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The accuracy of ultrasonic fetal cardiography
The present work investigated the accuracy of ultrasound cardiography (uFCG) in registering the fetal heart rate variability. Five patients in early labour were studied. Two cardiotocographs (HP 8030A) were simultaneously recording uFCG and direct fetal electrocardiography (dFECG). The information was stored in an analogue FM tape recorder for further data processing. The number of beats registered by the two methods were counted, and the time intervals between the beats were calculated. The short term variability (STV) and the long term variability (LTV) were investigated according to the definitions of DE HAAN [3]. To get an acceptable correlation coefficient in STV of 0.78, a difference as high as 5 beats per minute (bpm) between the two registrations had to be allowed. For LTV, a correlation coefficient of 0.70 was reached at a difference of 2 bpm. The results of the study show that the uFCG can hardly be used in interpretation of the STV. As the visual examination of the cardiotocograms reflects the LTV rather than the STV [7, 9], the uFCG can be used for interpretation of LTV provided that "jitter" is absent on the tracing.
The present work investigated the accuracy of ultrasound cardiography (uFCG) in registering the fetal heart rate variability. Five patients in early labour were studied. Two cardiotocographs (HP 8030A) were simultaneously recording uFCG and direct fetal electrocardiography (dFECG). The information was stored in an analogue FM tape recorder for further data processing. The number of beats registered by the two methods were counted, and the time intervals between the beats were calculated. The short term variability (STV) and the long term variability (LTV) were investigated according to the definitions of DE HAAN [3]. To get an acceptable correlation coefficient in STV of 0.78, a difference as high as 5 beats per minute (bpm) between the two registrations had to be allowed. For LTV, a correlation coefficient of 0.70 was reached at a difference of 2 bpm. The results of the study show that the uFCG can hardly be used in interpretation of the STV. As the visual examination of the cardiotocograms reflects the LTV rather than the STV [7, 9], the uFCG can be used for interpretation of LTV provided that "jitter" is absent on the tracing.