Continuous intrapartum monitoring of fetal scalp pH

Forty patients were monitored intrapartum with a continuous fetal scalp tissue pH electrode in the mean time of 2.39 hours. The monitoring records were considered "accurate" with good correlation to the intermittent fetal scalp capillary pH values in 76.9 per cent. The correlation coefficient was 0.74. The "accuracy" improved in the latter 23 cases to 87 per cent with a correlation coefficient of 0.82. This improvement was probably due to modification of the application technique, as well as to a new calibration method at 37 degrees. Continuous fetal scalp pH monitoring was clinically useful in 65 per cent, it was partially useful in 20 per cent, but of no value in 15 per cent of the patients studied. There were no apparent maternal complications with the use of this technique and 38 of the infants had no sequelae. Two infants had complications: one developed inflammation of the electrode site. This was treated with antibiotics. One electrode broke during the application and a fragment of the electrode tip remained in the fetal scalp. All the infants were grossly normal and there was a good correlation between the continuous pH readings and the immediate neonatal outcome.