Detection of Foetal Compromise Using Conventional Biophysical Profile and a Proposed Biophysical Profile with the Non-stress Test replaced with Ultrasonographic Fetal Heart Rate Count

Abstract

ABSTRACT

Background

When abnormalities of the fetal wellbeing are recognized promptly and dealt with, asphyxia and therefore perinatal morbidity & mortality can be reduced. The objective of fetal monitoring is the prediction and diagnosis of fetal compromise before fetal/newborn morbidity with particular reference to brain damage or death occurs. Fetal compromise when detected may warrant urgent intervention and delivery. 

Objective: This study compared the conventional fetal biophysical profile that has Non-Stress Test (NST) component with a proposed fetal biophysical profile that replaces the Non-Stress Test component with real-time counting of the fetal heart rate by ultrasonography in terms of fetal compromise detection.

Study design: This study was a prospective randomized comparative study.

Methodology: Two groups, each of 108 consenting pregnant women at gestational age of 32 weeks and above and with indications for fetal biophysical profile were recruited following a computer generated randomization pattern. Pregnant women in one group had the Manning’s fetal biophysical profile and the other group had a fetal biophysical profile in which the CTG component was replaced with real-time ultrasonographic fetal heart rate counting. 

The fetal heart rate (FHR) was counted with ultrasound scanning machine 5 times in 10 minutes with at least 1 minute in-between each count. FHR of 120-160 beats per minute (bpm) is normal. Values of difference (between the highest count and the lowest count) between 5-25 beats within normal limit was scored 2. Difference between the highest count and the lowest count that is less than 5 or greater than 25 beats or any abnormal count was scored 0. The immediate neonatal outcomes at delivery in both groups were compared. Immediate neonatal outcome were assessed with the APGA scores. Normal results of group 1 compared with normal results of group 2. Abnormal results of group 1 compared with abnormal results of group 2. 

Demographic data, primary and secondary outcomes of both groups were compared using t-test (for quantitative measures) and chi-square for significance. Statistical Package for Social Sciences (SPSS) version 29.0 was used for data analysis. 

Justification: Having the Non-stress test CTG component of fetal biophysical profile at all times has been a tall order in our environment due to unavailability of CTG machine at most of the places where fetal biophysical profiles are done. This has led to a lot of confusion often times because the fetal heart rate assessment component is usually completely missing coupled with the fact that it is generally known that the total score of FBP should be 10. There is therefore need to explore and utilise alternative heart rate assessment modalities.

Results: The majority of the participants did their fetal biophysical profile at 35-37 weeks gestation. The rate of admission to NICU was found to be 23% in this study which is similar to other research findings. There is no statistically significant difference between the rate of neonatal ICU admission in the 2 groups, p-value=0.508. Maternal medical condition was the commonest indication (63%) for fetal biophysical profile in this study. Majority of patients that did fetal biophysical profile (69%) returned optimal results. The odds ratio for the association between mother’s medical conditions and the neonatal outcome in terms of APGAR score and neonatal admission is more than 3 (3.077; p-0.053) in this study. Binary logistic regression analysis of factors affecting neonatal outcome revealed the odds ratio of the factors are as follows; FBP results (OR=2.394), mother’s vital signs (OR=2.511) and mothers medical condition (OR=3.077) meaning they have strong effects on neonatal outcome.

Conclusion: Since the neonatal outcomes of both groups are similar and in the face of inadequacy of facilities for CTG especially in low resource economies, the CTG component can therefore be comfortably replaced with real time fetal heart rate counting especially on occasions that CTG is not available or impossible. 

Ethical consideration: Ethical approval secured and no conflict of interest on the part of any of the authors.

Key words: Biophysical profile, ultrasound, cardiotocography, fetal heart rate, electronic fetal monitoring.

Correspondent Author: RS Omotayo, Consultant Obstetrician and Gynaecologist, University of Medical Sciences Teaching Hospital Complex/ Specialist Hospital, Akure, Ondo State.

Phone: 08149496557; 08032073484. Email: dromota

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