Intrapartum Heart Rate Ambiguity: A Comparison of Cardiotocogram and Abdominal Fetal Electrocardiogram with Maternal Electrocardiogram

Objective/Aims: To investigate the presence of signal ambiguity of intrapartum fetal heart rate (FHR) monitoring during delivery by comparing simultaneous cardiotocogram (CTG), abdominal fetal electrocardiogram (ECG) with continuous maternal ECG. Methods: A total of 144 simultaneous CTG (Corometrics (c) 250 series), abdominal fetal ECG (Monica AN24 (TM)) and maternal ECG (Monica AN24 (TM)) recordings were evaluated. Main Outcome Measures: When the FHR is within 5 bpm of the maternal heart rate (MHR) acquired from the ECG, it is classified as 'MHR/FHR ambiguity'. Statistical analyses were performed with Fisher's exact test and the Wilcoxon signed-rank test. Results: Comparison of abdominal fetal ECG against CTG demonstrates significantly less 'MHR/FHR ambiguity' in both the first stage (mean 0.70 vs. 1.22%, p < 0.001) and second stage of labour (mean 3.30 vs. 6.20%, p < 0.001). Conclusion: Intrapartum FHR monitoring in daily practice via the CTG modality provides significantly more 'MHR/FHR ambiguity' than abdominal fetal ECG, which also provides additional information on the MHR. Copyright (C) 2013 S. Karger AG, Basel