Experience with continuous tissue pH electrode in the human fetus during labor.

In our experience the method was reliable in about 80% of the cases. The unsatisfactory reliability in the remaining 20% was partly due to the electrode instability. This problem was solved by using the new type of electrode. It proved suitable for getting stable tracings for longer periods in all the cases we examined. We are unable to give an answer to the other problem regarding the absence of correlation in some cases between the tissue and the blood pH values, got through blood samples taken according to the Saling technique. In these cases, however, the tracing can be used for the recording of pH variations regardless of its absolute values. From our experience the main clinical indication of the method has been found to be in the variable decelerations with normal values of the blood pH. Using this method the frequent repetition of separate blood samplings would be avoided.