Cardiotocography used in combination with automatic ST segment analysis of the electrocardiogram of a fetus for its status monitoring during labor and delivery

Objective. To investigate the efficiency of a combined analysis of a cardiotocogram and in ST segment changes in a fetal electrocardiogram during labor and delivery and to determine the sensitivity and specificity of the method in the diagnosis of fetal hypoxia. Subjects and methods. The course of pregnancy and labor was prospectively studied in 215 women at the V.I. Kulakov Research Center of Obstetrics, Gynecology, and Perinatology. The study encompassed physical and ultrasound examinations, cardiotocography (CFG), direct fetal electrocardiography (ECG) during labor and delivery, analysis of lactate levels and acid-base balance in the fetal umbilical cord artery postpartum. According to labor CTG readings, there were 3 groups: 1) a normal curve (n = 138); 2) a dubious curve (n = 42); 3) an abnormal curve (n = 35). CTG was classified in accordance with the FIGO criteria. The electrocardiogram was assessed with an automatic analyzer, by taking into consideration of ST segment changes. Results. Analysis of laboratory data showed that the main cluster of samples with normal pH in the neonatal umbilical artery corresponded to the lactate concentration of ≤5.2 μmol/l. When the lactate level was more than 5.2 μmol/l, the values of acid-base balance were indicative of neonatal acidosis. This level was defined as cut-off for verification of fetal hypoxia. In the normal, dubious, and abnormal CGT curve groups, the sensitivity and specificity of CTG and ECG in diagnosing fetal hypoxia were 66.7% and 98.5%, 100% and 97.5%, 88.9% and 88.4%, respectively. In the second period or labor, these of CTG (80 and 57.6%) were much lower than those of a combination of CTG and direct ECG (100 and 57.6%). In our observations, epidural analgesia and labor augmentation with oxytocin were not followed by ST segment changes on the ECG curve. Conclusion. The combination of cardiotocography and direct ECG of a fetus during labor and delivery can effectively and timely diagnose the fetal status throughout the delivery. The sensitivity and specificity of the technique are higher than those of CTG only. The combined method improves the possibilities of fetal monitoring in the second period of labor.

cardiotocography, direct electrocardiography, ST segment analysis, fetal hypoxia, labor and delivery, lactate