Fetal Heart Rate Monitoring Using Maternal Abdominal Surface Electrodes in Third Trimester: Can We Obtain Additional Information Other than CTG Trace?

BACKGROUND: Cardiotocography (CTG) is the most widely used procedure despite its low specificity for fetal acidosis and poor perinatal outcome. Fetal electrocardiography (fECG) with transabdominal electrodes is a new, non-invasive and promising method with greater potential for detecting impairment of fetal circulation. This study is the first that attempts to assess the usefulness of fECG in comparison to CTG during antepartum period.

OBJECTIVES: To determine if a single fECG examination along with CTG tracing and Doppler flow measurement in the fetal vessels has any additional clinical value in normal and intrauterine growth restricted (IUGR) fetuses.

MATERIAL AND METHODS: The study included 93 pregnancies with IUGR, 37 pregnancies with IUGR and brain sparing effect, and 324 healthy pregnant women. The T/QRS ratio, cerebro-placental ratio (CRP), and CTG tracings were analyzed. One-way analysis of variance and Spearman's rank correlation coefficient were applied. The relationship between results of the T/QRS ratio and CTG examination among the study groups was analyzed.

RESULTS: The highest average mean value of the T/QRS ratio was recorded in the IUGR group with a normal CPR and a pathologic CTG (0.235 ± 0.014). The highest average maximum values were observed in the groups of IUGR pregnancies with a reduced CPR with normal (0.309 ± 0.100), suspicious (0.330 ± 0.102) and pathologic (0.319 ± 0.056) CTGs. Analysis of variance revealed differences between study groups regarding maximum values and the difference between maximum and minimal values of T/QRS. Correlations between groups were insignificant.

CONCLUSIONS: Higher values of T/QRS ratio in IUGR pregnancies with normal and reduced CPR than in control group regardless of the result of CTG examination may indicate minimal worsening of intrauterine fetal well-being in growth retarded fetuses. No relationship between fECG examination and CTG tracings suggests that a single fECG does not provide any additional clinically significant information determining the condition of the fetus; however, further studies are required.