Transcerebellar diameter / abdominal circumference (TCD/AC) versus (HC/AC) head circumference / abdominal circumference --- USG prediction of fetal growth restriction? What do we observe in north Kerala, India

: Fetal growth restriction (FGR) refers to a condition in which a fetus is unable to achieve its genetically determined potential. A ratio of TCD /AC which is gestational age independent is very useful in predicting FGR. This prospective comparative study compared trans-cerebellar diameter / abdominal circumference versus head circumference / abdominal circumference in predicting fetal growth restriction. : A cross- sectional study done in 200 pregnant women attending Malabar Institute of Medical Sciences hospital during March 2018- May 2019. 40 pregnant women in third trimester with clinically suspected FGR over one year were the cases and 160 with normal growth pattern were the controls. Evaluation was done with 3.5 MHz frequency ultrasound. Fetal parameters such as BPD, HC, AC and FL were measured. Data were collected in Excel. Two morphometric ratios- TCD/AC and HC/AC will be calculated. Both TCD/ AC ratio and HC/AC of study group were compared with that of control group. The values above 2 standard deviations (SD) above mean were taken as FGR and was confirmed by postnatal newborn assessment by modified Ballard score. New born weight was compared with Fenton’s chart. If it was less than 10 percentile for the gestational age, it was diagnosed as a real case of FGR. Maximum number of cases (46.5%) belonged to the group 26-30 years. Around 23.5% in the group 31-35 years, 23% <= 25 years and 7% of the cases were >35 years. Clinical examination accounts for a sensitivity of 89.74%, Specificity of 96.9%, positive predictive value of 87.5% and negative predictive value of 97.5%. The sensitivity for TCD/ AC ratio is 94.87%. Specificity is 99.37%, positive predictive value is 97.36% and negative predictive value is 98.76%. TCD/AC and HC/AC were gestational age independent parameters and can be used in detecting IUGR with good diagnostic accuracy. However, TCD/AC ratio had a better diagnostic validity and accuracy compared to HC/AC ratio in predicting asymmetric FGR