COMPUTERIZED ANALYSIS OF FETAL HEART-RATE IN POSTTERM PREGNANCY

Objective: To verify the possibility that computerized interpretation of fetal heart rate in postdate pregnancy could increase the sensitivity of the other methods used in the identification of fetuses at risk for fetal distress in subsequent labor. Methods: Computerized cardiotocography by means of a '2CTG' system was utilized in a longitudinal study of 104 carefully selected, low-risk, postdate patients. Patients with gestational hypertension, intrauterine fetal growth retardation, severe oligohydramnios, increased umbilical resistance, and sporadic variable or late decelerations were excluded from the longitudinal trial to avoid the influence that preexisting factors could have on the evolution of fetal heart rate recordings. Computerized results were not available for clinical decision. A comparison on visual and computerized interpretation of the recordings was made retrospectively without any knowledge of the clinical outcome. Results: A significant increase in the level of the basal frequency and a reduction in the variability, using the Interval Index (P < 0.05), were found in the group subjected to acute fetal distress during labor. The comparative evaluation of the same tracings using visual and computerized readings showed an increased sensitivity of the computerized reading (75 vs 25) of the positive predictive value (43 vs 17) and of the Kappa Index (36 vs 7). Conclusions: Although cardiotocography still has a low sensitivity and a high specificity, the application of computerized interpretation together with the evaluation of the other biophysical variables can increase the identification of subjects in postdate pregnancy who will risk acute fetal distress during labor.