The Electronic Fetal Monitor In Perinatology

Abstract

The objective of electronic fetal monitoring is to permit timely and appropriate intervention when necessary during childbirth. Simply listening to the fetal heart does not give an accurate picture of fetal status. Small electrodes attached to the baby's scalp allow calculation of the instantaneous fetal heart rate. The entire nervous system including sympathetic and parasympathetic systems affect the fetal heart rate. It can be inferred that completely flat and unvarying heart rates of babies who have not received drugs such as demerol or atropine result from loss of oxygen to the baby's brain. The pattern of the rate of change, rather than the drop in heart rate, is a predictor of poor outcome. Other methods of monitoring fetal heart rate are used but are suboptimally effective in the ambulatory patient. Use of electronic fetal monitoring allows the reasons for ominous heart rate patterns to be understood, and any necessary adjustments to be made, as by repositioning the mother, which causes late deceleration to disappear in 90% of cases. In cases where electronic fetal monitoring reveals possible fetal distress, fetal blood may be sampled for acidity. Mothers who should appropriately undergo cesarean section can then be identified.