Role of Cardiotocography in Predicting Intrapartum Asphyxia, taking Apgar Score and Physical Examination as Gold Standard

Abstract

Objectives: To determine the positive predictive value of cardiotocography in predicting intrapartum asphyxia, taking APGAR score and physical examination as the gold standard.

Methodology: 383 total pregnant women aged between 18 and 40 years at term were included in the study. To properly calculate positive predictive value (which requires both positive and negative test results), the study included women with both abnormal and normal CTG findings. Abnormal CTG findings were characterised by baseline variability (<5 bpm) lasting more than ninety minutes, baseline FHR exceeding 180 beats per minute or falling below 100 bpm, and significant variable decelerations or late decelerations, with a depth greater than 60 bpm and duration exceeding 60 seconds. Patients’ females with previous miscarriage (as per history and clinical record) or having cord around the neck or placenta previa as per obstetrical scan were excluded. The neonates delivered were examined by the consultant of the Paediatrics Department. The APGAR score and physical examination were done. All CTG recordings were interpreted by a single consultant gynaecologist by using the same machine. Cases of intrapartum asphyxia were identified based on CTG findings, APGAR scores, and relevant physical examination results.

Results: In this study, true positive cases were 123, and false positive cases were 69. The positive predictive value of cardiotocography in predicting intrapartum asphyxia, taking APGAR score and physical examination as the gold standard, was 64.02%. The chi-square test statistic was 53.91 (p < 0.001); the reported p-value of 0.202 in the original table appears to be a typographical error.

Conclusion: This study concluded that cardiotocography has a moderately useful positive predictive value for identifying intrapartum asphyxia. However, given the approximately 36% false-positive rate (69/192 abnormal CTG cases), the test misclassifies more than one-third of abnormal results, so clinical decisions should integrate additional parameters.

Keywords: Apgar score, Cardiotocography, Intrapartum asphyxia.