Randomised evaluation of a prototype suction fetal scalp electrode

To compare the performance and acceptability of a prototype suction fetal scalp electrode with that of a double helix spiral electrode.

An urban academic hospital in Johannesburg, South Africa.

Randomised, by means of sealed opaque envelopes opened consecutively.

One hundred women in active labour with an indication for direct fetal heart rate monitoring.

Application of a fetal scalp electrode to the presenting part.

Performance of the electrodes with respect to application success, detachment, quality of the tracings, scalp trauma and women's preferences.

Application of the suction electrode was unsuccessful in 15/50 (30%) compared to 1/50 (2%) with the spiral electrode. Detachment rates were similar. There were more tracings of average quality with the suction electrode (nine versus four). There were three instances of scalp bleeding at delivery with the spiral electrode. The suction electrode was preferred by more women and its application caused somewhat less discomfort.

The lower rate of successful application with the suction electrode needs to be weighed against the advantage of avoiding fetal scalp penetration. In particular, women's concerns about pain or harm to the baby from needle electrodes, the theoretical risk of viral transmission, and the risk of serious scalp infection must be considered. These factors favour the use of a suction electrode when direct fetal heart rate monitoring is required. Needle electrodes should be considered when suction electrode application is unsuccessful. Correction of practical problems experienced with the prototype suction electrodes used in this study may result in improved success rates.