetal well-being in utero-the pH determination of the foetal blood being one of these. The technique has been described by Saling' and Morris and Beard.'" Several reports showed the reliability of this technique in predicting the Apgar score of the foetus."" There are, however, cases where the foetus is observed to be acidotic shortly before delivery, but is nevertheless born in a vigorous condition. On the other hand, there are conditions where the foetus is only minimally acidotic, but is severely depressed at birth. Bowe et al. called these false normal, false abnormal values. They reported an incidence of 10,4% false normals, and 7,6% false abnormals. Hon et al. reported that 20,1 % of samples with a greater pH than 7,20 were associated with an Apgar score of 1 6 at one minute. With a foetal pH of 7,20 or less, 57,7°{, of samples were associated with an Apgar score of 7 10 at one minute. Beard et al.'6 found that when the pH was more than 7,25, 92% of babies had an Apgar score of 7 or more. When the pH was less than 7,16, 80% of babies had an Apgar score of 6 or less. Several factors may lead to these false normal and false abnormal values.