Objective: To evaluate and compare interobserver variation in interpretation of intrapartum cardiotocograms.
Subjects: Fifteen senior (experience >4 years) and 16 junior (experience ≤4 years) obstetricians from 10 delivery units.
Design: Thirty-one obstetricians interpreted intrapartum cardiotocographic (CTG) readings from 22 parturients.
Methods: Inter-observer agreement in CTG interpretation and decision-making was assessed via proportions of agreement (Pa), with 95% confidence intervals (CI).
Main outcome measures: The level of inter-observer agreement was analyzed by calculating Pa values for CTG baseline, variability, early, variable and late decelerations, uterine tonus, power of contractions, hypertonus and clinical decision.
Results: In assessments of normal cases the Pa were acceptable or good (0.63–0.82) as regards all CTG interpretation elements except for the power of contractions (0.24), but in assessments of abnormal cases the Pa values were lower (0.18–0.60). As regards clinical decisions, a higher Pa was found in cases without recommendation for intervention (0.63, 95% CI 0.62–0.64) than in cases with such recommendation (0.55, 95% CI 0.54–0.56). The Pa in the abnormal cases was better among senior than among junior obstetricians.
Conclusions: Inter-observer variation in interpretation of abnormal CTG readings and recommendations for intervention is relatively wide. To improve reliability, uniform classification and standardized training in CTG interpretation are needed, as well as increased use of computerized CTG.