Efficacy of transcerebellar to abdominal circumference versus head circumference to abdominal circumference ratio in predicting asymmetrical intrauterine growth restriction

Abstract

 Background: Fetal growth restriction (FGR) is when fetus is not able to achieve its genetic growth potential. The high incidence of FGR in general obstetric population and its low recognition, together lead to increased perinatal morbidity and mortality, and its early detection is useful in deciding frequency of antenatal surveillance and to optimize time of delivery to improve the neonatal outcome. TCD/AC ratio is a gestational age independent parameter, which may be helpful in early detection of FGR.

Objectives:

1. To compare the accuracy of transcerebellar to abdominal circumference with head circumference to abdominal circumference in predicting asymmetrical FGR after 20 weeks of gestation.
2. To determine the significance of TCD and TCD/AC relationship in predicting fetal outcome as expressed by perinatal morbidity and mortality.

Study design: A prospective observational study.

Methods: This was a prospective observational study conducted in the Postgraduate Department of Obstetrics and Gynaecology. A total of 100 patients in the group A (study group) and 200 patients in the group B (comparative group) in the age group of 18-35 years were taken. Subjects with singleton, non-anomalous pregnancy, reliable dates, favourable lie to visualize posterior fossa and gestation of 20 weeks or more, were taken from the said age group and followed for maternal and neonatal outcome.

Results: The difference in TCD/AC ratio between patients with FGR (14.8±SD) and without FGR (13.10±SD) is statistically significant with p value of <0.0001 with good sensitivity (93%), specificity (94%) and diagnostic accuracy (93.66%) in predicting asymmetrical FGR when compared to HC/AC ratio with sensitivity 83%, specificity 93% and diagnostic accuracy of 89.66%.

Conclusion: TCD/AC ratio is constant throughout pregnancy and is increased in FGR compared to normal pregnancy and can be used as screening test to diagnose FGR.

Keywords: Fetal growth restriction, transcerebellar to abdominal circumference ratio, head circumference to abdominal circumference ratio