Introduction
Electronic fetal monitoring
Internal (direct) electronic monitoring
FIGURE 24-1
Internal electronic fetal monitoring. Schematic representation of a bipolar electrode attached to the fetal scalp for detection of fetal QRS complexes (F). Also shown is the maternal heart and corresponding electrical complex (M) that is detected.
FIGURE 24-2
Schematic representation of fetal electrocardiographic signals used to compute continuing beat-to-beat heart rate with scalp electrodes. Time intervals (t 1 ,
t 2 , t 3 ) in milliseconds between successive fetal R waves are used by a cardiotachometer to compute instantaneous fetal heart rate.
FIGURE 24-3
The top tracing shows standard fetal monitor tracing of heart rate using a fetal scalp electrode. Spiking of the fetal rate in the monitor tracing is due to premature atrial contractions. The second panel displays accompanying contractions. The bottom two tracings represent cardiac electrical complexes detected from fetal scalp and maternal chest wall electrodes. ECG = electrocardiogram; F = fetus; M = mother; PAC = fetal premature atrial contraction.
FIGURE 24-4
Placental abruption. In the upper panel, the fetal scalp electrode first detected the heart rate of the dying fetus. Axer fetal death, the maternal electrocardiogram complex is detected and recorded. The second panel displays an absence of uterine contractions.
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