Evaluation of continuous fetal scalp pH during labor.

Continuous monitoring of fetal scalp tissue pH was technically acceptable in 79.4% of 35 patients sequentially studied. Overall, the correlation coefficient (r) between the continuous pH readings and the intermittent pH values was 0.75. The accuracy improved greatly in the latter 23 patients. This was probably due to improved skills of the operators but also to a revision of the calibration technique. The correlation coefficient in these 23 patients was 0.82, and 87% of the records were accurate. The mean monitoring time was 2.39 h and eight infants were monitored throughout delivery and post natal. Although good results were obtained in this study, the method still demands technical skill in order to achieve clinically useful results.