Diagnostic Ability and Reproducibility of NICE 2017 Intrapartum Cardiotocography Interpretation Guidelines: A Prospective Observational Study

Assessment of accuracy, intra-observer and inter-observer and agreement for CTG interpretation utilizing NICE guidelines 2017.

This prospective observational study was completed at a tertiary-level hospital. 1650 CTG tracings were interpretations by 5 clinicians with various levels of clinical experience according to NICE 2017 CTG interpretation guidelines were analyzed. Inter-observer and intra-observer congruence was ascertained by employing Fleiss’ kappa and Cohen’s kappa using SPSS statistical software. Sensitivity, specificity, predictive values, likelihood ratios and overall accuracy of various CTG parameters for acidemia were computed.

Different CTG parameters had varied inter and intra-observer congruence which improved among clinicians with more than 5 years of experience. The best agreement was seen for baseline fetal heart (k_f = 0.678), and others like identification of variability pattern, type of decelerations and concerning features of variable decelerations had fair to only slight agreement. Again, various CTG parameters had very diverse predictive values for metabolic acidosis. Overall CTG category had a sensitivity, specificity and overall accuracy of 85.00%, 82.64% and 82.67%, respectively. As a single parameter variable deceleration with concerning characters surpassed all other CTG variables for the prediction of acidosis.

NICE 2017 guidelines for CTG interpretation were found to have fairly good predictive accuracy for acidemia. CTG had a high negative predictive value. A high level of non-correspondence in few CTG parameters as determining variability, identification of the deceleration type and concerning features probably point to the requirement for further objectivity while defining these parameters.