Accuracy of diagnosis of fetal distress as indication for a cesarean section

OBJECTIVE: The aim of our study was to determine the accuracy of interpretation of CTG as indication of fetal distress leading to the performing of caesarean sections (CS) and the influence of two variables: time of the day and experience of the doctors. STUDY DESIGN: Between Jan. and Dec. 2004, 123 CTG traces from full term patients that underwent a CS for fetal distress (14% of total) were interpreted following the RCOG Guideline for electronic fetal monitoring. In 2004 the number of CS in our Department were 870 out of 3187 deliveries (27.3%). On the basis of this re-reading we identified 3 groups: reassuring, not reassuring and abnormal. We estimated 2 variables: a) the time of the day: day and night; b) the experience of the doctor (perinatologysts or not). Statistical analysis (Chi square and Crame`r’s V) were performed to understand the effects of the doctor’s experience on the misinterpretation variable. RESULTS: The re-classification of the 123 tracings were the following: 16: reassuring; 42: not reassuring; 65: abnormal. If the CS had been performed only for abnormal patterns the incidence of CS for fetal distress would have dropped from 14% to 8%. When the CS was not appropriate, the decision had been made in 42 cases (72.4%) by a non perinatologist doctor (p! .01). When the CS was not appropriate, in 35 cases (60.3%) it had been performed during the night hours. Descriptive analysis shows that misinterpretations were more frequent during night hours, while correct interpretations were equally distributed between night and day hours. CONCLUSION: The accuracy of diagnosis of fetal distress on the basis of CTG can reduce the incidence of CS for fetal distress by half using a well defined classification and by adopting a conservative management of the not reassuring patterns. The incorrect diagnosis of fetal distress is more often given by ob/gyn doctors not involved in perinatology. Moreover night hours present a trend which reveals a potential role for the time of the day in the interpretation of the tracing.